A feeding apparatus feeds a metal strip with cutaway portions in a conveying direction and includes: a reference plate on which the metal strip is placed and in which a slit is formed; moving bodies that are provided below the reference plate and are moved by driving means parallel to the reference plate in the conveying direction; feed pins that advance into the cutaway portions, are provided on the moving bodies so as to move up and down with respect to the reference plate, and pull the metal strip in the conveying direction when the moving bodies move; and at least one guide portion that contacts a side surface on an opposite side of the metal strip to the cutaway portions and guides conveyance of the metal strip.

A feeding and reversing mechanism for a strapping machine includes a forward-reverse wheel assembly and a tension wheel assembly which are mounted on a base and arranged in such a way to provide larger contact areas between a strapping band and the two wheel assemblies. The feeding and reversing mechanism further includes first and second spring units. The first spring unit helps to keep a suitable gap between an active wheel and a passive wheel of the tension wheel assembly for the strapping band to pass through. The second spring unit helps to move the passive wheel toward the active wheel of the tension wheel assembly, so that the strapping band can be clamped between the passive wheel and the active wheel tightly to facilitate reversing and tightening of the strapping band.

A method for regulating a web tension in a processing machine for processing a product web, in particular a shaftless printing press, includes separating a first product-web section from a second product-web section by a delay section. The web tensions in the first and second product-web sections are influenced by first and second actuators, respectively. To regulate the web tension in the first product-web section, the method further includes defining a regulation output value from which an actuating command for the first actuator is derived. An actuating command for the second actuator is defined from the regulation output value and a delay element to decouple the web tension in the second product-web section from the regulation of the web tension in the first product-web section. The delay element delays the effect of the regulation output value on the actuating command for the second actuator by a delay time.

A stock feeder for woodworking equipment includes a base, a cross clamp, a horizontal bar unit, a vertical bar unit, a feeding unit, and an electrical unit. The electrical unit has an electrical unit main body and a variable-frequency drive. The electrical unit main body has a first housing, a plurality of heat dissipation grooves provided on the outer periphery of the first housing, and a power fan which is independently mounted on a top portion of the first housing and in communication with the heat dissipation grooves. The variable-frequency drive has a second housing, a variable-frequency circuit sealed in the second housing, and a control panel exposed outside the second housing. The second housing has an outer surface provided with a plurality of heat dissipation slots corresponding in position to and in communication with the heat dissipation grooves of the electrical unit main body.

A tape feeder includes a guide part that guides a carrier tape and is detachably attached to a main body. The guide part includes: a lower member guiding the carrier tape and attached to and detached from the main body; an upper member pressing down the carrier tape from above; a tape introduction part guiding the carrier tape into the upper member at an upstream side thereof in a tape feed direction; a confirmation opening part disposed in the upper member for visually confirming that the carrier tape arrives at a pin engagement range; an open/close mechanism opening and closing the upper member with respect to the lower member; and a positioning mechanism fitting a positioning pin into a feed hole of the carrier tape in the guide part, thereby positioning the carrier tape relative to the guide part in the tape feed direction.

A vacuum roller for a web handling system comprises a hollow, cylindrical, rotably driven drum and an end cap threadingly mounted onto the rear end of the drum. Together, the drum and the end cap define a plurality of individual, externally communicable vacuum paths. A spherical, metal movable element is internally disposed within each vacuum path and regulates the passage of air therethrough. A plurality of magnetic elements is fixedly mounted on a stationary annular holder. In use, each magnetic element selectively displaces each movable element when disposed in close proximity thereto to the extent necessary so as to permit the passage of air through its corresponding vacuum path. As such, the vacuum roller is provided with a predefined range of suction, or vacuum zone, about the outer surface of its rotating drum that directly corresponds to the angular arrangement of the plurality of stationary magnetic elements.

