The rising customer expectations, intermingling fields and high performance needs can be satisfied with the system based design. An intelligent Systems Design strategy can offer a quicker route to an optimum design and helps to increase designers' productivity and analyzes efficiency by providing the ability to explore the entire design space. Cadence Intelligent System Strategy enables a system design revolution and reduces project schedules with optimized continuous integration.(read more)

One of the key goals for USB4 is to retain compatibility with the existing ecosystem of USB3.2, USB 2.0 and Thunderbolt  products, and the resulting connection scales to the best mutual capability of the devices being connected. USB4 is designed to work with older versions of USB and Thunderbolt . USB4 Fabric support high throughput interconnects of 10 Gbps (for Gen 2) and 20 Gbps (for Gen 3) and supports Thunderbolt 3-compatible rates of 10.3125 Gbps (for Gen 2) and 20.625 Gbps (for Gen 3). It becomes very important to verify the Thunderbolt  backward compatibility with the designs. Though the support of USB4 Interoperability with Thunderbolt  3 (TBT3) is optional in USB4 host or USB4 peripheral device and required USB4 Hub and USB4 Based Dock but it is very essential to work in the existing ecosystem. 

Few Main features of USB4 Interoperability with Thunderbolt  3 (TBT3) Systems

• Support for Bi-Directional Pins & Retimers: TBT3 Active Cables can contain two bidirectional Re-timers which have the capability to send AT Responses on its RX channel. Router connected directly to such Retimer needs to support A Router that is connected directly to a bidirectional Re-timer shall support reception of Transactions on both TX and RX channels. 

• Bounce Mechanism: This feature is used by Router to access the Register Space of a Cable Re-timer that can only be accessed by its Link Partner.
• Asymmetric Negotiation: The Router which connects with Cable Retimers needs to follow Asymmetric TxFFE in Phase 5 of Lane Initialization. 
• USB4 Link Transitions: In TBT3 mode, the configuration of two independent Single Lane Links can be used non-transient state or Single Lane Link just using the Lane1 Adapter.

Cadence has a mature USB4 Verification IP solution that can help in the verification of USB4 designs with TBT3. Cadence has taken an active part in the Cairo group that defined the USB4 specification and has created a comprehensive Verification IP that is being used by multiple members. If you plan to have a USB4-compatible design, you can reduce the risk of adopting new technology by using our proven and mature USB4 Verification IP. Please contact your Cadence local account team, for more details.

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Introduction

Multiphysics is an integral part of the concepts around digital twins. In this post, I want to discuss the mechanical aspects of multiphysics in system simulations, which are critical for 3D-IC, multi-die, and chiplet design.

The physical world in which we live is growing ever more electrified. Think of the transformation that the cell phone has brought into our lives, as has the present-day migration to electronic vehicles (EVs). These products are not only feats of electronic engineering but of mechanical as well, as the electronics find themselves in new and novel forms such as foldable phones and flying cars (eVOTLs). Here, engineering domains must co-exist and collaborate to bring about the best end products possible.

Start with the electronics—chips, chiplets, IC packaging, PCB, and modules. But now put these into a new form factor that can be dropped or submerged in water or accelerated along a highway. What about drop testing, aerodynamics, and aeroacoustics? These largely computational fluid dynamics (CFD) and/or mechanical multiphysics phenomena must also be accounted for. And then how does the drop testing impact the electrical performance? The world of electronics and its vast array of end products is pushing us beyond pure electrical engineering to be more broadly minded and develop not only heterogeneous products but heterogeneous engineering teams as well.

Cadence's Unique Expertise

It's at this crossroad of complexity and electronic proliferation that Cadence shines. Let's take, for example, the latest push for higher-performing high-bandwidth memory (HBM) devices and AI data center expansion. These technologies are growing from several layers to 12, and I can't emphasize enough the importance of teamwork and integrated solutions in tackling the challenges of advanced packaging technologies and how collaboration is shaping the future of semiconductor innovation and paving the way for cutting-edge developments in the industry.

These layered electronics are powered, and power creates heat. Heat needs to be understood, and thus, the thermal integrity issues uncovered along the way must be addressed. However, electronic thermal issues are just the first domino in a chain of interdependencies. What about the thermal stress and warpage that can be caused by the powering of these stacked devices? How does that then lend to mechanical stress and even material fatigue as the temperature cycles from high to low and back through the use of the electronic device? This is just one example in a long list of many...

Cadence Multiphysics Analysis Offerings

The confluence of electrical, mechanical, and CFD is exactly why Cadence expanded into multiphysics at a significant rate starting in 2019 with the announcement of the Clarity 3D Solver and Celsius Thermal Solver products for electromagnetic (EM) and thermal multiphysics system simulations. Recent acquisitions of Numeca, Pointwise, and Cascade (now branded within Cadence as the Fidelity CFD Platform) as well as Future Facilities (now the Cadence Reality Digital Twin product line) are all adding CFD expertise. The recent addition of Beta CAE brings mechanical multiphysics to the suite of solutions available from Cadence. The full breadth of these multiphysics system analyses, spanning EM, thermal, signal integrity/power integrity (SI/PI), CFD, and now mechanical, creates a platform for digital twinning across a wide array of applications. You can learn more by viewing Cadence's Reality Digital Twin platform launch on the keynote stage at NVIDIA's GTC in March, as well as this Designed with Cadence video: NV5, NVIDIA, and Cadence Collaboration Optimizes Data Centers.

Conclusion

Ever more sophisticated electronic designs are in demand to fulfill the needs of tomorrow's technologies, driving a convergence of electrical and mechanical aspects of multiphysics in system simulations. To successfully produce the exciting new products of the future, both domains must be able to collaborate effectively and efficiently. Cadence is fully committed to developing and providing our customers with the software products they need to enable this electrical/mechanical evolution. From EM, to thermal, to SI/PI, CFD, and mechanical, Cadence is enabling digital twinning across a wide array of applications that are forging pathways to the future.

For more information on Cadence's multiphysics system analysis offerings, visit our webpage and download our brochure.

Explore Impacts of Finite Interconnect Impedance on PDN Characterization

Over the past few decades, many details have been worked out in the power distribution network (PDN) in the frequency and time domains. We have simulation tools that can analyze the physical structure from DC to very high frequencies, including spatial variations of the behavior. We also have frequency- and time-domain test methods to measure the steady-state and transient behavior of the built-up systems.

All of these pieces in our current toolbox have their own assumptions, limitations, and artifacts, and they constantly raise the challenging question that designers need to answer: How to select the design process, simulation, measurement tools, and processes so that we get reasonable answers within a reasonable time frame with a reasonable budget.

Read this award-winning DesignCon 2024 paper titled “Impact of Finite Interconnect Impedance Including Spatial and Domain Comparison of PDN Characterization.” Led by Samtec’s Istvan Novak and written with a team of nine authors from Cadence, Amazon, and Samtec, the paper discusses a series of continually evolving challenges with PDN requirements for cutting-edge designs.

Read the full paper now: “Impact of Finite Interconnect Impedance Including Spatial and Domain Comparison of PDN Characterization.”

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Power network design and analysis of 3D-ICs is a major challenge due to the complex nature and large size of the power network. In addition, designers must deal with the complexity of routing power through the interposer, multiple dies, through-silicon vias (TSVs), and through-dielectric vias (TDVs).
Cadence’s Integrity 3D-IC Platform and Voltus IC Power Integrity Solution provide a fully integrated solution for early planning and analysis of 3D-IC power networks, 3D-IC chip-centric power integrity signoff, and hierarchical methods that significantly improve capacity and performance of power integrity (PI) signoff while maintaining a very high level of accuracy at signoff. This blog summarizes the typical design challenges faced by today’s 3D-IC designers, as discussed in our recent webinar, “Addressing 3D-IC Power Integrity Design Challenges.” Please click here to view the full webinar.

Major Trends in Advanced Chip Design

From chips to chiplets, stacked die, 3D-ICs, and more, three major trends are impacting advanced semiconductor packaging design. The first is heterogenous integration, which we define as a disaggregated approach to designing systems on chip (SoCs) from multiple chiplets. This approach is similar to system-in-package (SiP) design, except that instead of integrating multiple bare die – including 3D stacking – on a single substrate, multiple IPs are integrated in the form of chiplets on a single substrate.

The second major trend is around new silicon manufacturing techniques that leverage silicon vias (TSVs) and high-density fanout RDL. These advancements mean that silicon is becoming a more attractive material for packaging, especially when high bandwidth and form factor become key attributes in the end design. This brings new design and verification challenges to most packaging engineers who typically work with organic and ceramic substrate materials.

