Abstract: To facilitate measurement of the jitter tolerance of circuitry such as serializer/deserializer (SERDES) circuitry, test circuitry is provided that can add jitter to a data signal. The jitter added is preferably controllable and variable with respect to such parameters as jitter frequency (i.e., how rapid is the jitter) and/or amplitude (i.e., how large or great is the amount of the jitter).

Abstract: A PWM controller that effectively transitions between normal mode and green power mode is disclosed. A driver provides a normal drive signal during normal operation. A pulse width detector detects the pulse width of the PWM signal and if the pulse width drops below a threshold the normal mode drive signal will be turned off and a pulse ON time measurer will begin storing the pulse ON time. When the total ON time reaches a total ON time threshold or the output voltage drops below a voltage limit, a green mode drive signal will be output to the power converter. During green mode the driver will continue sending the green mode drive signal at intervals until a heavy load condition when the green mode drive signal will be shut off and the driver will resume sending the normal mode drive signal.

Abstract: A duty cycle stabilizer circuit (50) receiving an input clock signal and generating an output clock signal having a first duty cycle includes a leading edge pulse generator (52) and a pulse width extender circuit (54). The pulse generator generates a first clock pulse (V1) having a leading edge triggered by the leading edge of the input clock signal and a first pulse width. The pulse width extender circuit generates a second clock pulse (V2) having a leading edge triggered by the leading edge of the first clock pulse and a pulse width being stretched to the desired duty cycle. The duty cycle stabilizer further includes a buffer (64) providing the output clock signal having the first duty cycle, a charge pump (56) receiving the output clock signal directly and a differential amplifier (62) generating an output signal for controlling the pulse width of the first and second clock pulses.

Abstract: Systems and methods for pulse width modulating waveforms to represent asymmetric signal levels using pulses that are symmetric within their respective switching periods. One embodiment comprises a pulse width modulation system including an asymmetric correction unit and a pair of modulators. The asymmetric correction unit receives samples of an input signal and produces two separate output signals for corresponding modulators. For each sample, the asymmetric correction unit determines whether the signal level of the sample is symmetric or asymmetric. If the signal level of the sample is symmetric, the sample is forwarded to each of the modulators. If the signal level is asymmetric, the asymmetric correction unit increases one modified sample to the next higher symmetric signal level and decreases another modified sample to the next lower symmetric signal level and forwards the modified samples to the modulators.

Abstract: A circuit for controlling a duty cycle of a clock signal. The circuit includes a duty cycle control loop that includes a voltage-to-duty cycle (V-to-DC) converter, an output driver, a duty-cycle-to voltage (DC-to-V) converter, and an operational amplifier. The V-to-DC converter receives an input clock signal. The output driver is coupled to the V-to-DC converter and provides an output clock signal that is associated with a duty cycle distortion value. The DC-to-V converter converts the output clock signal to an average voltage. The operational amplifier amplifies an error between the average voltage and a reference voltage. The error is fed back to the V-to-DC converter through a negative feedback loop, wherein the V-to-DC converter adjusts a duty cycle of the input clock signal based on the error.

Abstract: A system and method for generating a correction signal for correcting duty cycle error of a first clock signal relative to a second complementary clock signal. Changes to a time difference between high- and low-portions of the first clock signal are detected and the correction signal is generated in response to and accordance with the detected changes.

Abstract: The present invention relates to a duty correction circuit that corrects a distorted duty of a clock signal using a delay unit and a delay controller, thereby reducing the layout area and current consumption.

Abstract: A pulse extension circuit for extending a pulse signal includes an input unit for receiving the pulse signal, an edge detection unit coupled to the input unit for generating a initiation signal, a pulse initiation unit coupled to the edge detection unit for outputting a control signal and adjusting a voltage level of the control signal, a pulse width control unit coupled to the pulse initiation unit for outputting a termination signal, a reset unit coupled to the edge detection unit, the pulse initiation unit and the pulse width control unit for outputting the first reset signal and the second reset signal to reset the pulse initiation unit and the pulse width control unit, and an output unit coupled to the input unit and the pulse initiation unit for extending a signal period of the pulse signal according to the pulse signal and the control signal.

Abstract: A clock duty cycle correction (DCC) circuit for correcting a clock duty cycle of an external clock includes a phase comparator for comparing a phase of a rising clock with that of a falling clock to thereby output comparing signal; a DCC controller for outputting a DCC enable signal and a weight selection signal in response to the comparing signal and a first and a second lock state signal; a DCC mixing block for blending the rising clock and the falling clock in response to the DCC enable signal and the weight selection signal to thereby generate a rising and a falling pre-clock signals; and a clock selector for selectively output the rising and the falling pre-clock signals in response to the weight selection signal.