To provide a wire unwinding auxiliary device capable of, compared to a conventional device, effectively preventing an unwound wire material from getting twisted, entangled or flawed. A wire unwinding auxiliary device used for guiding an unwound wire material when unwinding the wire material which is wound in a coiled shape. The device comprises a plurality of rotation members 1a-1e on which the unwound wire material is set to run therethrough, and a non-rotation member 2 provided adjacent to at least a rotation member 1a through which the wire material passes first in the plurality of rotation members 1a-1e, thereby a running path of the wire material is stabilized between the non-rotation member 2 and the rotation member 1a.

A printing device (100,101) has a first print engine (103, 303, 603, 703), a second print engine (105, 305, 605, 705), and a buffer device (107, 307, 609, 709, 711) disposed between the first (103, 303, 603, 703) and second print engines (105, 305, 605, 705). The buffer (107, 307, 609, 709, 711) is configured to store a variable amount of web substrate (106, 301, 713) received from the first print engine (103, 303, 603, 703) and feed the substrate (106, 301, 713) to the second print engine (105, 305, 605, 705).

A media diverter system for directing a media sheet traveling along an input media path into either a first media path or a second media path. One or more roller assemblies are provided including a media-guiding roller having one or more grooves formed around the exterior surface, and an air source for selectively providing an air flow into one or more of the grooves, the air flow being directed between the media sheet and the exterior surface of the media-guiding roller thereby producing a Bernoulli force to draw the media sheet toward the media-guiding roller. A controller selectively activates the air source in at least one of the roller assemblies while the corresponding media-guiding roller rotates around its roller axis to draw the media sheet toward the exterior surface of the media-guiding roller, thereby directing the media sheet into either the first media path or a second media path.

A web conveying apparatus that conveys a web, includes: a transverse position displacement detection unit that detects a transverse position displacement of the web; a transverse position correction unit that corrects a transverse position of the web by a guide roller; width detection units that detect a width size in a left-right direction of the web; and a control unit that controls the transverse position correction unit in accordance with the transverse position displacement detected by the transverse position displacement detection unit and performs feedback control to position the web in a target position. The control unit changes a correction amount in the feedback control in accordance with the width size of the web detected by the width detection units.

A tape feeder includes a guide part that guides a carrier tape and is detachably attached to a main body. The guide part includes: a lower member guiding the carrier tape and attached to and detached from the main body; an upper member pressing down the carrier tape from above; a tape introduction part guiding the carrier tape into the upper member at an upstream side thereof in a tape feed direction; a confirmation opening part disposed in the upper member for visually confirming that the carrier tape arrives at a pin engagement range; an open/close mechanism opening and closing the upper member with respect to the lower member; and a positioning mechanism fitting a positioning pin into a feed hole of the carrier tape in the guide part, thereby positioning the carrier tape relative to the guide part in the tape feed direction.

In a multiple endless belt type band sheet coiling tension applying apparatus in which a coiling tension is applied to slit band sheets a by a frictional force generated by slippage between belt pressing surfaces 4a, 5a and internal belt surfaces 1a of endless belts 1, a friction plate 8 made of a thin metallic sheet having heat conductivity equal to or better than that of the belt pressing units 4a, 5a is detachably installed on a front surface of each of the belt pressing units 4a, 5a.

A recording apparatus includes a recording section configured to jet a liquid, and a transport mechanism configured to transport a recording medium on which an image is recorded by the liquid jetted from the recording section. The transport mechanism includes a guide surface extending linearly and configured to guide one of two lateral ends of the recording medium transported, a driving roller configured to contact with one surface of the recording medium on a side with no image recorded and to transport the recording medium; and a driven spur having at least one spur configured to contact with the other surface of the recording medium on the side with the image recorded so as to nip the recording medium in cooperation with the driving roller, and to rotate along with the transport of the recording medium by the rotation of the driving roller.