Finally, on the ecosystem side, all the large semiconductor foundries now offer their own versions of advanced packaging. This brings new ways of supporting design teams with technologies like reference flows and PDKs, concepts that have typically been lacking in the packaging community. Cadence has worked with many of the leading foundries and outsourced semiconductor assembly and test facilities (OSATs) to develop multi-chip(let) packaging reference flows and package assembly design kits. The downside is that, with the time restrictions designers are under today, there isn’t enough time to simulate the details of these flows and PDKs further.

For those who must make the best electro/thermal/physical decisions to achieve the best power/performance/area/cost (PPAC), factors can include accurate die size estimations, thermal feasibility, die-to-die interconnect planning, interposer planning (silicon/organic), front-to-front and front-to-back (F2F/F2B) planning, layer stack and electromigration/ IR drop (EMIR)/TSV planning, IO bandwidth feasibility, and system-level architecture selection.

3D-IC Power Network Design and Analysis

The key to success in 3D-IC design is early power integrity planning and analysis. Cadence’s Integrity 3D-IC platform is a high-capacity 3D-IC platform that enables 3D design planning, implementation, and system analysis in a single, unified cockpit. Cadence’s Voltus IC Power Integrity Solution is a comprehensive full chip electromigration, IR drop, and power analysis solution. With its fully distributed architecture and hierarchical analysis capabilities, Voltus provides very fast analysis and has the capacity to handle the largest designs in the industry. Typically, 3D-IC PDN design and analysis is performed in four phases, as shown in Figure 1.

Phase 1 - Perform early power delivery network (PDN) exploration with each fabric’s PDN cascaded in system PI with early circuit models.

Phase 2 – Plan 3D-IC PDNs in Cadence’s Integrity 3D-IC platform, including micro bumps, TSVs, and through dielectric vias (TDVs), power grid synthesis for dies, and early rail analysis and optimization.

Phase 3 – Perform full chip-centric signoff in Voltus with detailed die, interposer, and package models, including chip die models, while keeping some dies flat.

Phase 4 – Perform full system-level signoff with Cadence’s Sigrity SystemPI using detailed extracted package models from Sigrity XtractIM, board models from Sigrity PowerSI or Clarity 3D Solver, interposer models from XtractIM or Voltus, and chip power models from Voltus.

Figure 1. 3D-IC PDN design and analysis phases

3D-IC Chip-Centric Signoff

The integration of Integrity 3D-IC and Voltus enables chip-centric early analysis and signoff. Figure 2 and Figure 3 highlight the chip centric early PI optimization and signoff flows. In early analysis, the on-chip power networks are synthesized, and the micro bumps and TSVs can be placed and optimized. In the signoff stage, all the detailed design data is used for power analysis, and detailed models are extracted and used for package, interposer, and on-die power networks.

Figure 2. Early chip-centric PI analysis and optimization flow

Figure 3. Chip-centric 3D-IC PI signoff

Hierarchical 3D-IC PI Analysis

To improve the capacity and performance of 3D-IC PI analysis, Voltus enables hierarchical analysis using chiplet models. Chiplet models can be reduced chip models in spice format or more accurate xPGV models which are highly accurate proprietary models generated by Voltus. With xPGV models, the hierarchical PI analysis has almost the same accuracy as flat analysis but offers 10X or higher benefit in runtime and memory requirements.

Conclusion

This blog has highlighted the major design trends enabled by advanced 3D packaging and the design challenges arising from these advancements. The design of power delivery networks is one of these major challenges. We have discussed Cadence solutions to overcome this PI challenge. To learn more, view our recent webinar, "Addressing 3D-IC Power Integrity Design Challenges" and visit the Voltus web page.

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Melika Roshandell, Cadence product marketing director for the Celsius Thermal Solver, recently published an article in Designing Electronics discussing how the use of modern thermal analysis techniques can help engineers meet the challenges of today’s complex electronic designs, which require ever more functionality and performance to meet consumer demand.

Today’s modern electronic designs require ever more functionality and performance to meet consumer demand. These requirements make scaling traditional, flat, 2D-ICs very challenging. With the recent introduction of 3D-ICs into the electronic design industry, IC vendors need to optimize the performance and cost of their devices while also taking advantage of the ability to combine heterogeneous technologies and nodes into a single package. While this greatly advances IC technology, 3D-IC design brings about its own unique challenges and complexities, a major one of which is thermal management.

To overcome thermal management issues, a thermal solution that can handle the complexity of the entire design efficiently and without any simplification is necessary. However, because of the nature of 3D-ICs, the typical point tool approach that dissects the design space into subsections cannot adequately address this need. This approach also creates a longer turnaround time, which can impact critical decision-making to optimize design performance. A more effective solution is to utilize a solver that not only can import the entire package, PCB, and chiplets but also offers high performance to run the entire analysis in a timely manner.

Celsius Thermal Management Solutions

Cadence offers the Celsius Thermal Solver, a unique technology integrated with both IC and package design tools such as the Cadence Innovus Implementation System, Allegro PCB Designer, and Voltus IC Power Integrity Solution. The Celsius Thermal Solver is the first complete electrothermal co-simulation solution for the full hierarchy of electronic systems from ICs to physical enclosures. Based on a production-proven, massively parallel architecture, the Celsius Thermal Solver also provides end-to-end capabilities for both in-design and signoff methodologies and delivers up to 10X faster performance than legacy solutions without sacrificing accuracy.

By combining finite element analysis (FEA) for solid structures with computational fluid dynamics (CFD) for fluids (both liquid and gas, as well as airflow), designers can perform complete system analysis in a single tool. For PCB and IC packaging, engineering teams can combine electrical and thermal analysis and simulate the flow of both current and heat for a more accurate system-level thermal simulation than can be achieved using legacy tools. In addition, both static (steady-state) and dynamic (transient) electrical-thermal co-simulations can be performed based on the actual flow of electrical power in advanced 3D structures, providing visibility into real-world system behavior.

Designers are already co-simulating the Celsius Thermal Solver with Celsius EC Solver (formerly Future Facilities’ 6SigmaET electronics thermal simulation software), which provides state-of-the-art intelligence, automation, and accuracy. The combined workflow that ties Celsius FEA thermal analysis with Celsius EC Solver CFD results in even higher-accuracy models of electronics equipment, allowing engineers to test their designs through thermal simulations and mitigate thermal design risks.

Conclusion

As systems become more densely populated with heat-dissipating electronics, the operating temperatures of those devices impact reliability (device lifetime) and performance. Thermal analysis gives designers an understanding of device operating temperatures related to power dissipation, and that temperature information can be introduced into an electrothermal model to predict the impact on device performance. The robust capabilities in modern thermal management software enable new system analyses and design insights. This empowers electrical design teams to detect and mitigate thermal issues early in the design process—reducing electronic system development iterations and costs and shortening time to market.

To learn more about Cadence thermal analysis products, visit the Celsius Thermal Solver product page and download the Cadence Multiphysics Systems Analysis Product Portfolio.

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Cadence is super excited to announce SPB 23.1 release —Your freedom to design boldly!  

These tools help engineers build better PCBs faster with the new 3D engine and optimized interface.  

We have been hard at work to bring you this release and believe that it will help you take control of the PCB design process with the powerful new features in Allegro X APD like: 

• Packaging Support in 3DX Canvas 

• 3DX Wire DRCs 

• Aligning Components by Offset 

• Text Wizard Enhancements 

• Device File Reuse for Existing Components for Netlist and Logic Import 

Watch this space to know all about What’s New in SPB 23.1.  

Regards 

Team PCBTech 

Cadence Design System 

For individuals, small businesses, or teams, START YOUR FREE TRIAL. 

Does anyone know how to not include a pbar in a constraint manager analysis? I have some relative delay constraints applied on a group of differential nets. When I analyze the design these all show an error. If I delete the plating bar from the design they are all passing. The plating bar gets generated on the Substrate Geometry / Plating_Bar class. I understand that I could just delete the plating bar to verify the constraint but the issue is when I archive this design I would like it to be clean meaning it is in the final state for manufacturing AND passing all constraints according to design reviews.

Anyone have an idea? 

Thank you!

Does anyone know whether it is possible to have multiple contact points for a bond wire on a large die pad? Note: This is different from adding multiple wires which I will also be doing. I need to add multiple bond connections to the same large die pad for redundancy connections to each pad for each wire. I have a large die pad which I need to have 5 wires with each wire having 3 bond connections to the same die pad.

Starting SPB 23.1, in Allegro X PCB Editor and Allegro X Advanced Package Designer, you can align components by using offset mode. Earlier only spacing mode was available.