Abstract: A duty detection circuit is provided with a main circuit unit that includes at least a first capacitor that is discharged during the time period in which the clock signal is at a high level and charged during the time period in which the clock signal is at a low level, and a second capacitor that is charged during the time period in which the clock signal is at a high level and discharged during the time period in which the clock signal is at a low level, with the main circuit unit alternately charging or discharging the first and second capacitors in synchrony with the clock signal; and a duty correction signal generator for detecting the potential difference of the first and second capacitors and outputting a duty correction signal based on the potential difference.

Abstract: A Duty Cycle Correction (DCC) circuit is provide in which pairs of field effect transistors (FETs) in known DCC circuit topologies are replaced with linear resistors coupled to switches of the DCC circuit such that when the switch is open, the input signal is routed through the linear resistors. The linear resistors are more tolerant of process, voltage and temperature (PVT) fluctuations than FETs and thus, the resulting DCC circuit provides a relatively smaller change in DCC correction range with PVT fluctuations than the known DCC circuit topology that employs FETs. The linear resistors may be provided in parallel with the switches and in series with a pair of FETs having relatively large resistance values. The linear resistors provide resistance that pulls-up or pulls-down the pulse width of the input signal so as to provide correction to the duty cycle of the input signal.

Abstract: A duty detection circuit includes an integration circuit for receiving an RCLK signal and an FCLK signal that are internal clock signals generated by a DLL circuit, and generating voltage levels in accordance with the duty ratio of these internal clock signals; an amplifier for amplifying the output of the integration circuit; a latch circuit for latching the output of the amplifier; a control circuit for controlling the operation timings of each component; a bias circuit for feeding a BIAS signal to the integration circuit; and a frequency monitor circuit unit for monitoring the frequency of the clock signal. The frequency monitor circuit unit is a circuit component used when the power source is turned on, during resetting, and when other initial settings are performed, and detects the actual frequency of the clock signal and adjusts the amount of charging or discharging of the capacitors C1 through C4 in the integration circuit according to this actual frequency.

Abstract: A converter circuit and method for converting a pulse-width modulated input signal into a voltage output signal eliminates an offset due to component mismatch. The converter circuit includes at least two channels. Each channel has an operational amplifier with differential inputs and differential outputs. A first capacitor in each channel provides a negative feedback from a first output to a first input and a second capacitor in each channel provides a negative feedback from a second output to a second input. Each channel is conditioned by a switch array in response to the pulse-width modulated signal to operate in a selected one of an integration mode, a sampling mode and a reset mode. In each channel, in the integration mode, the switch array selectively connects the reference current source of first polarity either to the first or to the second input of the operational amplifier, and the reference current source of second polarity to the other of the first and second inputs.

Abstract: A pulse width modulation circuit 1 of the present invention changes the voltage of a first integration circuit C1 during the first period T1 of the clock signal MCLK based on a current based on an audio signal eS, changes the voltage of the first integration circuit C1 based on a constant bias current in the opposite direction while changing the voltage of a second integration circuit C2 during the second period T2, and changes the voltage of the second integration circuit C2 based on the bias current during the third period T3. The amount of time from the start of the second period T2 until the voltage of the first integration circuit C1 reaches the reference voltage Vth is detected, and the amount of time from the start of the third period T3 until the voltage of the second integration circuit C2 reaches the reference voltage Vth is detected.

Abstract: A duty cycle detector including a first circuit, a second circuit, and a third circuit. The first circuit is configured to receive a clock signal having a first duty cycle and to provide a first oscillating signal having a first period proportional to the first duty cycle. The second circuit is configured to receive an inverted clock signal that is the inverse of the clock signal and having a second duty cycle and to provide a second oscillating signal having a second period proportional to the second duty cycle. The third circuit is configured to provide first output signals that indicate the first duty cycle of the clock signal based on a first phase difference between the first oscillating signal and the second oscillating signal.

Abstract: There is a provided a dual mode clock generator that is applicable to a direct current-direct current converter of a power supply. The dual mode clock generator includes a frequency controller for controlling generation of charge and discharge; a current source unit for generating a charge, and generating a charge; a capacitor for charging a voltage according to the charge current generated by the current source unit; an oscillation controller for controlling switch-on or switch-off to charge and discharge the capacitor; a switch for controlling the charging and discharging of the capacitor through the ON or OFF control of the oscillation controller; and a current sink unit for generating a discharge current according to the second current in the first operation mode and generating a discharge current according to the third current and the fourth current in the second operation mode.