There is provided a recording apparatus including a recording section and a transport mechanism, which has a guide surface, a driving roller, and a driven spur. A length X (mm) of a front end surface of the driven spur and an angle Y of the driven spur are configured to be within a first area surrounded by a mathematical expression 1 which is X>0, a mathematical expression 2 which is Y>0, a mathematical expression 3 which is Y=40.1X+1.6, a mathematical expression 4 which is Y=−9.0X+5.6, a mathematical expression 5 which is Y=−12.1X+6.0, and a mathematical expression 6 which is Y=−14.7X+7.1.

Provided is a web guiding apparatus capable of ensuring a smooth operation and durability against a force applied from a web even if the apparatus is used in an environment with airborne paper powder, dust and the like. The web guiding apparatus includes a rocking frame 4 rocking around an axis perpendicular to a reference surface 2s of the base 2, and a support portion 40 supporting movement of the rocking frame 4 with respect to the base 2. The support portion 40 includes a base member 41 provided on the base 2 and having a rolling surface parallel to the reference surface 2s of the base 2, and a roller 46 provided on the rocking frame 4 so as to roll on the rolling surface of the base member 41. The rolling surface of the base member 41 is formed so that an axial direction thereof intersects an arc with a rocking shaft 3 of the rocking frame 4 as a center. A width of the roller 46 is wider than a width of the rolling surface of the base member 41. The roller 46 is provided so as to move along the arc with the rocking shaft 3 of the rocking frame 4 as the center when the rocking frame 4 rocks.

A film transport apparatus includes: an edge sensor that detects a lateral position deviation of a film; a lateral position correction device that corrects a lateral position of the film with a guide roll; a tension sensor that detects tensions applied respectively near left and right ends of the film; and a control unit that executes feedback control such that the lateral position correction device is controlled on the basis of the lateral position deviation detected by the edge sensor so that the film is located at a target position. The control unit changes the feedback control based on a left and right tension difference, which is a difference between the tension applied near the left end of the film and the tension applied near the right end of the film, the tensions being detected by the tension sensor.

A printing apparatus includes: a motor which drives a shaft of a roll body around which a medium is wound, in the feeding direction of the medium; a transport roller which transports the medium fed from the roll body; and a control section which supplies electric power for rotating the roll body to the motor, wherein the electric power that the control section supplies to the motor at the time of the start of the feeding of the medium is larger when the diameter of the medium that is wound around the roll body is R2 (

A buffer store for a flat web material includes two roller registers having freely rotatable rollers movable relative to one another in a direction radial to a roller axis, thereby forming loops of the web material between the rollers, a piston-cylinder arrangement having a chamber containing a compressible medium and acting as a spring between the registers to generate web tension in the material, and a control-valve arrangement that switches between a first condition, for normal operation, and a second condition, for operation during a fault. In the first condition, the control-valve arrangement connects the cylinder chamber of the piston-cylinder arrangement to a device for providing a constant operating pressure. In the second condition, the control-valve arrangement closes the cylinder chamber of the piston-cylinder arrangement and connects it to a relief valve that relieves pressure therein to a residual pressure significantly smaller than the operating pressure.

A wire-processing machine or apparatus includes a wire-feeding apparatus for guiding a wire, wherein the wire-processing machine or apparatus contains a wire drive for forward movement of the wire and a guide pipe with an entry opening and an exit opening. The wire-processing machine or apparatus contains a swivel unit with drive and a wire-gripping apparatus which is arranged on a swivel arm, wherein an exit side end of the guide pipe is fastened to the swivel arm. The wire drive and the guide pipe are arranged in such manner that the wire can be shot-in through the guide pipe. The wire-feed apparatus further contains a length-compensating unit which is arranged in the area of the guide pipe and which, in a first state, shortens an effective length of the guide pipe and, in a second state, lengthens the effective length of the guide pipe.

