1 Papua New Guinean Kina = 6.4733 Slovak Koruna

1 Papua New Guinean Kina = 5.198 Moldovan Leu

1 Brunei Dollar = 7.067 Venezuelan Bolivar Fuerte

1 Brunei Dollar = 6.1925 Salvadoran Colon

1 Brunei Dollar = 15.7126 Slovak Koruna

1 Brunei Dollar = 12.6171 Moldovan Leu

Test chips are becoming more widespread and more complex at advanced process nodes as design teams utilize early silicon to diagnose problems prior to production. But this approach also is spurring questions about whether this approach is viable at 7nm and 5nm, due to the rising cost of prototyping advanced technology, such as mask tooling and wafer costs.

Semiconductor designers have long been making test chips to validate test structures, memory bit cells, larger memory blocks, and precision analog circuits like current mirrors, PLLs, temperature sensors, and high-speed I/Os. This has been done at 90nm, 65nm, 40nm, 32nm, 28nm, etc., so having test chips at 16nm, 7nm, or finer geometries should not be a surprise. Still, as costs rise, there is debate about whether those chips are over-used given advancements in tooling, or whether they should be utilized even more, with more advanced diagnostics built into them.

Modern EDA tools are very good. You can simulate and validate almost anything with certain degree of accuracy and correctness. The key to having good and accurate tools and accurate results (for simulation) is the quality of the foundry data provided. The key to having good designs (layouts) is that the DRC deck must be of high quality and accurate and must catch all the things you are not supposed to do in the layout. Most of the challenges in advanced node is in the FEOL where semiconductor physics and lithography play outsize roles. Issues that were not an issue at more mature nodes can manifest themselves as big problems at 7nm or 5nm. Process variation across the wafer and variation across a large die also present problems that were of no consequence in more mature nodes.

The real questions to be asked are as follows:

What is the role of test chips in SoC designs?

1. Do all hard IP require test chips for validation?
2. Are test chips more important at advanced nodes compared to more mature nodes?
3. Is the importance of test chip validation relative to the type of IP protocols?
4. What are the risks if I do not validate in silicon?

In complex SoC designs, there are many high-performance protocols such as LPDDR4/4x PHY, PCIe4 PHY, USB3.0 PHY, 56G/112G SerDes, etc. Each one of these IP are very complex in and by itself. If there is any chance of failure that is not detected prior to SoC (tapeout) integration, the cost of retrofit is huge. This is why the common practice is to validate each one of these complex IP in silicon before committing to use such IP in chip integration. The test chips are used to validate that the IP are properly designed and meet the functional specifications of the protocols. They are also used to validate if sufficient margins are designed into the IP to mitigate variances due to process tolerances. All high-performance hard IP go through this test chip/silicon validation process. Oftentimes, marginality is detected at this stage. In advanced nodes, it is also important to have the test chips built under different process corners. This is intended to simulate process variations in production wafers so as to maximize yields. Advanced protocols such as 112G, GDDR6, HBM2, and PCIe4 are incredibly complex and sensitive to process variations. It is almost impossible to design these circuits and try to guarantee their performance without going through the test chip route.

Besides validating performance of the IP protocols, test silicon is also used to validate robustness of ESD structures, sensitivity to latch up, and performance degradation over wide temperature ranges. All these items are more critical in advanced nodes than more mature modes. Test chips are vehicles to guarantee design integrity in bite-size chunks. It is better to deal with any potential issues in smaller blocks than to try to fix them in the final integrated SoC.

Test chips will continue to play a vital role in helping IP and SoC teams lower the risk of their designs, and assuring optimal quality and performance in the foreseeable future. They are not going away!

To read more, please visit https://semiengineering.com/test-chips-play-larger-role-at-advanced-nodes/

Is there a better approach to varying the coefficients of a digital IIR over time to adjust the values of its poles and zeros than just recalculating the whole thing every time it changes? For example, lots of synth programs can apply an LFO to the cutoff frequency of a low/high pass filter. I can do some polynomial multiplication to get the coefficients for an IIR filter given its poles and zeros, but am wondering if there is a better way to adjust them over time than simply doing all the calculations over again for new poles/zeros. Particularly, I'm curious if there is a method that will more or less work for an arbitrary number of poles and zeros. You could use a filter implementation (state space) that directly uses the pole/zero values instead of a polynomial walmartone. That might be computationally more expensive, though (as you are taking a trip through the domain of complex numbers even though your inputs and output are real), and possibly numerically iffy.As far as I am aware, modifying filter behavior while introducing as few artefacts as possible is still an area of research. You might get away with just adjusting the filter coefficients if you do it slowly, but this does not mean this is the best method.In an audio application, I assume they do not switch filter coefficients abruptly, but instead do a cross-fade between the (settled) first filter and the (mostly or completely settled) target filter to avoid audible artefacts.