Abstract: A digital-to-analog converter adapted for use as a feedback converter in a continuous time sigma delta analog-to-digital converter. The digital-to-analog converter has a discrete time digital signal input accepting digital signal samples that are synchronized with an assertion of a first data clock signal and a discrete time clock generator that generates an output pulse in response to receiving an assertion of the first data clock. The output pulse is asserted for a fixed duration that is independent of a jitter of the first data clock. The digital-to-analog converter also includes a continuous time analog output that produces, during assertion of the output pulse, a continuous time analog output signal having a magnitude corresponding to the digital signal samples.

Abstract: A high frequency delay circuit operable to output a high frequency signal delayed for a desired delay time. The high frequency delay circuit includes: a variable delay circuit operable to receive a reference signal of which a frequency is lower than the high frequency signal, and to output a delay reference signal delayed from the reference signal for the desired delay time in advance; and a multiplier operable to generate the high frequency signal, of which a frequency is a frequency of the delay reference signal multiplied by a predetermined value, and to output the generated high frequency signal at timing according to a phase of the delay reference signal.

Abstract: A method for synchronizing a plurality of programmable timing verniers with a reference pulse signal, each of the verniers being programmable to one of a plurality of timing steps within a delay range determined by a control signal applied to a bias input. A first and second control vernier is selected from the plurality of verniers, the first control vernier is programmed to a first delay, and the second control vernier is programmed to a second delay. The first and second control verniers are triggered together to generate respective first and second delay signals. A difference pulse signal is generated with a duty cycle corresponding to a difference between the generated first delay signal and second delay signal. The duty cycle of the pulse signal is compared to a duty cycle of the reference pulse signal to generate a difference signal pulse.

Abstract: Embodiments of a signal generating circuit are generally described herein. Other embodiments may be described and claimed.

Abstract: A sampling clock signal controller for receivers of digital data is disclosed. Specific bit patterns of a data waveform can be identified, and stored time samples of the waveform that correspond to the specific bit patterns can be analyzed to improve the timing of a sampling clock signal. These “time-amplitude” samples on known bit patterns can be utilized to determine if a sample on the data waveform should be taken before the center of the eye pattern, at the center of the eye pattern, or after the center of the eye pattern and by what time change. Accordingly, a single low power clock can be utilized to adjust the timing of the sample clock such that improved communication scan be achieved. Such a single clock system has reduced power requirements and increased accuracy.

Abstract: An apparatus for extracting a maximum pulse width of a pulse width limiter is provided. The apparatus performs such extraction using a circuit that is configured to eliminate a majority of delay cells. The elimination of delay cells is made possible by replacing an OR gate in the circuit configuration with an edge triggered re-settable latch. The replacement of the OR gate with the edge triggered re-settable latch reduces the amount of chip area used in addition to the power consumption of the circuit.

Abstract: A cycle modulation circuit capable of limiting peak voltage to provide a pulse width control signal to a rear end power driving unit includes a comparison unit, an input voltage source and a linear voltage generation unit. The comparison unit compares an oscillation waveform signal generated by the linear voltage generation unit against a base value of a waveform signal level generated by the input voltage source to modulate and output the pulse width control signal of a combined cycle consisting of a high level and a low level. The pulse width control signal is input to the rear end power driving unit to limit the power driving unit in an equal restricted voltage peak value zone and determine the allowable duty cycle according to the level waveform signal.

Abstract: A pulse width modulation (PWM) generating circuit includes a first comparator, a first resistor, a second resistor, a third resistor, a fourth resistor, a capacitor, and a diode. The first resistor and the second resistor are connected in series between a voltage input and ground. The third resistor, the fourth resistor, and the capacitor are connected in series between the voltage input and ground. The first comparator has a non-inverting input connected to a node between the first resistor and the second resistor, an inverting input connected to a node between the fourth resistor and the capacitor, and an output connected to a node between the third resistor and the fourth resistor. The diode is connected between the non-inverting input and the output. The inverting input of the first comparator provides triangular wave signals to a second comparator by which PWM signals are generated.

Abstract: A semiconductor memory device includes: a memory cell array, in which electrically rewritable and non-volatile memory cells are arranged; a sense amplifier circuit configured to be coupled to the memory cell array; a data transfer circuit disposed between the sense amplifier circuit and data input/output ports; a control signal generation circuit configured to generate a plurality of control signals based on a reference clock signal externally supplied, the control signals serving for controlling data input and output of the sense amplifier circuit and data transferring timing in the data transfer circuit; and an internal clock signal generation circuit configured to generate an internal clock signal based on the reference clock signal for serving as the basis of the control signals, the internal clock signal having the same clock cycle as the reference clock signal and a constant duty ratio without regard to the duty ratio of the reference clock signal.