An accumulating apparatus (4) has an upper arm (51) in which a plurality of upper rollers (511) are arranged, and a lower arm (52) in which a plurality of lower rollers (521) are arranged. An upper gear (61) is fixed to the upper arm and a lower gear (62) is fixed to the lower arm. The upper gear is engaged with the lower gear so that the upper arm and the lower arm are simultaneously moved in opposite directions with respect to a vertical direction. Therefore, when moving the lower arm in the vertical direction, influence of the weight of the lower arm is canceled by the weight of the upper arm, and a force to move the lower arm upward can be reduced. As the result, an air cylinder (63) for changing a distance between the upper arm and the lower arm can be downsized.

A dispenser for dispensing paper toweling. The dispenser including a towel support that is positionable in a first dispensing position when a drive roller rotates in a first direction, and that is positionable in a second auto-loading position when the drive roller rotates in a second direction. Rotation of the drive roller in the first and second directions automatically loading the paper toweling for subsequent dispense.

In the separation of a cover tape 15e from a carrier tape 15 performed by a cover tape separating mechanism 50, a cover tape 15e, which is separated from a base tape 15a by a separating blade edge 51f, comes into contact with a concave conical surface 52c, so that one side portion of a cover tape 15e is bent toward the other side portion; and the bent cover tape 15e is pressed against a guide surface 32s from below while the carrier tape 15 is guided to a pick-up position. Accordingly, the cover tape 15e is folded on the base tape 15a in a flat shape.

A debris sweep and dry assist device is for use with a strapping machine. The debris sweep and dry assist device is positioned between the strapping machine and an associated strap supply. The device includes a body having a strap inlet and a strap outlet and defining a strap path therethrough. The body has a first wall at about the strap inlet and a second wall at about the strap outlet. The body has a first manifold and a plurality of first branches extending between the first manifold and the first wall to provide a plurality of flow paths from the first manifold to the environs through the first branches. A compressed is gas directed into the first manifold and flows out of the first branches, and is directed onto strap material at a location at about the strap inlet.

A sheet conveyance apparatus includes a conveyance roller pair that has a roller with a uniform diameter in a sheet width direction and that is configured to pinch and convey a sheet, and a guide unit that is provided on an upstream side of the conveyance roller pair and that is configured to regulate a position of an edge of the sheet, wherein the conveyance roller pair conveys the sheet in a state in which the sheet is bended by the guide unit so that on a roller side with a uniform diameter in a sheet width direction, the sheet convexly bends.

A method is disclosed for web tension setting in a processing machine for processing a material web, in particular a shaftless printing press. In order to set the web tension in a first web tension section with a length L which is delimited upstream by a first clamping point and downstream by a second clamping point, the first clamping point is loaded with a first manipulated variable which is produced using a first element with a first transfer function G1(s) (G3), and the second clamping point is loaded with a second manipulated variable which is produced using a second element with a second transfer function G2(s) (G4), wherein c1G1(s)=−c2G2(s). Thus, it is possible to keep the speed constant even during the regulation at a fixed or variable point x within the web tension section, wherein x=|c1/(c1+c2)|L lies behind the first clamping point.

The device (100) is destined to receive flanked continuous strips (1, 2) from an arrival line (L), and feed them towards a transversal cutting station (SR). The device (100) comprises: a basin (3), associated to a terminal part of the arrival line (L), destined to enable formation, in each of the strips (1, 2) of a free loop (A1, A2) in a downwards direction; deviator organs (4), at a 45° angle, provided downstream of the basin (3), destined to guide the strips (1, 2) such as to orientate them perpendicularly to the arrival direction, horizontally centered and correctly staggered in height such as to enter the transversal cutting station (SR).

According to one embodiment, a tractor comprises a guide shaft, a first belt unit, a second belt unit, a fixing unit and a connecting unit. The first belt unit is supported by the guide shaft so as to move in an axis direction of the guide shaft. The second belt unit is arranged to face the first belt unit in the axis direction of the guide shaft and supported by the guide shaft. The fixing unit, which is movably supported by the guide shaft in the axis direction of the guide shaft and is capable of being fixed on the guide shaft. The connecting unit configured to connect the first belt unit to the fixing unit with a clearance in the axis direction of the guide shaft.