Follow these steps to Align Components using Offset Mode:

1. Set Application Mode to Placement Edit.
2. Drag the components that need to be aligned and right-click and choose Align Components.
3. Now, in the Options tab, you will notice Spacing Section with Equal Offset. You can equally and individually offset the components by using the +/- buttons for increment or decrement.

Starting SPB 23.1, Allegro Package Designer Plus (APD+) has been rebranded as Allegro X Advanced Package Designer (Allegro X APD).

The splash screen for Allegro X APD will appear as shown below, instead of showing APD+ 2023:

For the Windows Start menu in 23.1, it will display as Allegro X APD 2023 instead of APD+ 2023, as shown below

23.1 Start menu 

In the Product Choices window for 23.1, you will see Allegro X Advanced Package Designer in the place of Allegro Package Designer +, as shown below: 

23.1 product title

Have you heard that starting SPB 23.1, Allegro Package Designer Plus (APD+) will be renamed as Allegro X Advanced Package Designer (Allegro X APD)? 

Allegro X APD offers multiple new features and enhancements on topics like Via Structures, Wirebond, Etchback, Text Wizards, 3D Canvas, and more. 

This post presents the new 3DX Canvas introduced in SPB 23.1. This can be invoked from Allegro X APD (from the menu item View > 3DX Canvas). 

Some of the key benefits of the new canvas: 

• This canvas addresses the scale and complexity in large modern package designs. It provides highly efficient visual representation and implementation of packages. 
  
• The new architecture enables high-performance 3D incremental updates by utilizing GPU for fast rendering. 
  
  
• Real-time 3D incremental updates are supported, which means that the 3D view is in sync with all changes to the database. 
  
  
• The new canvas provides 3D visualization support for packaging objects such as wire bonds, ball, die bump/pillar geometries, die stacks, etch back, and plating bar. 
  
  
• This release also introduces the interactive measurement tool for a 3D view of packages. Once you open 3DX Canvas, press the Alt key and you can select the objects you want to measure. 
  
• 3DX Canvas provides new 3D DRC Bond Wire Clearances with Real 3D DRC Checks. True 3D DRC in Constraint Manager has been introduced. If you open Constraint Manager, there will be a new worksheet added. Following DRC checks are supported: 

  Wire to Wire 
  Wire to Finger 
  Wire to Shape 
  Wire to Cline 
  Wire to Component

Have you ever encountered ERROR(SPMHNI-67) while importing logic? If yes, you might already know that you had to export libraries of the design and make sure that paths (devpath, padpath, and psmpath) include the location of exported files.  

Starting in SPB23.1, if you go to File > Import > Logic/Netlist and click on the Other tab, you will see an option, Reuse device files for existing components. 

After selecting this option, ERROR(SPMHNI-67) will no longer be there in the log file, because the tool will automatically extract device files and seamlessly use them for newly imported data. In other words, SPB_23.1 lets you reuse the device / component definitions already in the design without first having to dump libraries manually. An excellent improvement, don’t you think?  

Starting from SPB23.1, a new option, Allow DRCs to surrounding metal, has been added in the Etch-Back form to allow DRCs to the surrounding objects. form to allow DRCs to the surrounding objects.

The Allow DRCs to surrounding metal option lets you see and adjust objects instead of the current behavior, which sacrifices the width of the mask for the trace.

• When this option is turned off, it maintains the EB mask to another object clearance.
• When this option is enabled, it keeps the EB mask to the EM trace edge clearance and shows a DRC if the EB mask to another object spacing is out of rule.

Starting SPB 23.1, a new pin property, WIREBOND_PROFILE_NAME is introduced. This property can be used to define a wirebond profile to a die pin. When adding a wirebond, the pin will use the profile defined in the WIREBOND_PROFILE_NAME property associated to the die pin.

Assign the WIREBOND_PROFILE_NAME property to the die pin using Edit > Properties and set the desired wirebond profile name in the Value field.

The following image displays the WIREBOND_PROFILE_NAME property assigned to the pin and wire profile of the Wire Bond for that pin.

Have you ever thought of a handy utility to specify all necessary transmission line parameters to decide upon the stackup?   

Starting SPB 23.1, a handy feature Transmission Line Calculator, is built into Allegro X Advanced Package Designer (Allegro X APD). This feature will require either an SiP Layout license or can be accessed through SiP Layout Bundle. 

From the Analyze dropdown menu in the 23.1 Allegro X APD toolbar, you can choose Transmission Line Calculator. 

You can use this calculator to help decide constraints and stackup for laminate-based PCB or Packages. You can calculate the correct stackup material and width/spacing to meet any requirements that may be later entered in a constraint. This is truly a calculated number and not a true field solver. 

The different types of calculations that the Transmission Line Calculator can provide are Microstrip, Embedded microstrip, Stripline, CPW (Coplanar), FGCPW (frequency-dependent Coplanar), Asymmetric stripline, Coupled microstrip (Differential Pair), Coupled stripline (Differential Pair), and Dual striplines. 

This feature is important for customers relying on fabricators/spreadsheets to provide this information or need to test a quick spacing/width as per the impedance value. 

Let us know your comments on this new feature in 23.1 Allegro X APD. 

Starting SPB 23.1, Allegro X APD lets you import/export the symbol and component properties by using Die Text-In/Out wizards. 

Exporting the symbol 

You can export the symbol by using File > Export > Die Text-Out Wizard. 

In the Die Text-Out Wizard window, you can see the newly added options, that is, Component Properties and Symbol Properties. 

This entire information including the properties will be saved in a text file. 

Importing the symbol 

You can import the same text file in Allegro X APD by using Die Text-In Wizard. 

Choose the text file you want to import. 

Symbol properties added in the text file will be visible in the Die Text-In Wizard window. 

Hi，

I want to delete via use skill，but i dont write this skill. can you help me.

This skill has Interactive interface，the interface can imput  Select Net and select padstack；

I can  use temp group to select the via；

example，i want to delete via，the padstack is L1:L3，the net is vss. i can imput padstack  L1:L3 and select net: VSS；

Note: The green is VSS，the padstack L1:L3 and L3:L5 ；

thanks

At times, there might arise a condition in the design where you need to push the net of selected pins to all its physically connected objects. For example, a few pins are updated with a new net, and it is required to push the new net to all its connected objects. At times, you might update the die or copy routing to other components, when a portion of routing gets the wrong net.

To propagate the net of the pin to all its physically connected objects, Allegro X APD uses the standalone command, Push Connectivity.

You can call the command through Logic > Push Connectivity.

Alternately, you can use the push connectivity command at the command line. Once the command is active, it lets you select pins or symbols that will be used to push net connectivity to all connected objects.

Presently, dynamic shapes and filled rectangles are not considered as part of connectivity. Static shapes are supported.

hello, help me!

There are many change in the bump design. I want to design bump by APD.

The bump(die) is a stagger , create it by die generator. 

Because，the pin is not isometric. In order to RDL routing, so the bump is not isometric.

I move the symbol pin in APD symbol edit（as show in the picture）,  and selected symbol RBM write device file, write library symbol.

Export the bga text( bga text out) ,But the bump is not modified, the bump is still stagger.

Can you help me!

pitch2> pitch1

thanks

The vision manager is good tool for routing check. but no quickly or effective  tool to fix or optimize this  problems to be optimized.

For example, parallel Gap less than preferred, min seg/Arc length,uncoupled diff-pair segs，and so on.

I only know use spread between voids to fix the non-optimized segs. in fact it is inefficient.

the parallel gap less than preferred is only to slice evry trace, its inefficient.

If i set the paraller gap less than 50um, Is there any tool to quickly fix these problems（gap less than 50um）?

For other problems，i can use tool to quickly fix the min seg/Arc length，uncoupled diff pair segs，accoding to select by polygon or select  by windows.

Hi，

There are mang components in BGA ball side of flipchip package.

Are there DFA check space of compont body or pin soldermask to BGA ball or BGA PAD or bga  soldermask in allegro APD?

I only find space of compont to compont in APD DFA. 

In a package design, designers often need to perform degassing. This is typically done at the end of the design process before sending the design to the manufacturer.

Degassing is a process where you perforate power planes, voltage planes, and filled shapes in your design. Degassing holes let the gas escape from beneath the metal during manufacturing of the substrate. The perforations or holes for degassing are generally small, having a specified size and shape, and are spaced regularly across the surface of the plane. If the degassing process is not done, it may result in the formation of gas bubbles under the metal, which may cause the surface of the metal to become uneven. After you degas the design, it is recommended to perform electrical verification.

Allegro X APD has degassing features that allow users to automate the process and place holes in the entire shape.

In today’s topic, we will talk about how to avoid adding  degassing holes on a particular shape.