Abstract: A clock duty cycle correction (DCC) circuit for correcting a clock duty cycle of an external clock includes a phase comparator for comparing a phase of a rising clock with that of a falling clock to thereby output comparing signal; a DCC controller for outputting a DCC enable signal and a weight selection signal in response to the comparing signal and a first and a second lock state signal; a DCC mixing block for blending the rising clock and the falling clock in response to the DCC enable signal and the weight selection signal to thereby generate a rising and a falling pre-clock signals; and a clock selector for selectively output the rising and the falling pre-clock signals in response to the weight selection signal.

Abstract: In an exemplary embodiment of the present invention, a local clock buffer (LCB) fabricated in a semiconductor receives a global clock signal as input. The LCB implements a pulse width controller that is operationally coupled to the LCB and an output driver forming a ring oscillator. The output driver outputs a pulse width adjusted signal. The pulse width of the pulse width adjusted signal is adjustable by way of the pulse width controller and is related in frequency to the global clock signal. A second ring oscillator (also referred to as the nclk loop) can also be implemented to server as the global clock signal. The pulse width controller can be used to precisely adjust the pulse width of the pulse width adjusted signal. A pulse width multiplier can be implemented to allow direct observation and measurement of the pulse width of the pulse width adjusted signal.

Abstract: A PWM controller that effectively transitions between normal mode and green power mode is disclosed. A driver provides a normal drive signal during normal operation. A pulse width detector detects the pulse width of the PWM signal and if the pulse width drops below a threshold the normal mode drive signal will be turned off and a pulse ON time measurer will begin storing the pulse ON time. When the total ON time reaches a total ON time threshold or the output voltage drops below a voltage limit, a green mode drive signal will be output to the power converter. During green mode the driver will continue sending the green mode drive signal at intervals until a heavy load condition when the green mode drive signal will be shut off and the driver will resume sending the normal mode drive signal.

Abstract: A method and a circuit for extracting current-voltage characteristics employ two pulse signals with different duty cycles into a device to be measured in order to extracting current-voltage characteristics of the device to be measured. The present invention may reduce the self-heating effect of the device to be measured and increase the measurable range of the device to be measured.

Abstract: In a digital pulse width modulation generator unit, a phase register is coupled to the clocked counter providing the generator unit time base. In response to a control signal, the contents of the phase register over-write the present counter, thereby changing the phase of pulse width modulated generator output signal. When a plurality of pulse width modulated generator units, the phases of the units can be controlled relative to a reference generator. The contents of the phase register can be altered by hardware or by software.

Abstract: An apparatus and method for extracting a maximum pulse width of a pulse width limiter are provided. The apparatus and method of the illustrative embodiments performs such extraction using a circuit that is configured to eliminate the majority of the delay cells utilized in the circuit arrangement described in commonly assigned and co-pending U.S. patent application Ser. No. 11/109,090 (hereafter referred to as the '090 application). The elimination of these delay cells is made possible in one illustrative embodiment by replacing an OR gate in the circuit configuration of the '090 application with an edge triggered re-settable latch. The replacement of the OR gate with the edge triggered re-settable latch reduces the amount of chip area used in addition to the power consumption of the circuit.

Abstract: An apparatus and method of providing a pulse width modulated signal that is responsive to a current are disclosed. A circuit according to aspects of the present invention includes a capacitor to convert a first current to a first voltage on the capacitor during a first time duration and to discharge a second current from the capacitor to change the first voltage to a second voltage during a second time duration. A comparator is also included and is coupled to an output of the capacitor to compare a voltage on the capacitor to a reference voltage during the second time duration to change a pulse width of a periodic output signal in response to an input current.

Abstract: An over-driver control signal generating apparatus includes a pulse generating unit for generating a pulse signal having a pulse width corresponding to a desired over-driving interval in response to an over-driving signal; a supply voltage level detecting unit for detecting a voltage level of a supply voltage to generate a detecting signal; and a selecting unit for outputting the pulse signal as a bit line over-driver control signal in response to the detecting signal.

Abstract: A duty cycle corrector including a restore circuit configured to receive a differential input clock and a differential feedback clock each having crossings of a first type and a second type and to provide a differential output clock having crossing of the first type based on differential input clock crossings of the first type and crossings of the second type based on differential feedback clock crossings of the first type. A delay element configured to delay the differential output clock by a delay time to provide the differential feedback clock. An adjuster circuit configured to receive the differential input and feedback clocks and to adjust the delay time so as to maintain a duty cycle of the differential output clock substantially at a desired duty cycle.