A flexible and continuous substrates-conveying sheet has a plurality of to be processed substrates disposed on or in it. A nondestructive transferring unit includes a plurality of first transferring rolls and a plurality of second transferring rolls. The first transferring rolls make contact with a first surface of the substrates-conveying sheet where that surface can have electrostatically-induced charge formed thereon. Each of the first transferring rolls includes a first central portion charged with a positive electric charge and a first outer portion surrounding the first central portion. The second transferring rolls make contact with the first surface of the substrates-conveying sheet. The second transferring rolls are disposed alternately with the first transferring rolls. Each of the second transferring rolls includes a second central portion charged with a negative electric charge and a second outer portion surrounding the second central portion.

In a web printer, tension on the moving web is controlled by monitoring the tension on the web between two rollers and selectively operating an actuator driving the second roller to restore the tension to an acceptable range. The operation of the actuator includes modulating the speed at which the second roller is driven.

A web tensioner, a web slitter, a method of tensioning a web, and a method of slitting a web are provided. A corrugated edge nip is used in the tensioner, the slitter, and the methods of tensioning and slitting. The corrugated edge nip can provide a crossweb tension to a suspended web or film in a web line. The corrugated edge nip can be used in conjunction with, for example, a rotary shear slitter to improve slit edge quality.

Groups of phase shifted Pulse Width Modulation signals are generated that maintain their duty-cycle and phase relationships as a function of the period of the PWM signal frequency. The multiphase PWM signals are generated in a ratio-metric fashion so as to greatly simplify and reduce the computational workload for a processor used in a PWM system. The groups of phase shifted PWM signals may also be synchronized with and automatically scaled to match external synchronization signals.

A device for detecting a PWM wave, comprising: a PWM wave generating module, configured to generate the PWM wave; a detecting module coupled to the PWM wave generating module, configured to receive the PWM wave and to determine an electric level of the PWM wave; a timer coupled to the detecting module, configured to start a counting when the detecting module receives the PWM wave, and to interrupt the counting when the counting reaches a predetermined value, the detecting module determining whether the electric level of the PWM wave is a high electric level or a low electric level when the counting is interrupted; and a calculating module coupled to the detecting module, configured to calculate a duty ratio of the PWM wave based on a number of high electric level and a number of low electric level of the PWM wave determined within one period of the PWM wave.

In an embodiment, a method of generating a pulse-width modulated signal from an input signal includes calculating a finite number of basis functions of a first pulse-width modulated signal based on the input signal, and forming an electronic output based on the calculated finite number of basis functions.

A phase-locked loop double-point modulator may include a frequency divider having a ratio which can be changed by a first modulation signal, and an oscillator, a frequency of which can be changed by a second modulation signal correlated to the first modulation signal. A calibration circuit may be configured, in a calibration mode, to match the gains of the first and second modulation signals based on frequency measurements of the oscillator for two different calibration values of the second modulation signal. The phase-locked double-point modulator may also include an attenuator having a constant ratio greater than 1 and placed in the path of the second modulation signal, and a selector switch configured to be controlled by the calibration circuit to reduce the ratio of the attenuator in the calibration mode.

An amplifier receives an amplitude signal of a polar modulated signal at a base terminal of a transistor and receives a phase modulated carrier signal of the polar modulated signal at the base terminal of the transistor. The amplifier combines the amplitude signal and the phase modulated signal to produce a full complex waveform at a collector terminal of the transistor.