For a netlist vs. netlist LEC flow we have to solve the following problem:

- in the RTL code we replicate a large array of N x M all-identical hard-macros, let call them MACRO_A

- MACRO_A is pre-assembled in Innovus and contains digital parts and analog parts (bottom-up hierarchical flow)

- at top-level (full-chip) we instantiate this array of all-identical macros

- in the top-level place-and-route flow we perform ecoChangeCell to remaster the top row of this array with MACRO_B

- MACRO_B is just a copy of the original MACRO_A cell containing same pins position, same internal digital functionality and also same digital layout, only slight differences in one analog block inside the macro

- MACRO_A and MACRO_B have the same .lib file generated with the do_extract_model command at the end of the Innovus flow, they only differ in the name of the macro

- when performing post-synthesis netlist vs post-place-and-route we load .lib files of both macros in Conformal LEC

- the LEC flow fails because Conformal LEC sees only MACRO_A instantiated in the post-synthesis netlist and both MACRO_A and MACRO_B in the post-palce-and-route netlist

Since both digital functionality and STD cells layout are the same between MACRO_A and MACRO_B we don't want to keep track of this difference already at RTL stage, we just want to perform this ECO change in place-and-route and force Conformal to assume equivalence between MACRO_A and MACRO_B .

Basically what I'm searching for is something similar to the add_instance_equivalences Conformal command but that works between Golden and Revised designs on cell primitives/black-boxes .

Is this flow supported ?

Thanks in advance

Luca

Hi,

I am running simulation in ADEXL and need a custom function for VIVA to apply same procedure to all signals saved in output. For instance, I have clock nets and I want to get all of them and look at the duty-cycle, edge rate etc.

It is a little more involved than about part since I have some regex and setof to filter before processing but if I can get all signals for current history, I can postprocess them later.

In ocean, I am just doing outputs() and getting all saved signals but I was able to do this in VIVA calculator due to the difficulties in getting current history, test name and opening result directory

thanks

yayla

Version Info:

ICADV12.3 64b 500.21

spectre -W =>

Tool 'cadenceMMSIM' Current project version '16.10.479'
sub-version  16.1.0.479.isr9

When I place a pcell and do not change the W parameter (default is used) the value is not saved in the OA cell property.

When I change the default value of the super master now, the old pcell will get the new default value automatically because there is nothing saved inside the OA cell for this parameter.

Do you have any Idea, that how we can save the default values in the OA cell properties so that this value doesn't get updated if the default values are updated in the new PDKs

Hi, I want to add values to components in my SiP design such as 1nF or 15nH. There is already in existence a COMP_VALUE property reserved for this as shown during BOM generation. This property is not visible under the Edit/Properties dialog for component or symbol find filters. We have already created user properties called COMP_MFG and COMP_MFG_PN that it editable at a component level. When we try to add COMP_VALUE it is reported as a reserved name in Cadence but this name is not listed in the properties dialog. Is there a way to turn on the visibility and editablility of this or other hidden reserved Cadence property names? How can I assign a string value to the COMP_VALUE property?

Thanks

The 2019 HF1 production release for Clarity, Celsius, and Sigrity Tools is now available for download at Cadence Downloads . SIGRITY2019 HF1 For information about supported platforms, compatibility...

[[ Click on the title to access the full blog on the Cadence Community site. ]]

We have talked about aspects of the in-design symbol edit application mode in the past. This is the environment specific to the Allegro® Package Designer Plus layout tools allowing you to work...