Sometimes, a designer may need to avoid adding degassing holes to a particular shape on a layer. All other shapes on the layer can have degassing holes but not this shape. Using the Layer Based Degassing Parameters option, the designer can set the degassing parameters for all shapes on the layer. Now, the designer would like to defer adding degassing holes for this particular shape.

You may wonder if there is an easy way to achieve this. We will now see how this can be done with the tool.

Once the degassing parameters are set, performing Display > Element on any of the shapes on that layer will show the degassing parameters set.

You can apply the Degas_Not_Allowed property to a shape to specify that degassing should not be performed on this shape, even if the degassing requirements are met. Select the shape and add the property as shown below.

Switch to Shape Edit application mode (Setup > Application mode > Shape Edit) and window-select all shapes on the layer. Then, right-click and select Deferred Degassing > All Off.

Now, all shapes on the layer will have degassing holes except for the shape which has the Degas_Not_Allowed property attached to it.

By default, a dielectric must separate each pair of conductor layers in the cross-section of a design. In rare cases, this does not represent the real, manufactured substrate.

If your design requires you to have conductor layers that are not separated by a dielectric (such as, for half-etch designs), there is a variable that needs to be set in Allegro X APD. You must set this by enabling the variable icp_allow_adjacent_conductors. This entry, and its location in the User Preferences Editor, are shown in the following image.

The Objects on adjacent conductor layers do not electrically connect together, automatically. A via must be used to establish the inter-layer connections.

When enabling this option, it is recommended to exercise caution because excluding dielectric layers from your cross-section can lead to inaccurate calculations, including the calculations for signal integrity and via heights. It is important that your cross-section accurately reflect the finished product to ensure the most accurate results possible. Any dielectric layers present in the manufactured part need to be in the cross-section for accurate extraction, 3D viewing, and so on.

Let us know your comments on the various designs that would require adjacent conductor layers.

Hi，

Can you tell me which setting is causing this?

In the general edit. I try slide via to other position. but the slide is wrong.

in the cm，i set pad-pad connect is all allowed，and i turn off via to pad spacing in the same net spacing. only turn on via to via spacing in the same net spacing，set to via to via spacing =0.

default the via is closer to the pad edge, I think the correct location is show in the pic2.

Power and Ground rings are exposed rings of metal surrounding a die that supply power/ground to the die and create a low-impedance path for the current flow. These rings ensure stable power distribution and reduce noise. Allegro X Package Designer Plus has a utility called Power/Ground Ring Generator which lets you define and place one or more shapes in the form of a ring around a die.

 To run the PWR/GND Generator Wizard, go to Route > Power/Ground Ring Generator or type "pring wizard" in the APD command window to invoke the Wizard.

This Wizard lets you define and place one or more shapes in the form of a ring around a die. The Power/Ground Ring Wizard creates up to 12 rings (shapes) at a time. If you require more rings, you can run the Power/Ground Ring Wizard as many times as needed. This command displays a wizard in which you can specify:

• The number of rings to be generated
• The creation of the first ring as a die flag (Die flag is the boundary of the die like the power ring.)
  • If you create a die flag and the first ring is the same net as the flag, you can enter a negative distance to overlap the ring and the die flag.
• Multiple options for placement of the rings with respect to:
  • Origination point
  • Distance from the edge of the die
  • Distance from the nearest die pin on each die side
• The reference designator of the die with which the rings will be used
• The distance between rings
• The width of each ring
• The corner types on each ring (arc, chamfer, and right-angle)
• An assigned net name for each ring
• A label for each ring

The rings are basic in nature. For other shape geometries or split rings, choose Shape > Polygon or Shape > Compose/Decompose Shape from the menu in the design window.

Depending on the options selected, the Power/Ground Ring Wizard UI changes, representing how the rings will be created. Verify the Wizard settings to ensure that the rings are created as intended.

1. When the Power/Ground Ring Wizard appears, set the number of rings to 2, accept the other defaults, and click Next. You can set Create first ring as die flag to create a basic die flag.

         2. Define Ring 1 and the net associated with it.

              a) Browse and choose Vss in the Net Names dialog box.

            b) Click OK.

            c) Specify the label as VSS.

            d) Click Next.

             The first ring should appear in your design. It is associated with the proper net; in this case, VSS.

2. For the second ring, choose the net as Vdd and specify the label as VDD.
3. Click Next.
4. Click Finish in the Result Verification screen to complete the process.

The completed rings appear as shown below.

Now, when you click on Power and Ground Die Pin and add wirebonds, you will see that the wirebonds are placed directly on the Power and Ground rings.

When working on a complex design, it is common to have very many net ratlines. Quantities like 1000 ratlines are possible. It can result in a cluttered view while routing. Therefore, it is useful to make all other ratlines invisible while routing interactively. You would like to make all ratlines visible again when each route action is completed.

You can easily do this by enabling the Auto-blank other rats option during routing. When enabled, all rats other than the primary ones are suppressed during the Add Connect command.

Hello, SKILL experts. 

I'm studying SKILL language to build some useful function in APD+.

Now, I want to execute 'Import Sub-drawing' function in new form.

But I cannot find how to do execute APD+ embedded function in a field of new form. 

Has anyone experienced this or idea to solve this problem? 

When things go wrong with your package design flow, it can sometimes be difficult to understand the cause of the issue. This can be something like a die component is wrongly identified as a BGA, a via stack has an alignment issue, or there are duplicate bondwires. These are just a few examples of issues; there can be many more. When interactive messages and log files do not help determine the problem, the Package Design Integrity Check tool becomes very handy. This feature lets you run integrity checks, which ensures that the database is configured correctly. 

To invoke the command from Allegro X Advanced Package Designer, use the Tools > Package Design Integrity menu. 

Or type package integrity at the Command  prompt. 

The Package Design Integrity Checks dialog box includes all categories and checks currently registered for the currently running product. You can enable all these categories and checks or only the one that you want to run. This utility can fix errors automatically (where possible). Errors and warnings are written to the “package_design_check.log” file.  

The utility can also be extended with your own custom rules based on your specific flows and needs. 

The DBDoctor application checks the database for errors and other problems, and presents a report about them. DBDoctor supports .brd, .mcm, .mdd, .psm, .dra, .pad, .sav, and .scf databases.

DBDoctor can:

• Analyze and fix database problems.
• Eliminate duplicate vias.
• Perform batch design rule checking (DRC).
• Upgrade databases more than one revision old.

To verify the integrity of a drawing database at any time during the design cycle, run DBDoctor at regular intervals but make sure you always run it after completing a design.

You can run DBDoctor to verify work in progress, or from a terminal window outside the layout editor, perhaps to check multiple input designs in batch mode by using wildcards and various switches. You do not have to run the layout editor to use DBDoctor.

To run this from Allegro X APD and Allegro PCB Editor, go to Tools > Database Check.

You can also go to the Start menu and select Cadence PCB Utilities 2023 > PCB DB Doctor 2023.

You can also use the following command to run DBDoctor in batch mode in the system command prompt:

dbdoctor [-check_only] [-drc] [-drc_only] [-shapes][-no_backup] [-outfile <newboardname.brd>]>

Comment below if you want to know more about this command and its integration with SKILL programming!!

Display Stream Compression (DSC) is a lossless or near-lossless image compression standard developed by the Video Electronics Standards Association (VESA) for reducing the bandwidth required to transmit high-resolution video and images. DSC compresses video streams in real-time, allowing for higher resolutions, refresh rates, and color depths while minimizing the data load on transmission interfaces such as DisplayPort, HDMI, and embedded display interfaces.

Why Is DSC Needed?

In the ever-evolving landscape of display technology, the pursuit of higher resolutions and better visual quality is relentless. As display capabilities advance, so do the challenges of managing the immense amounts of data required to drive these high-performance screens. This is where DSC steps in. DSC is designed to address the challenges of transmitting ultra-high-definition content without sacrificing quality or performance. As displays grow in resolution and capability, the amount of data they need to transmit increases exponentially. DSC addresses these issues by compressing video streams in real-time, significantly reducing the bandwidth needed while preserving image quality.
 

DSC Use in End-to-end System

DSC Key Features

• Encoding tools:
  • Modified Median-Adaptive Prediction (MMAP)
  • Block Prediction (BP)
  • Midpoint Prediction (MPP)
  • Indexed color history (ICH)
  • Entropy coding using delta size unit-variable length coding (DSU-VLC)

• The DSC bitstream and decoding process are designed to facilitate the decoding of 3 pixels/clock in practical hardware decoder implementations. Hardware encoder implementations are possible at 1 pixel/clock.
• DSC uses an intra-frame, line-based coding algorithm, which results in very low latency for encoding and decoding.