Some embodiments relate to a phase shifter that includes an I/Q phase shifter and at least one LC balun. Compared to conventional phase shifters, phase shifter has primarily only LC components, thereby limiting losses relative to conventional solutions. In one embodiment, for example, a phase shifter shows a large bandwidth at 77 GHz center frequency (e.g., 1 dB amplitude error bandwidth is approximately 40 GHz; 1° phase error bandwidth is about 16.5 GHz). The inductors included in phase shifter, in contrast to the quarter wave transmission lines used in conventional phase shifters, reduces chip area compared with conventional solutions. In some embodiments, an emitter follower helps to provide a relatively constant output that is largely independent of temperature, input power, VCC, manufacturing variation, and so on.

A frequency synthesizer for a WLAN transceiver is disclosed that may be used to generate 5.4 GHz and 2.4 GHz signals. The frequency synthesizer may be configured to minimize VCO pulling by using VCO operating frequencies that are not integer multiples of the RF bands. Further, the frequency synthesizer may be configured to minimize interference with other frequency bands used by existing wireless systems.

A modulator generates a baseband digital signal from an information-bearing digital signal. The baseband signal has time-varying phase and amplitude defined by a sequence of complex data words, each having an in-phase (I) component and a quadrature (Q) component. A noise-shaping modulator generates a noise-shaped digital signal from the baseband digital signal such that quantization noise in the noise-shaping modulator is attenuated by a spectral null of its noise transfer function. The spectral null is selected by a noise-shaping parameter corresponding to a selected one of a plurality of output frequencies. A signal converter generates an analog signal conveying the information of the information-bearing digital signal on an analog carrier signal having the selected output frequency.

A signal generator for a transmitter or a receiver for transmitting or receiving RF-signals according to a given communication protocol includes an oscillator and a mismatch compensator. The oscillator is configured to provide a signal generator output signal having a signal generator output frequency and comprises a fine tuning circuit for providing a fine adjustment of the signal generator output frequency based on a fine tuning signal and a coarse tuning circuit for providing a course adjustment of the signal generator output frequency based on a coarse tuning signal. The mismatch compensator is configured to receive the signal generator output signal and compensate a frequency mismatch between a desired signal generator output frequency and the signal generator output frequency generated by the oscillator by providing the fine tuning signal for changing the state of the fine tuning circuit of the oscillator and by providing the coarse tuning signal for changing a state of the coarse tuning circuit of the oscillator. The mismatch compensator provides the coarse tuning signal during a guard period defined in the given communication protocol, during which no RF-signals are transmitted by the transmitter or no RF-signals are to be received by the receiver, such that the state of the coarse tuning circuit is changed within the guard period.

Parallel/serial conversion is performed on an N (where N is a natural number)-bit first parallel data signal with a first converted clock acquired by multiplying a reference clock by N, and parallel/serial conversion is performed on an (N×K)-bit (where K is a natural number) second parallel data signal with a second converted clock acquired by multiplying the reference clock by N×K.

A method for tuning a digital compensation filter within a transmitter includes: obtaining at least one resistance-capacitance (RC) detection result, wherein the digital compensation filter includes an RC compensation module; and tuning the digital compensation filter by inputting the RC detection result into the RC compensation module. For example, the RC detection result may correspond to a detected value representing a product of a resistance value and a capacitance value. In another example, the at least one RC detection result may be obtained by performing RC detection on at least a portion of the transmitter without individually measuring resistance values of resistors therein and capacitance values of capacitors therein. An associated digital compensation filter and an associated calibration circuit are also provided.

A new coded continuous phase modulation (CPM) scheme is proposed to enhance physical layer performance of the current DVB-RCS standard for a satellite communication system. The proposed CPM scheme uses a phase pulse design and combination of modulation parameters to shape the power spectrum of CPM signal in order to improve resilience to adjacent channel interference (ACI). Additionally, it uses a low complexity binary convolutional codes and S-random bit interleaving. Phase response using the proposed CPM scheme is a weighted average of the conventional rectangular and raised-cosine responses and provides optimum response to minimize frame error rate for a given data rate.