[[ Click on the title to access the full blog on the Cadence Community site. ]]

There is no better way other than a self-help training kit -- (rapid adoption kit, or RAK) -- to demonstrate the Incisive Enterprise Simulator's IEEE 1801 / UPF low-power features and its usage. The features include:

• Unique SimVision debugging 
• Patent-pending power supply network visualization and debugging
• Tcl extensions for LP debugging
• Support for Liberty file power description
• Standby mode support
• Support for Verilog, VHDL, and mixed language
• Automatic understanding of complex feedthroughs
• Replay of initial blocks
• ‘x' corruption for integers and enumerated types
• Automatic understanding of loop variables
• Automatic support for analog interconnections

Mickey Rodriguez, AVS Staff Solutions Engineer has developed a low power UPF-based RAK, which is now available on Cadence Online Support for you to download.

• This rapid adoption kit illustrates Incisive Enterprise Simulator (IES) support for the IEEE 1801 power intent standard. 

Patent-Pending Power Supply Network Browser. (Only available with the LP option to IES)

• In addition to an overview of IES features, SimVision and Tcl debug features, a lab is provided to give the user an opportunity to try these out.

The complete RAK and associated overview presentation can be downloaded from our SoC and Functional Verification RAK page:

We are covering the following technologies through our RAKs at this moment:

Synthesis, Test and Verification flow
Encounter Digital Implementation (EDI) System and Sign-off Flow
Virtuoso Custom IC and Sign-off Flow
Silicon-Package-Board Design
Verification IP
SOC and IP level Functional Verification
System level verification and validation with Palladium XP

Please visit https://support.cadence.com/raks to download your copy of RAK.

We will continue to provide self-help content on Cadence Online Support, your 24/7 partner for learning more about Cadence tools, technologies, and methodologies as well as getting help in resolving issues related to Cadence software. If you are signed up for e-mail notifications, you're likely to notice new solutions, application notes (technical papers), videos, manuals, etc.

Note: To access the above documents, click a link and use your Cadence credentials to log on to the Cadence Online Support https://support.cadence.com/ website.

Happy Learning!

Sumeet Aggarwal and Adam Sherer

Virtuoso Version -- IC6.1.7-64b.500.23

Cadence Spectre Version -- 17.10.515

I have a very simple circuit. Please find attached. It is basically a resistor across a port. I run a S-param simulation and can plot the S-params, but unfortunately not the Z-param or Y-param. 

/resized-image/__size/320x240/__key/communityserver-discussions-components-files/33/Capture_5F00_Sch.JPG

/resized-image/__size/320x240/__key/communityserver-discussions-components-files/33/Capture_5F00_Error.JPG

Can anyone point me in the correct direction to sort out this problem? The zpm does work in another design environment, but not in the new design environment (a new project). The virtuoso and the cadence-spectre versions match in both the project environments. I am at a loss at what to look for. 

Hello, There is a manual in matlab of matching LNA  shown in the link bellow.

In it as shown in the plot bellow they mention input and output circle plots.

Is there such option of input and output circle in cadence virtuoso?

https://www.mathworks.com/help/rf/examples/designing-matching-networks-part-1-networks-with-an-lna-and-lumped-elements.html

Hi Guys,

Anyone know equivalent skill for create detail.

Eugene

We have talked about aspects of the in-design symbol edit application mode in the past. This is the environment specific to the Allegro Package Designer layout tools allowing you to work on symbol definitions directly in the context of your layout de...(read more)

Hello all,

We are designing a backplane and in the design we are using some custom prefixes using the Advance Annotation tool. When annotating the occurances I get the following error:

ERROR(ORDBDLL-1224): The total number of components for prefix J0C exceeds the range supplied for it.
Increase the End value of the range.

Thanks in advance for the help

--Tom

Hi There,

The variant bom I set gone dissapear. Is there any way to recover this back from the old design file? 

This is the second time it happen to me. Not really sure what could cause this. 

Thanks,

Pornchai

Hello,

I have a question I want to create a cover that consists a sparse values, pre-computed (a list or define) for example l = {1; 4; 7; 9; 2048; 700} I'd like to cover that data a (uint(bits:16)) had those values, Any suggestion on how to achieve this, I'd prefer to stay away from macros, and avoid to write a lot of code

struct inst {

  data :uint(bits:16);
  opcode :uint(bits:16);
  !valid_data : list of uint(bits:16) = {0; 12; 10; 700; 890; 293;};
  event data_e;
  event opcode_e;

  cover data_e is {
     item data using radix = HEX, ranges = {
     //I dont want to write all of this
     range([0], "My range1");
     range([10], "My range2");
     //... many values in between
    range([700], "My rangen");
    };

    item opcode;

   cross data, opcode;
};

post_generate() is also {
    emit data_e;
};
};

Exporting a waveform into a vcsv file returns the error:

The wsSaveTraceCommand command generated an exception basic_string::_S_construct null not valid.