DSC encoding algorithm
 

• Compression can be done to a fractional bpp. The compressed bits per pixel ranges from 6 to 63.9375.
• For validation/compliance certification of DSC compression and decompression engines, cyclic redundancy checks (CRCs) are used to verify the correctness of the bitstream and the reconstructed image.
• DSC supports more color bit depths, including 8, 10, 12, 14, and 16 bpc.
• DSC supports RGB and YCbCr input format, supporting 4:4:4, 4:2:2, and 4:2:0 sampling.
• Maximum decompressor-supported bits/pixel values are as listed in the Maximum Allowed Bit Rate column in the table below

• DP DSC Source device shall program the bit rate within the range of Minimum Allowed Bit Rate column in the table:

Summary

Display Stream Compression (DSC) is a technology used in DisplayPort to enable higher resolutions and refresh rates while maintaining high image quality. It works by compressing the video data transmitted from the source to the display, effectively reducing the bandwidth required. DSC uses a visually lossless algorithm, meaning that the compression is designed to be imperceptible to the human eye, preserving the fidelity of the image. This technology allows for smoother, more detailed visuals at higher resolutions, such as 4K or 8K, without requiring a significant increase in data bandwidth.

More Information

• Cadence has a very mature Verification IP solution. Verification over many different configurations can be used with DisplayPort 2.1 and DisplayPort 1.4 designs, so you can choose the best version for your specific needs.
• The DisplayPort VIP provides a full-stack solution for Sink and Source devices with a comprehensive coverage model, protocol checkers, and an extensive test suite.
• More details are available on the DisplayPort Verification IP product page, Simulation VIP pages.
• If you have any queries, feel free to contact us at talk_to_vip_expert@cadence.com

Verisium SimAI App harnesses the power of machine learning technology with the Cadence Xcelium Logic Simulator - the ultimate breakthrough in accelerating verification closure. It builds models from regressions run in the Xcelium simulator, enabling the generation of new regressions with specific targets. The Verisium SimAI app also features cousin bug hunting, a unique capability that uses information from difficult-to-hit failures to expose cousin bugs. With these advanced machine learning techniques, Verisium SimAI offers the potential for a significant boost in productivity, promising an exciting future for our users.

Figure 1: Regression compression and coverage maximization with Verisium SimAI 

What can I do with Verisium SimAI?

You can exercise different use cases with Verisium SimAI as per your requirements. For some users, the goal might be regression compression and improving coverage regain. Coverage maximization and hitting new bins could be another goal. Other users may be interested in exposing hard-to-hit failures, bug hunting for difficult to find issues. Verisium SimAI allows users to take on any of these challenges to achieve the desired results.

Let's go into some more details of these use cases and scenarios where using SimAI can have a big positive impact.

1. Using SimAI for Regression Compression and Coverage Regain

Unlock up to 10X compute savings with SimAI!

Verisium SimAI can be used to compress regressions and regain coverage. This flow involves setting up your regression environment for SimAI, running your random regressions with coverage and randomization data followed by training, and finally, synthesizing and running the SimAI-generated compressed regressions. The synthesized regression may prune tests that do not help meet the goal and add more runs for the most relevant tests, as well as add run-specific constraints. This flow can also be used to target specific areas like areas involving a high code churn or high complexity.

You can check out the details of this flow with illustrative examples in the following Rapid Adoption Kits (RAK) available on the Cadence Learning and Support Portal (Cadence customer credentials needed):

• Using SimAI with vManager (For Regression Compression and Coverage Regain) (RAK) 
• Using SimAI with a Generic Runner (For Regression Compression and Coverage Regain) (RAK)

2. Using SimAI for Coverage Maximization and Targeting coverage holes

Reduce your Functional Coverage Holes by up to 40% using SimAI!

Verisium SimAI can be used for iterative coverage maximization. This is most effective when regressions are largely saturated, and SimAI will explicitly try to hit uncovered bins, which may be hard-to-hit (but not impossible) coverage holes. This is achieved using iterative learning technology where with each iteration, SimAI does some exploration and determines how well it performed. This technique can also be used for bug hunting by using holes as targets of interest.

See more details on the Cadence Learning and Support Portal:

• Using SimAI for Coverage Maximization - vManager flow (RAK) 
• Using SimAI for Coverage Maximization - Generic Runner Flow (RAK)

3. Using SimAI for Bug Hunting

Discover and fix bugs faster using SimAI!

Verisium SimAI has a new bug hunting flow which can be used to target the goal of exposing hard-to-hit failure conditions. This is achieved using an iterative framework and by targeting failures or rare bins. The goal to target failures is best exercised when the overall failure rate is typically low (below 5%). Iterative learning can be used to improve the ability to target specific areas. Use the SimAI bug hunting use case to target rare events, low hit coverage bins, and low hit failure signatures.

See more details on the Cadence Learning and Support Portal:

• Using SimAI for Bug Hunting with vManager (RAK) 
• Using SimAI for Bug Hunting – Generic runner flow (RAK) 

Unlock compute savings, reduce your functional coverage holes, and discover and fix bugs faster with the power of machine learning technology now enabled by Verisium SimAI!

Please keep visiting  https://support.cadence.com/raks to download new RAKs as they become available.

Please note that you will need the Cadence customer credentials to log on to the Cadence Online  Support  https://support.cadence.com/, your 24/7 partner for getting help in resolving issues related to Cadence software or learning Cadence tools and technologies.

Happy Learning!

As technology continues to evolve at a rapid pace, the importance of robust and efficient interconnect standards cannot be overstated. Peripheral Component Interconnect Express (PCIe) has been a cornerstone in high-speed data transfer, enabling seamless communication between various hardware components.   

With the advent of PCIe 6.1 ECN, a significant advancement in speed and efficiency, ensuring the accuracy and reliability of its operations is paramount. One critical aspect of this is the verification of shared credit updates. For detailed understanding on Shared Credit, please refer Understanding PCIe 6.0 Shared Flow Control. 

In this blog, we will discuss why this verification is essential and what it entails.  

Introduction 

PCIe 6.1 ECN brings numerous advancements over earlier versions, such as increased bandwidth and faster data transfer speeds.   

A crucial mechanism for efficient data transmission in PCIe 6.0 is the credit-based flow control system. In this system, devices monitor credits, representing the buffer capacity available for incoming data.   

When a device transmits data, it uses credits, which are replenished or adjusted once the data is received and processed. This system ensures that the sender does not overload the receiver.  

Given the critical role of shared credit updates in maintaining the integrity and efficiency of data transfers, verification of these updates is crucial.  Proper management of credit updates is essential to ensure data integrity, as any discrepancies can lead to data loss, corruption, or system crashes.   

Verification also guarantees efficient resource allocation, preventing scenarios where some components are starved of credit while others have an excess, thus avoiding inefficiencies.  Credit inefficiencies pose issues in low power negotiations by preventing devices from entering low power states. Additionally, verification involves checking for proper error handling mechanisms, ensuring that the system can recover gracefully from errors in credit updates and maintain overall stability.   

PCIe 6.1 ECN Flow Control Optimizations Over PCIe 6.0

PCIe 6.1 ECN builds on the FLIT-based architecture introduced in PCIe 6.0, further optimizing flow control mechanisms to handle increased data rates and improved efficiency.  PCIe 6.1 ECN introduced refinements in credit management, making the allocation and advertisement of credits more precise, which helps in reducing bottlenecks and improving data flow efficiency.  Enhancements in flow control protocols ensure better management of buffer spaces and more efficient credit allocation. These enhancements are designed to handle the increased data rates and throughput demands of next-generation applications, ensuring robust and efficient data flow across PCIe devices.  

Below are some major updates: 

1. There have been improvements in error detection and correction mechanisms in PCIe 6.1 ECN to enhance flow control reliability by ensuring that corrupted data packets are detected and handled appropriately without disrupting the flow of valid packets.  
2. The merged credit system, which was a key feature introduced int PCIe 6.0 to simplify and optimize credit management, was further enhanced in PCIe 6.1 ECN to improve performance and efficiency.  
3. PCIe 6.1 ECN introduced better algorithms for allocating and reclaiming merged credits to handle high data rates, introduced more robust error detection and correction mechanism reducing the degradation or system instability. 
4. PCIe 6.1 ECN provided clear guidelines on how to implement the merged credit system correctly, helping developers to implement more reliable systems. For more details, please refer to Specifications section 2.6.1 Flow Control (FC) Rules.