A PWM circuit that can have two refresh rates, including: a first PWM signal generator and a second PWM signal generator; wherein the first PWM signal generator and the second PWM signal generator respectively control refresh rates in two dimensions of an output data generated from a target apparatus. A PWM signal generation method that can have two refresh rates, including: generating a first PWM signal; generating a second PWM signal; and controlling refresh rates in different dimensions of an output data generated from a target apparatus respectively by using the first PWM signal and the second PWM signal.

A digital pulse width modulation controller includes a pulse width modulation controller, a selection unit having at least one selector, a comparison unit having at least one comparator, and a signal conversion unit having at least one digital-to-analog converter. The digital-to-analog converter generates a reference current and/or voltage. The comparator receives the reference current and/or voltage, and performs a comparison operation to generate a comparison signal based on a feedback signal. The selector selects one selection signal to input into the pulse width modulation controller, which receives other parameters set by a user or the system at the same time so as to control characteristics of the digital pulse width modulation signals, thereby improving the electric properties of a loading circuit.

Techniques and mechanisms for configuring logic to implement a signal modulation. In an embodiment, the logic includes a finite impulse response (FIR) module comprising circuitry. The selection circuitry may be operable to concurrently receive signals from latch circuitry of the FIR module and, based on the signals, to select an input group of the selection circuitry and to output a voltage identifier. In another embodiment, configuration logic is operable to set an operational mode which determines a total number of concurrent input signals, received by the FIR module, which the FIR module will use to select an input group for generating an output representing a voltage level.

A circuit includes a switched modulator stage combining an information signal with a square wave carrier to produce a first modulated signal; and a second modulation stage forming additional steps in the first modulated signal to produce a second modulated signal.

A rail-to-rail comparator including a first comparison unit connected to a first terminal and configured to compare differential input signals to differential reference voltages; a second comparison unit connected to a second terminal and configured to compare the differential input signals to the differential reference voltages; and an output unit configured to be driven in response to a clock signal and to generate a complementary output signal according to comparison results of the first and second comparison units.

An irrigation control device having a modulator that modulates data onto an alternating power signal by distorting amplitude of a first leading portion of selected cycles of the alternating power signal, and permit effectively a full amplitude of the alternating power signal on a following portion of the selected cycles, wherein the first leading portion and the following portion are either both on a high side of a cycle or both on a low side of a cycle of the alternating power signal. The irrigation control device further includes an interface configured to couple the modulator to a multi-wire interface coupled to a plurality of irrigation devices to permit the alternating power signal to be applied to the multi-wire interface.

An example PWM includes a driver and a two-way oscillator. The oscillator includes, a first frequency adjust current source, a second frequency adjust current source, a capacitor, a switching reference and a comparator. The capacitor integrates a frequency adjust current by charging with the first frequency adjust current source. The capacitor subsequently integrates a second frequency adjust current by discharging with the second frequency adjust current source. The switching reference outputs a first reference voltage and a second reference voltage responsive to an oscillator signal. The comparator compares the output of the switching reference with a voltage on the capacitor. The first and second frequency adjust current sources vary the first and second frequency adjust currents to vary the frequency of the PWM signal to spread energy of switching harmonics over a frequency band and to reduce EMI.

A time-varying formant is generated at a formant frequency by generating first and second harmonic phase signals having first and second harmonic numbers, respectively, in relation to a modulation frequency. The first and second harmonic phase signals are generated in proportion to a master phase signal, which varies at the modulation frequency, modulo a factor corresponding to their harmonic numbers. First and second sound signals, based on the first and second harmonic phase signals, are frequency modulated to create an arbitrarily rich harmonic spectrum, depending on an FM index. The time-varying formant is generated by generating a time-varying combination of the first and second harmonic sound signals, weighting the first and second harmonic sound signals in accordance with their spectral proximities to the formant frequency. One or more of the harmonic numbers are updated when the time-varying formant frequency passes the frequency of either sound signal.