Only the first row of the vcsv file is created (";Version, 1, 0"). This was the first time I've exported waveforms generated with Assembler. I had no issue before with the combination of ADE L, Parametric sweep and ViVA XL. My project uses ICADV 12.3. I have not found any related forum entry or documentation. How could I export the waveforms in vcsv? Exporting the values into a table and then exporting into a csv works, but my post-processing script was written for vcsv format.

Hello,

I am trying to use calcVal for creating a spec condition from a simulated parameter and although this works perfectly fine in corner simulations, I am having some difficulties in Monte-Carlo (and I will explain).

(I have also read "Using calcVal() and its arguments with ADE Assembler" in Resources > Rapid Adoption Kits but couldn't find any relevant information that would help me address the "issue").

In the above example I am performing a MC simulation which has 2 corners of 10 runs each. I would like to get the minimum value of variable "OC_limit_thres" out of those 10 runs and pass it as my upper limit to a range argument for variable "OC_flag_thres", so the CPK can be calculated.

So the range statement should in reality be like this:

range 32m 44.34m (for corner 0)

range 32m 43.14m (for corner 1)

If I open the Detail - Transpose view in the Results tab, the calcVal("OC_limit_thres" "Currlim_TurnOn_C11") is calculated perfectly fine for each run but here I need one single value out of those 10 runs - in this case the minimum - in order for calcVal to evalute on multiple runs of 1 corner.

How can this be done please?

Thank you in advance for your time.

Hello,

I find a strange issue when using design variable -> right-click -> copy from cellview in assembler. Cadence version is IC618-64b. 500.9

In fact, I set the value of variable (e.g., AAA = 100), then after I right-click -> copy from cellview, AAA's is updated to other value. In my opinion "copy from cellview" should only update the missing variable to the list, but not change any variable value. 

Is there any mechanism could change variable value when using "copy from cellview"?

Thanks

Hi,

I am trying to characterize a D flip-flop for low voltage operation (0.6V) using Cadence Liberate (V16). This is a positive edge triggered D flip flop based on true-single-phase clocking scheme. After the characterization, the measurements reported for hold constraint arcs seem to deviate significantly from its (spectre) spice simulation.

The constraint and the power settings to the liberate are as follows : 

# -------------------------------------------- Timing Constraints --------------------------------------------------------------------------------
### Input waveform ###
set_var predriver_waveform 2;# 2=use pre-driver waveform
### Capacitance ###
set_var min_capacitance_for_outputs 1;# write min_capacitance attribute for output pins
### Timing ###
set_var force_condition 4
### Constraint ###
set_var constraint_info 2
#set_var constraint_search_time_abstol 1e-12 ;# 1ps resolution for bisection search
set_var nochange_mode 1 ;# enable nochange_* constraint characterization
### min_pulse_width ###
set_var conditional_mpw 0
set_var constraint_combinational 2

#---------------------------------------------- CCS Settings ----------------------------------------------------------------------------------------
set_var ccsn_include_passgate_attr 1
set_var ccsn_model_related_node_attr 1
set_var write_library_is_unbuffered 1

set_var ccsp_min_pts 15 ;# CCSP accuracy
set_var ccsp_rel_tol 0.01 ;# CCSP accuracy
set_var ccsp_table_reduction 0 ;# CCSP accuracy
set_var ccsp_tail_tol 0.02 ;# CCSP accuracy
set_var ccsp_related_pin_mode 2 ;# use 3 for multiple input switching scnarios and Voltus only libraries

#----------------------------------------------- Power ---------------------------------------------------------------------------------------------------
### Leakage ###
set_var max_leakage_vector [expr 2**10]
set_var leakage_float_internal_supply 0 ;# get worst case leakage for power switch cells when off
set_var reset_negative_leakage_power 1 ;# convert negative leakage current to 0