Summary 

In summary, PCIe 6.0 is a complex protocol with many verification challenges. You must understand many new Spec changes and think about the robust verification plan for the new features and backward compatible tests impacted by new features. Cadence’s PCIe 6.0 Verification IP is fully compliant with the latest PCIe Express 6.0 specifications and provides an effective and efficient way to verify the components interfacing with the PCIe 6.0 interface. Cadence VIP for PCIe 6.0 provides exhaustive verification of PCIe-based IP and SoCs, and we are working with early adopter customers to speed up every verification stage.   

More Information

For more info on how Cadence PCIe Verification IP and Triple Check VIP enable users to confidently verify PCIe 6.0, see VIP for PCI Express, VIP for Compute Express Link  and TripleCheck for PCI Express    

See the PCI-SIG website for more details on PCIe in general and the different PCI standards.  

For more information on PCIe 6.0 new features, please visit PCIeLaneMargin, PCIe6.0LaneMargin, and Demonstrating PCIe 6.0 Equalization Procedure.

The Cadence Palladium Emulation Platform is a hardware system that implements the design, accelerating its execution and verification. Itoffers the highest performance and fastest bring-up times for pre-silicon validation of billion-gate designs, using a custom processor built by Cadence.

This Palladium Introduction course is based on the Palladium 23.03 ISR4 version and covers the following modules:

• Introduction
• Palladium flow
• Running a design on the Palladium system

This course starts with an “Introduction” module that explains Palladium and other verification platforms to show its place in the big picture. It also compares Palladium with Protium and simulation and discusses its usage and limitations.

The “Palladium Flow” module includes two stages at a high level, which are Compile and Run. Then, it covers these stages in detail. First, it covers the ICE compile flow and IXCOM compile flow steps in detail. Then it explains Run, which is common for both ICE and IXCOM modes.

The third module, “Running Design on the Palladium System,” covers all the items required for running your design on the Palladium system, including:

• Software stack requirements
• Basic concepts required to understand the flow
• Compute machine requirements

In addition, this course contains labs for both the ICE and IXCOM flows with detailed steps to exercise the features provided by the Palladium system. The lab explains a practical example of multiple counters and exercising their signals for force, monitor, and deposit features, along with frequency calculation using a real-time clock. The course is available on the Cadence support page:

There is also a Digital Badge available. You will find the Badge exam opportunity when you enroll in the Online training or after you have taken the training as "live" training.

For questions and inquiries, or issues with registration, reach out to us at Cadence Training. Want to stay up to date on webinars and courses? Subscribe to Cadence Training emails. To view our complete training offerings, visit the Cadence Training website.

Related Training Bytes

• Palladium: What Are Verification Platforms
• Palladium: What Is Processor Based Emulation
• Palladium: Comparing Emulation (Z2) and Prototyping (X2)
• Palladium: What Are ICE and IXCOM Compile Flow
• Palladium: How to Process a Design to Run on Palladium
• Palladium: XCOM Compile Flow (TB+RTL to Palladium Database)
• Palladium: ICE Compile Flow (RTL to Palladium Database)
• Palladium: Legacy ICE Compile Flow
• Palladium: Cadence Software Releases for Palladium and Protium Flow
• Palladium: Setting of PATHs for Using Palladium
• Palladium: Z2 Hardware Structure (Blade and Boards)
• Palladium: What Is Sourceless and Loadless nets
• Palladium: Design Clocks
• Palladium: Step Count and Step Clock
• Palladium: Steps for Running the Design on Palladium Z2

Related Courses

• Verilog Language and Application Training
• SystemVerilog for Design and Verification
• Xcelium Simulator

Related Blogs

• Training Insights – A New Free Online Course on the Protium System for Beginner and Advanced Users
• It’s the Digital Era; Why Not Showcase Your Brand Through a Digital Badge!
• Training Insights - Free Online Courses on Cadence Learning and Support Portal

DDR5 is the latest generation of PCDDR memory that is used in a wide range of application like data centers, Laptops and personal computers, autonomous driving systems, servers, cloud computing, and gaming are now increasingly being used for AI applications with advances in memory bandwidth and density to allow DDR5 DIMMs (Dual Inline Memory Modules) to support densities higher then 256 GB per DIMM card. The highest speed DDR5 SDRAM devices can support data rates of up to 8800 MTps.

DDR5 SO-DIMMs and UDIMMs

One of the most recognized uses of PCDDR is with client devices like laptops and personal computers. These client devices mostly use two types of DDR5 DIMMs called SO-DIMM (Small Outline Dual Inline Memory Module) and UDIMM (Unbuffered Dual Inline Memory Module).

These types of DIMMs have no signal regeneration or buffering (which, for example, the Registering Clock Driver or the RCD does for clocks/command/control signals for a registered DIMMs). A typical 2-Rank UDIMM with x8 DDR5 SDRAM components has 8 or 10 components per rank depending on the system ECC (Error Correction Code) memory being part of the DIMM.

Why DDR5 Clock Buffer and CUDIMM?

Clocks are one of the most important signals for synchronous devices, and DDR5 SDRAMs are no exception. The host is responsible for the fanout to all the DRAM input ports, such as clocks for UDIMMs. Driving of all these DRAM clocks can put quite a bit of load on the host output drivers, thus affecting the signal quality, which can result in unexpected memory errors. This issue gets amplified when operating at the higher clock and data rates where the clock signals transition from one logic value to the next over a very short time. To solve these signal integrity issues with DRAM clocks, JEDEC has come up with a new type of DDR5 DIMM component that is called DDR5 clock buffer. Clock buffers can be used for both DDR5 SO-DIMMs and DDR5 UDIMMs. DDR5 UDIMMs that include a clock buffer component as part of the DIMM card are called DDR5 CUDIMMs (Clock Buffered UDIMMs).

DDR5 Clock Buffer Overview

DDR5 Clock Buffer is a simple logic device that takes in two sets of input clock pins and drives two sets of clock pins as output per channel. The clock buffer device can operate in three types of clock modes: -

• PLL bypass mode: In this mode, the clock buffer just passes on the input clocks to output without any kind of signal buffering. The PLL bypass mode enabled CUDIMM devices behave like traditional UDIMMs without any buffering of the clocks. This is why it’s also referred to as legacy mode. Recommended CUDIMM operating speeds in PLL bypass mode are typically limited to 3000 MHz.

• Single PLL mode: In the single PLL Mode, the clock buffer device will use a Phase Lock Loop (PLL) for the regeneration of the incoming host clock to create a better-quality clock that is sent to the DRAMs. However, since there is only one PLL that is used in this mode, both sub channel output clocks will be driven based on only one set of input clocks with the other set of input clocks remaining unused.

• Dual PLL mode: In this mode, the clock buffer will use two PLLs to independently generate each sub channel output clock based on each set of incoming host clocks. The second set of PLL can be turned on or off on the fly if needed to save power.

Beyond the clock modes, clock buffers provide additional flexibility to the system designers with register-controlled additional signal delays, optional output clock enable/disable per bit feature, drive strength and termination choices, etc. All DDR5 clock buffer device control word registers are accessible via DDR5 DIMM sideband.

Cadence VIPs offers a compressive memory subsystem solution that includes memory models for DDR5 SDRAM, DDR5 RCD, DDR5 DB, DDR5 clock buffer, all types of DDR5 DIMMs, including the DDR5 CUDIMMs, DFI Memory Controller/PHY VIPs, and a system VIP compliant to JEDEC specifications defined for each of those devices along with latest DFI Specification.

More information on Cadence DDR5 DIMM VIP is available at the Cadence VIP Memory Models website.

The course "Jasper Formal Fundamentals v24.03" introduces formal analysis to those who want to use formal analysis for design or verification. 

To optimally benefit from this course, you must already have sufficient knowledge of the System Verilog assertions to be capable of writing properties for formal verification. Hence, this training provides a module on formal analysis to help cover this essential background. 

In this course, you will learn how to code efficient SVA Properties for formal analysis, understand formal complexity and how to overcome it, and learn the basics of formal coverage.

After completing this course, you will be able to:

• Define reusable, functionally correct SVA properties that are efficient for formal tools. These shall use abstract auxiliary code to simplify descriptions, make code maintenance easier, reduce debug time, and reduce tool-proof runtime.
• Set up, run, and analyze results from formal analysis.
• Identify designs upon which formal is likely to be successful while understanding formal complexity issues and how to identify and overcome them.
• Use a systematic property development process to approach a completely new verification problem.
• Understand the basics of formal coverage.

 The most recently updated release includes new modules on:

• "Basic complexity handling" which discusses the complexity in formal and how to identify and handle them.
• "Complexity reduction methods” which discusses the complexity reduction methods and which is suitable for which type of complexity problem.
• “Coverage in formal” which discusses the basics of coverage in formal verification and how coverage can be used in formal.   