### Power ###
set_var voltage_map 1 ;# create pg_pin groups, related_power_pin / related_ground_pin
set_var pin_based_power 0 ;# 0=based on VDD only; 1=power based on VDD and VSS (default);
set_var power_combinational_include_output 0 ;# do not include output pins in when conditions for combinational cells

set_var force_default_group 1
set_default_group -criteria {power avg} ;# use average for default power group

#set_var power_subtract_leakage 4 ;# use 4 for cells with exhaustive leakage states.
set_var subtract_hidden_power 2 ;# 1=subtract hidden power for all cells
set_var subtract_hidden_power_use_default 3 ;# 3=subtract hidden power from matched when condition then default group
set_var power_multi_output_binning_mode 1 ;# binning for multi-output cell considered for both timing and power arcs
set_var power_minimize_switching 1
set_var max_hidden_vector [expr 2**10]
#--------------------------------------------------------------------------------------------------------------------------------------------------------------

I specifically used set_var constraint_combinational 2 in the settings, in case the Bisection pass/fail mode fails to capture the constraints. In my spice simulation, the hold_rise (D=1, CLK=R, Q=R) arc at-least requires ~250 ps for minimum CLK/D slew combination (for the  by default smallest capacitive load as per Liberate)  while Liberate reports only ~30 ps. The define_cell template to this flip flop is pretty generic, which does not have any user specified arcs. So which settings most likely affecting the constraint measurements in Liberate and how can I debug this issue ?

Thanks

Anuradha

Hello,

I am using Virtuoso 6.1.7.

I am performing the parasitic extraction of a MOM cap array of 32 caps. I use Quantus QRC and I enable field solver. I select “QRCFS” for field solver type and “High” for field solver accuracy. The unit MOM cap is horizontally and vertically symmetric. The array looks like the sketch below and there are no other structures except the unit caps:

Rationally speaking, the capacitance values of the unit caps should be symmetric with respect to a vertical symmetry axis that is between cap16 and cap17 (shown with dashed red line). For example,

the capacitance of cap1 should be equal to the capacitance of cap32

the capacitance of cap2 should be equal to the capacitance of cap31

etc. as there are no other structures around the caps that might create some asymmetry.

Nevertheless, what I observe is the following after the parasitic extraction:

As it can be seen, the result is not symmetric contrary to what is expected. I should also add that I do not observe this when I perform parasitic extraction with no filed solver.

Why do I get this result? Is it an artifact resulting from the field solver tool (my conclusion was yes but still it must be verified)? If not, how can something like this happen?

Many thanks in advance.

Best regards,

Can

In this blog, I will brief you about two very useful Rapid Adoption Kits (RAKs) for Liberate LV Library Validation.(read more)

Key Findings: Advantest, in mixed-signal SoC design, sees 50X speedup, 25 day test reduced to 12 hours, dramatic test coverage increase.

Trolling through the CDNLive archives, I discovered another gem. At the May 2013 CDNLive in Munich, Thomas Henkel and Henriette Ossoinig of Advantest presented a paper titled “Timing-accurate emulation of a mixed-signal SoC using Palladium XP”. Advantest makes advanced electronics test equipment. Among the semiconductor designs they create for these products is a test processor chip with over 100 million logic transistors, but also with lots of analog functions.They set out to find a way to speed up their full-chip simulations to a point where they could run the system software. To do that, they needed about a 50X speed-up. Well, they did it!

Figure 1: Advantest SoC Test Products

To skip the commentary, read Advantest's paper here. 

Problem Statement

Software is becoming a bigger part of just about every hardware product in every market today, and that includes the semiconductor test market. To achieve high product quality in the shortest amount of time, the hardware and software components need to be verified together as early in the design cycle as possible. However, the throughput of a typical software RTL simulation is not sufficient to run significant amounts of software on a design with hundreds of millions of transistors.  

Executing software on RTL models of the hardware means long runs  (“deep cycles”) that are a great fit for an emulator, but the mixed-signal content posed a new type of challenge for the Advantest team.  Emulators are designed to run digital logic. Analog is really outside of the expected use model. The Advantest team examined the pros and cons of various co-simulation and acceleration flows intended for mixed signal and did not feel that they could possibly get the performance they needed to have practical runtimes with software testbenches. They became determined to find a way to apply their Palladium XP platform to the problem.

Armed with the knowledge of the essential relationship between the analog operations and the logic and software operations, the team was able to craft models of the analog blocks using reduction techniques that accurately depicted the essence of the analog function required for hardware-software verification without the expense of a continuous time simulation engine.

The requirements boiled down to the following:

• Generation of digital signals with highly accurate and flexible timing

• Complete chip needs to run on Palladium XP platform

• Create high-resolution timing (100fs) with reasonable emulation performance, i.e. at least 50X faster than simulation on the fastest workstations

Solution Idea

The solution approach chosen was to simplify the functional model of the analog elements of the design down to generation of digital signal edges with high timing accuracy. The solution employed a fixed-frequency central clock that was used as a reference.Timing-critical analog signals used to produce accurately placed digital outputs were encoded into multi-bit representations that modeled the transition and timing behavior. A cell library was created that took the encoded signals and converted them to desired “regular signals”. 

Automation was added to the process by changing the netlisting to widen the analog signals according to user-specified schematic annotations. All of this was done in a fashion that is compatible with debugging in Cadence’s Simvision tool.  Details on all of these facets to follow.

The Timing Description Unit (TDU) Format

The innovative thinking that enabled the use of Palladium XP was the idea of combining a reference clock and quantized signal encoding to create offsets from the reference. The implementation of these ideas was done in a general manner so that different bit widths could easily be used to control the quantization accuracy.

Figure 2: Quantization method using signal encoding

Timed Cell Modeling

You might be thinking – timing and emulation, together..!?  Yes, and here’s a method to do it….

The engineering work in realizing the TDU idea involved the creation of a library of cells that could be used to compose the functions that convert the encoded signal into the “real signals” (timing-accurate digital output signals). Beyond some basic logic cells (e.g., INV, AND, OR, MUX, DFF, TFF, LATCH), some special cells such as window-latch, phase-detect, vernier-delay-line, and clock-generator were created. The converter functions were all composed from these basic cells. This approach ensured an easy path from design into emulation.

The solution was made parameterizable to handle varying needs for accuracy.  Single bit inputs need to be translated into transitions at offset zero or a high or low coding depending on the previous state.  Single bit outputs deliver the final state of the high-resolution output either at time zero, the next falling, or the next rising edge of the grid clock, selectable by parameter. Output transitions can optionally be filtered to conform to a configurable minimum pulse width.

Timed Cell Structure

There are four critical elements to the design of the conversion function blocks (time cells):

                Input conditioning – convert to zero-offset, optional glitch preservation, and multi-cycle path

                Transition sorting – sort transitions according to timing offset and specified precedence

                Function – for each input transition, create appropriate output transition

                Output filtering – Capability to optionally remove multiple transitions, zero-width, pulses, etc.

Timed Cell Caveat

All of the cells are combinational and deliver a result in the same cycle of an input transition. This holds for storage elements as well. For example a DFF will have a feedback to hold its state. Because feedback creates combinational loops, the loops need a designation to be broken (using a brk input conditioning function in this case – more on this later). This creates an additional requirement for flip-flop clock signals to be restricted to two edges per reference clock cycle.

Note that without minimum width filtering, the number of output transitions of logic gates is the sum of all input transitions (potentially lots of switching activity). Also note that the delay cell has the effect of doubling the number of output transitions per input transition.

Figure 3: Edge doubling will increase switching during execution

SimVision Debug Support

The debug process was set up to revolve around VCD file processing and directed and viewed within the SimVision debug tool. In order to understand what is going on from a functional standpoint, the raw simulation output processes the encoded signals so that they appear as high-precision timing signals in the waveform viewer. The flow is shown in the figure below.

Figure 4: Waveform post-processing flow

The result is the flow is a functional debug view that includes association across representations of the design and testbench, including those high-precision timing signals.

Figure 5: Simvision debug window setup

Overview of the Design Under Verification (DUV)

Verification has to prove that analog design works correctly together with the digital part. The critical elements to verify include:

• Programmable delay lines move data edges with sub-ps resolution

• PLL generates clocks with wide range of programmable frequency

• High-speed data stream at output of analog is correct

These goals can be achieved only if parts of the analog design are represented with fine resolution timing.