Take this course to learn the basics of formal verification. 

What's Next? 

You can check out the complete training: Jasper Formal Fundamentals. There is a free online version of the training available 24/7 for all customers with a Cadence Learning and Support Portal account. If you are interested in an instructor-led version of the training, please contact Cadence Training. And don't forget to obtain your digital badge after completing the training!

You can also check Jasper University page for more materials on formal analysis and Jasper apps. 

Related Trainings 

Jasper Formal Expert Training Course | Cadence

Verilog Language and Application Training Course | Cadence

SystemVerilog for Design and Verification Training Course | Cadence

SystemVerilog Assertions Training Course | Cadence

Related Training Bytes 

Jasper Formal Property Verification (FPV) App: Basic Usage Demo (Video)

Jasper Formal Methodology playlist

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It’s the Digital Era; Why Not Showcase Your Brand Through a Digital Badge!

Training Insights: Introducing the C++ Course for All Your C++ Learning Needs!

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Training Insights - Free Online Courses on Cadence Learning and Support Portal

Cadence PCIe/CXL VIP support for Partial Header Encryption in Integrity and Data Encryption.(read more)

Verisium Debug, the Cadence unified debug platform, offers a variety of debugging capabilities, including RTL debug, UVM testbench debug, UPF debug, and DMS debug. From IP to SoC level debug, the user can take the benefits of the rich debugging features to reduce the time for debug.

Not only the common and advanced debug features, Verisium Debug also provides Python-based interface API, which enables capabilities allowing users to customize functions with Verisium Debug Python API to access from design, waveform databases and add functions to Verisium Debug’s GUI for visualization purposes. With Verisium Debug’s Python API, users can turn repetitive works into automatic programs or reduce efforts to create in-house utilities with well-established infrastructure from Verisium Debug.

Here is an example of how the user uses Python API to create a customized function. Users can write a Python program to extract signals in a specific design scope and report the values of the extracted signals. From Fig 1., you can understand the procedure of the traversal steps.

1. Import Python library in Verisium Debug package.
2. Setup the database for traversal.
3. Search the scope with the hierarchy information in the design DB.
4. Query the signal list and the values of the signals.
5. Print out the results.

Fig 1. Procedure of Verisium Debug Python Program

The result from the Verisium Debug Python App can be used for post-process design checking or fed into other utilities in the design flow.

The concept is very straightforward. With Verisium Debug and the Python API environment enabled, you can easily query any information that is stored in the databases of Verisium Debug. The result can be outputted in text format, or you can also use the API to display the results back to Verisium Debug’s GUI.

The Verisium Debug Python API is an important capability and resource for Verisium Debug users. To make Verisium Debug Python API easier to access, from Verisium Debug 24.10 release, Verisium Debug introduced the new Verisium Debug Python App Store.

Fig 2. Verisium Debug App Store

The Python App Store includes ready-to-use Python App examples with the availabilities of original source code documents, which help the user to understand how to start writing an app that fits their use case.

Fig 3. Example apps in Verisium Debug App Store

The Verisium Debug Python App Store can also be used by a team as an app management system. App creators can share the developed apps across teams within their companies. The in-house created apps will become easy to manage, and engineers can easily access the apps from the central location, which makes it possible for users to see the updated available Verisium Debug Apps from the Verisium Debug App Store.

Check the following videos for more information about Verisium Debug Python API:

Customize Verisium Debug with Python API

Verisium Debug Customized Apps with Python API

In SoC development, the verification cycle is a crucial phase that ensures products meet their specifications and function correctly. However, the complexity of modern SoC projects, with their constant data flow, multiple validation teams working in parallel, and tight schedules, presents significant challenges. This article explores these challenges and introduces Verisium Manager as a solution that embodies the 'One Tool Fits All' concept. This means that Verisium Manager is designed to handle all aspects of the verification process for SoC development, from planning to coverage analysis to regression testing, thereby addressing the complex needs of SoC verification.

The Hurdles in Traditional Validation Cycles

 A typical validation process involves planning, coverage analysis, and regression testing. This complexity is compounded by using separate tools for each activity, leading to multiple control environments, APIs, and databases, not to mention the array of tool owners. Such fragmentation results in constant data transfer and translation between systems, from the planning tool to the coverage analysis tool and then to the regression testing tool. This continuous movement of data causes delays, system instability, poor user experiences, and, ultimately, a dip in the quality of the validation process.

The use of multiple platforms leads to inefficiency and reduced productivity. What's needed is a unified system that can streamline the workflow, simplify the verification process, and enhance its effectiveness.

Envisioning the Ideal Solution: Verisium Manager

 The cornerstone of an efficient validation cycle is integration and simplicity. The ideal solution is a singular platform that consolidates planning, coverage analysis, and regression management into one smooth, unified process. Verisium Manager emerges as this much-needed solution, encompassing all the functionalities necessary to streamline the validation process. Its comprehensive nature instills confidence in its ability to handle all aspects of the verification cycle. It can be fully customized to address and enforce any validation methodology and can facilitate smooth integration into any customer environment.

Features that stand out in Verisium Manager include: 

• Unified Workflow: It acts as a single cockpit from which all activities are orchestrated, ensuring the validation teams' work is uninterrupted and seamlessly integrated.
• Customization and Integration: Verisium Manager supports customizing test-plan structures and mapping results per project, ensuring a perfect fit for various project requirements. Its ability to smoothly integrate into the project's environment and compute platforms is unparalleled.
• Support for Continuous Updates and Migration: The tool accommodates constant updates to project data and supports the migration of legacy data, ensuring that no historical data is lost in the transition to a new system.

Addressing Project-Specific Needs

 Verisium Manager recognizes diversity in different projects and offers project-specific solutions, including:

 Enforcing Project Test-Plan Structures and Attributes: It supports and enforces each project's unique test-plan structure and mapping guidelines.

• Unified Data Views and Measurements: Verisium Manager promotes a unified view of data across all teams and enforces unified measurements, ensuring consistency and clarity in the validation process.
• Enabling Project-Specific Actions and Integrations: The tool is designed to support project-specific actions directly from its graphical user interface and allows for smooth integration with in-house databases, dashboards, and the project execution stack.

Verisium Manager is the epitome of efficiency in software/hardware validation. Its differentiating features, such as support for customization, unified data view, and comprehensive coverage and regression requirements, make it an indispensable tool for any validation team looking to elevate their workflow.

PHY Interface for the PCI Express (PCIe), SATA, USB, DisplayPort, and USB4 Architectures (PIPE) enables the development of the Physical Layer (PHY) and Media Access Layer (MAC) design separately, providing a standard communication interface between these two components in the system.

In recent years, the PIPE interface specification has incorporated many enhancements to support new features and advancements happening in the supported protocols. As the supported features increase, so does the count of signals on PIPE interface. To address the issue of increasing signal count, the message bus interface was introduced in PIPE 4.4 and utilized for PCIe lane margining at the receiver and elastic buffer depth control.

In PIPE 5.0, all the legacy PIPE signals without critical timing requirements were mapped into message bus registers so that their associated functionality could be accessed via the message bus interface instead of implementing dedicated signals. It was decided that any new feature added in the new version of PIPE specification will be available only via message bus accesses unless they have critical timing requirements that need dedicated signals.

Message Bus Interface

The message bus interface provides a way to initiate and participate in non-latency-sensitive PIPE operations using a small number of wires. It also enables future PIPE operations to be added without adding additional wires. The use of this interface requires the device to be in a power state with PCLK running.

Control and status bits used for PIPE operations are mapped into 8-bit registers that are hosted in 12-bit address spaces in the PHY and the MAC. The registers are accessed using read-and-write commands driven over the signals M2P_MessageBus[7:0] and P2M_MessageBus[7:0]. These signals are synchronous with the PCLK and are reset with Reset#.

Message Bus Interface Commands

The 4-bit commands are used for accessing the PIPE registers across the message bus. A transaction consists of a command and any associated address and data.

All the following are time multiplexed over the bus from MAC and PHY:

1. Commands (write_uncommitted, write_committed, read, read completion, write_ack)
2. 12-bit address used for all types and read and writes
3. 8-bit data, either read or written

There can be cases where multiple PIPE interface signals can change on the same PCLK. To address such cases, the concept of write_uncommitted and write_committed is introduced.

The uncommitted write should be saved into a write buffer, and its associated data values are updated into the relevant PIPE register at a future time when a write_committed is received, taking effect during the same PCLK cycle. Once a write_committed is sent, no new writes, whether committed or uncommitted, and any read command may be sent until a write_ack is received. Also, it is allowed to send NOP commands between write uncommitted and write committed. 