Figure 6: Mixed-signal design partitioning for verification

How to Get to a Verilog Model of the Analog Design

There was an existing Verilog cell library with basic building blocks that included:

- Gates, flip-flops, muxes, latches

- Behavioral models of programmable delay elements, PLL, loop filter, phase detector

With a traditional simulation approach, a cell-based netlist of the analog schematic is created. This netlist is integrated with the Verilog description of the digital design and can be simulated with a normal workstation. To use Palladium simulation, the (non-synthesizable) portions of the analog design that require fine resolution timing have to be replaced by digital timing representation. This modeling task is completed by using a combination of the existing Verilog cell library and the newly developed timed cells.

Loop Breaking

One of the chief characteristics of the timed cells is that they contain only combinational cells that propagate logic from inputs to outputs. Any feedback from a cell’s transitive fanout back to an input creates a combinational loop that must be broken to reach a steady state. Although the Palladium XP loop breaking algorithm works correctly, the timed cells provided a unique challenge that led to unpredictable results.  Thus, a process was developed to ensure predictable loop breaking behavior. The user input to the process was to provide a property at the loop origin that the netlister recognized and translated to the appropriate loop breaking directives.

Augmented Netlisting

Ease of use and flow automation were two primary considerations in creating a solution that could be deployed more broadly. That made creating a one-step netlisting process a high-value item. The signal point annotation and automatic hierarchy expansion of the “digital timing” parameter helped achieve that goal. The netlister was enriched to identify the key schematic annotations at any point in the hierarchy, including bit and bus signals.

Consistency checking and annotation reporting created a log useful in debugging and evolving the solution.

Wrapper Cell Modeling and Verification

The netlister generates a list of schematic instances at the designated “netlister stop level” for each instance the requires a Verilog model with fine resolution timing. For the design in this paper there were 160 such instances.

The library of timed cells was created; these cells were actually “wrapper” cells comprised of the primitives for timed cell modeling described above. A new verification flow was created that used the behavior of the primitive cells as a reference for the expected behavior of the composed cells. The testing of the composed cells included had the timing width parameter set to 1 to enable direct comparison to the primitive cells. The Cadence Incisive Enterprise Simullator tool was successfully employed to perform assertion-based verification of the composed cells versus the existing primitive cells.

Mapping and Long Paths

Initial experiments showed that inclusion of the fine resolution timed cells into the digital emulation environment would about double the required capacity per run. As previously pointed out, the timed cells having only combinational forward paths creates a loop issue. This fact also had the result of creating some such paths that were more than 5,000 steps of logic. A timed cell optimization process helped to solve this problem. The basic idea was to break the path up by adding flip-flops in strategic locations to reduce combinational path length. The reason that this is important is that the maximum achievable emulation speed is related to combinational path length.

Results

Once the flow was in place, and some realistic test cases were run through it, some further performance tuning opportunities were discovered to additionally reduce runtimes (e.g., Palladium XP tbrun mode was used to gain speed). The reference used for overall speed gains on this solution was versus a purely software-based solution on the highest performance workstation available.

The findings of the performance comparison were startlingly good:

• On Palladium XP, the simulation speed is 50X faster than on Advantest’s fastest workstation

• Software simulation running 25 days can now be run in 12 hours -> realistic runtime enables long-running tests that were not feasible before

• Now have 500 tests that execute once in more than 48 hours

• They can be run much more frequently using randomization and this will increase test coverage dramatically

Steve Carlson

Verification is the top challenge in mixed-signal design. Bringing analog and digital domains together into unified verification planning, simulating, and debugging is a challenging task for rapidly increasing size and complexity of mixed-signal designs. To more completely verify functionality and performance of a mixed-signal SoC and its AMS IP blocks used to build it, verification teams use simulations at transistor, analog behavioral and real-number model (RNM) and RTL levels, and combination of these.

In recent years, RNM and simulation is being adopted for functional verification by many, due to advantages it offers including simpler modeling requirements and much faster simulation speed (compared to a traditional analog behavioral models like Verilog-A or VHDL-AMS). Verilog-AMS with its wreal continue to be popular choice. Standardization of real number extensions in SystemVerilog (SV) made SV-RNM an even more attractive choice for MS SoC verification.