A simple timing demonstration of message bus:

Message Address Space

MAC and PHY each implement unique 12-bit address spaces. These address spaces will host registers associated with the PIPE operations. MAC accesses PHY registers using M2P_MessageBus[7:0], and PHY accesses the MAC registers using the M2P_MessageBus[7:0].

The MAC and PHY access specific bits in the registers to: initiate operations, Initiate handshakes, and Indicate status.

Each 12-bit address space is divided into four main regions: the receiver address region, the transmitter address region, the common address region, and the vendor-specific address region.

Each register field has an attribute description of either level or 1-cycle assertion. When a level field is written, the value written is maintained by the hardware until the next write to that field or until a reset occurs. When a 1-cycle field is written to assert the value high, the hardware maintains the assertion for only a single cycle and then automatically resets the value to zero on the next cycle.

Cadence has a mature Verification IP solution for the verification of various aspects and topologies of PIPE PHY design. For more details, you may refer to the Simulation VIP for PIPE PHY | Cadence page, or you may send an email to support@cadence.com.

The application of real-time data processing or responsiveness is crucial, such as in high-performance computing, data centers, or applications requiring low-latency data transfers. It enables efficient use of PCIe bandwidth and resources by intelligently managing memory write operations based on system dynamics and workload priorities. By effectively leveraging Deferrable Memory Write [DMWr], Devices can achieve optimized performance and responsiveness, aligning with the evolving demands of modern computing applications.

What Is Deferrable Memory Write?

Deferrable Memory Write (DMWr) ECN introduced this new memory transaction type, which was later officially incorporated in PCIe 5.0 to CXL2.0. This enhanced type of memory transaction is Deferrable Memory Write [DMWr], which flows as another type of existing Read/Write memory transaction; the major difference of this Deferrable Memory Write, where the Requester attempts to write to a given location in Memory Space using the non-posted DMWr TLP Type, it Postponing their completion of memory write transactions to improve overall system efficiency and performance, those memory write operation can be delay or deferred until other priority task complete.

The Deferrable Memory Write (DMWr) requires the Completer to return an acknowledgment to the Requester and provides a mechanism for the recipient to defer (temporarily refuse to service) the Request.

DMWr provides a mechanism for Endpoints and hosts to choose to carry out or defer incoming DMWr Requests. This mechanism can be used by Endpoints and Hosts to simplify the design of flow control, reduce latency, and improve throughput. The Deferrable Memory writes TLP format in Figure A.

(Fig A) Deferrable Memory writes TLP format.

Example Scenario

Here's how the DMWr works with a simplified example: Imagine a system with an endpoint device (Device A) and a host CPU (Device B). Device B wants to write data to Device A's memory, but due to varying reasons such as system bus congestion or prioritization of other transactions, Device A can defer the completion of the memory write request. Just follow these steps:

1. Initiation of Memory Write: Device B initiates a memory write transaction to Device A. This involves sending the memory write request along with the data payload over the PCIe physical layer link.
2. Acknowledgment and Deferral: Upon receiving the memory write request, Device A acknowledges the transaction but may decide to defer its completion. Device A sends an acknowledgment (ACK) back to Device B, indicating it has received the data and intends to complete the write operation but not immediately.
3. Deferred Completion: Device A defers the completion of the memory write operation to a later, more opportune time. This deferral allows Device A to prioritize other transactions or optimize the use of system resources, such as memory bandwidth or processor availability.
4. Completion and Response: At a later point, Device A completes the deferred memory write operation and sends a completion indication back to Device B. This completion typically includes any status updates or additional information related to the transaction.

Usage or Importance of DMWr

Deferrable Memory Write usage provides the improvement in the following aspects:

• Reduced Latency: By deferring less critical memory write operations, more critical transactions can be processed with lower latency, improving overall system responsiveness.
• Improved Efficiency: Optimizes the utilization of system resources such as memory bandwidth and CPU cycles, enhancing the efficiency of data transfers within the PCIe architecture.
• Enhanced Performance: Allows devices to manage and prioritize transactions dynamically, potentially increasing overall system throughput and reducing contention.

Challenges in the Implementation of DMWr Transactions

The implementation of deferrable memory writes (DMWr) introduces several advancements and challenges in terms of usage and verification:

1. Timing and Synchronization: DMWr allows transactions to be deferred, complicating timing requirements or completing them within acceptable timing windows to avoid protocol violations. Ensuring proper synchronization between devices becomes critical to prevent data loss or corruption.
2. Protocol Compliance: Verification must ensure compliance with ECN PCIe 6.0 and CXL specifications regarding when and how DMWr transactions can be initiated and completed.
3. Performance Optimization: While DMWr can improve overall system performance by reducing latency, verifying its impact on system performance and ensuring it meets expected benchmarks is crucial.
4. Error Handling: Handling errors related to deferred transactions adds complexity. Verifying error detection and recovery mechanisms under various scenarios (e.g., timeout during deferral) is essential.

Verification Challenges of DMWr Transactions

The challenges to verifying the DMWr transaction consist of all checks with respect to Function, Timing, Protocol compliance, improvement, Error scenario, and security usage on purpose, as well as Data integrity at the PCIe and CXL.

1. Functional Verification: Verifying the correct implementation of DMWr at both ends of the PCIe link (transmitter and receiver) to ensure proper functionality and adherence to specifications.
2. Timing Verification: Validating timing constraints associated with deferring writes and ensuring transactions are completed within specified windows without violating protocol rules.
3. Protocol Compliance Verification: Checking that DMWr transactions adhere to PCIe and CXL protocol rules, including ordering rules and any restrictions on deferral based on the transaction type.
4. Performance Verification: Assessing the impact of DMWr on overall system performance, including latency reduction and bandwidth utilization, through simulation and testing.
5. Error Scenario Verification: Creating and testing scenarios to verify error handling mechanisms related to DMWr, such as timeouts, retries, and recovery procedures.
6. Security Considerations: Assessing potential security vulnerabilities related to DMWr, such as data integrity risks during deferred transactions or exposure to timing-based attacks.

Major verification challenges and approaches are timing and synchronization verification in the context of implementing deferrable memory writes (DMWr), which is crucial due to the inherent complexities introduced by deferred transactions. Here are the key issues and approaches to address them:

Timing and Synchronization Issues

1. Transaction Completion Timing:
   • Issue: Ensuring deferred transactions are completed within the specified time window without violating protocol timing constraints.
   • Approach: Design an internal timer and checker to model worst-case scenarios where transactions are deferred and verify that they are complete within allowable latency limits. This involves simulating various traffic loads and conditions to assess timing under different scenarios.
2. Ordering and Dependencies:
   • Issue: Verifying that transactions deferred using DMWr maintain the correct ordering and dependencies relative to non-deferred transactions.
   • Approach: Implement test scenarios that include mixed traffic of DMWr and non-DMWr transactions. Verify through simulation or emulation that dependencies and ordering requirements are correctly maintained across the PCIe link.
3. Interrupt Handling and Response Times:
   • Issue: Verify the handling of interrupts and ensure timely responses from devices involved in DMWr transactions.
   • Approach: Implement test cases that simulate interrupt generation during DMWr transactions. Measure and verify the response times to interrupts to ensure they meet system latency requirements.

In conclusion, while deferrable memory writes in PCIe and CXL offer significant performance benefits, their implementation and verification present several challenges related to timing, protocol compliance, performance optimization, and error handling. Addressing these challenges requires rigorous testing and testbench of traffic, advanced verification methodologies, and a thorough understanding of PCIe specifications and also the motivation behind introducing this Deferrable Write is effectively used in the CXL further. Outcomes of Deferrable Memory Write verify that the performance benefits of DMWr (reduced latency, improved throughput) are achieved without compromising timing integrity or violating protocol specifications.

In summary, PCIe and CXL are complex protocols with many verification challenges. You must understand many new Spec changes and consider the robust verification plan for the new features and backward compatible tests impacted by new features. Cadence's PCIe 6.0 Verification IP is fully compliant with the latest PCIe Express 6.0 specifications and provides an effective and efficient way to verify the components interfacing with the PCIe 6.0 interface. Cadence VIP for PCIe 6.0 provides exhaustive verification of PCIe-based IP and SoCs, and we are working with Early Adopter customers to speed up every verification stage.

More Information

• For more info on how Cadence PCIe Verification IP and TripleCheck VIP enable users to confidently verify PCIe 6.0, see our VIP for PCI Express, VIP for Compute Express Link, and TripleCheck for PCI Express
• See the PCI-SIG website for more details on PCIe in general and the different PCI standards.