Verilog-AMS/wreal is scalar real type. SV-RNM offers a powerful ability to define complex data types, providing a user-defined structure (record) to describe the net value. In a typical design, most analog nodes can be modeled using a single value for passing a voltage (or current) from one module to another. The ability to pass multiple values over a net can be very powerful when, for example, the impedance load impact on an analog signal needs to be modeled. Here is an example of a user-defined net (UDN) structure that holds voltage, current, and resistance values:

When there are multiple drives on a single net, the simulator will need a resolution function to determine the final net value. When the net is just defined as a single real value, common resolution functions such as min, max, average, and sum are built into the simulator.  But definition of more complex structures for the net also requires the user to provide appropriate resolution functions for them. Here is an example of a net with three drivers modeled using the above defined structural elements (a voltage source with series resistance, a resistive load, and a current source):

To properly solve for the resulting output voltage, the resolution function for this net needs to perform Norton conversion of the elements, sum their currents and conductances, and then calculate the resolved output voltage as the sum of currents divided by sum of conductances.

With some basic understanding of circuit theory, engineers can use SV-RNM UDN capability to model electrical behavior of many different circuits. While it is primarily defined to describe source/load impedance interactions, its use can be extended to include systems including capacitors, switching circuits, RC interconnect, charge pumps, power regulators, and others. Although this approach extends the scope of functional verification, it is not a replacement for transistor-level simulation when accuracy, performance verification, or silicon correlation are required:  It simply provides an efficient solution for discretely modeling small analog networks (one to several nodes).  Mixed-signal simulation with an analog solver is still the best solution when large nonlinear networks must be evaluated.

Cadence provides a tutorial on EEnet usage as well as the package (EEnet.pkg) with UDN definitions and resolution functions and modeling examples. To learn more, please login to your Cadence account to access the tutorial.

The IC6.1.8 ISR10 and ICADVM18.1 ISR10 production releases are now available for download.(read more)

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તો આજે આપણે જોઇએ કે કઇ રાશિનાં જાતકો માટે આ વૅલેન્ટાઇન કેવો રહેશે. તમને પ્રેમનો રંગ મળશે કે પ્રેમ પર પાણી ફરશે.

14 ફેબ્રુઆરીને વેલેન્ટાઈન ડે તરીકે ઉજવવામાં આવે છે. યુવાન હૈયાઓ આ દિવસની આતુરતાથી રાહ જોતા હોય છે. આ દિવસે યુવક યુવતીઓ પોતાના પ્રીય પાત્રને ગીફ્ટ આપીને પ્રેમનો એકરાર કરતા હોય છે. પરંતુ ગિફ્ટ આપવી અથવા લેવી અલગ અલગ ગ્રહો ઉપર અલગ અલગ અસર કરે છે.

આજના રાશીફળ પ્રમાણે જાણો તમારા ભાગ્ય, સ્વાસ્થ્ય, ધન, પ્રેમ-વિવાહ, નોકરી વગેરેની ભવિષ્યવાણી

વાસ્તુ શાસ્ત્ર પ્રમાણે ઘરમાં ધન સાથે સંકળાયેલી સમસ્યાઓને દૂર કરવા માટે કેટલાક નિયમો છે. આ નિયમોને અપનાવીને ઘરમાં પૈસાની પરેશાની રહેતી નથી.

વાસ્તુ શાસ્ત્ર પ્રમાણે તમારા ઘરમાં વાસ્તુના યોગ્ય નિયમોનું પાલન ન થાય તો ઘરમાં સકારાત્મક ઉર્જાની જગ્યાએ નકારાત્મક ઉર્જા વધારે થઈ જાય છે.

વાસ્તુશાસ્ત્રમાં અગ્ની દિશાનો વિશે, દોષ માનવામાં આવે છે. અગ્ની દેશમાં દોષ હોવાથી વ્યક્તિને અનેક પ્રકારની સમસ્યાનો સામનો કરવો પડે છે. વાસ્તુના જાણકાર પ્રમાણે અગ્ની ખૂામાં દોષને ખતમ કરવા માટે આ દિશમાં લાલ રંગનો એક બલ્બ અથવા તો દીવો એક પહોર અથવા આશરે ત્રણ કલાક સુધી ચાલે.

આ કાર્યક્રમમાં પુરુષો ઓછામાં ઓછા કપડામાં આવે છે, મોટાભાગના પુરુષો જાપાની લંગોટમાં જોવા મળ્યા

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