Abstract: A method and arrangement for determining the effective time of a voltage pulse of phase voltage generated by a frequency converter provided with an intermediate voltage circuit, the voltage pulses of the phase voltage being generated from the upper and lower voltage levels (UDC, 0) of the intermediate voltage circuit, the voltage levels showing a difference in potential (UDC).

Abstract: A pulse on edge circuit includes a first pull up transistor having its gate terminal coupled to a delayed control signal and a second pull up transistor having its gate terminal coupled to an inverted delayed control signal. A first and second pull down transistors are coupled in series between the first pull up transistor and a low voltage bias, wherein the gates of the first and second pull down transistors are coupled to the delayed control signal and inverted control signal, respectively. A third and fourth pull down transistors are coupled in series between the second pull up transistor and the low voltage bias. The gates of the third and fourth pull down transistors are coupled to a control signal and the inverted delayed control signal, respectively.

Abstract: A sawtooth wave generating apparatus includes a base frequency generating section and a frequency generating section for generating the frequency of a reference signal, a sawtooth wave forming section which forms a sawtooth wave based on the reference signal, a voltage comparator which compares the voltage value of the sawtooth wave formed by the sawtooth wave forming section with a predetermined voltage value, a phase comparator which compares the phase of the output signal from the voltage comparator with the phase of the reference signal, and a low-pass filter (LPF) which cuts out a high frequency component of the output signal from the phase comparator, and feeds back the resulting output signal to the sawtooth wave forming section.

Abstract: A controller that is linearly responsive to an input voltage provides continuously adjustable control of the width of a periodically repeating digital pulse, thereby achieving a linear voltage to duty-cycle ratio transfer function. The circuit of the present invention includes a master clock input, a ratio control voltage input, a controlled duty cycle clock output, a high gain amplifier configured as an integrator having differential inputs, each equipped with a low pass filter, a controlled current source, a resettable timing capacitor, a threshold detector and a reference pulse generator.

Abstract: A method and apparatus is provided to generate a pulse-width modulated (PWM) with enhanced features in accordance with a pre-determined protocol using a standard microprocessor. The method and apparatus is able to handle both variable on/off-timing control and multiple-event interrupts. The PWM functions of the present invention are implemented by software in the microprocessor that handles not only on/off events controlled by external pins, but is programmable on/off timing as well.

Abstract: Pulse-width modulation (PWM) circuits and methods integrate a feedback signal and an input signal to generate an integral signal, and generate a PWM signal by switching an output node from a first source voltage to a second source voltage based upon comparing the integral signal with a first reference voltage, and switching the output node from the second source voltage to the first source voltage based upon comparing the integral signal with a second reference voltage. A comparator unit compares the integral signal with the first and second reference (threshold) voltages, and a drive circuit for buffering the comparator unit's output signals generates drive signals. A feedback circuit generates the feedback signal based on (e.g., proportional with) the PWM signal. The switching circuit may include a P-type switch (e.g., PMOS transistor) and a N-type switch (e.g., NMOS transistor). Associated class-D audio amplifiers and modulation methods are provided.

Abstract: A system for generating a pulse signal in response to a clock signal includes a latch module for generating a latched output in response to a leading edge of the clock signal. A delay module is coupled to the latch module for delaying the latched output. A first logic device having a first input terminal coupled to the latch module and a second input terminal is coupled to the delay module for generating the pulse signal, which has a pulse width determined by a delay time of the latched output passing through the delay module. The pulse signal is coupled to the latch module for resetting the latch module when the pulse signal is not asserted.

Abstract: A duty correction device includes: a duty correction unit having a plurality of duty correction cells for selectively activating the duty correction cells according to a count signal to adjust a pulse width of an input clock and output the adjusted clock as an output clock; a phase splitter for generating a rising and a falling clocks by phase-splitting the output clock; a DCC pumping unit for generating a rising and a falling duty ratio correction signals according to a reset signal; a voltage comparing unit for generating counting increase and decrease signals according to a result of comparing the rising and the falling duty ratio correction signals in response to a comparison control signal; a comparison control unit for generating the comparison control signal and the reset signal; and a counter for increasing/decreasing a value of the count signal according to the counting increase and decrease signals.

Abstract: The present invention discloses a PWM integrated circuit which may receive a programming signal without any extra pin. The PWM integrated circuit comprises: a comparator having two outputs; two pins respectively electrically connected with the two outputs; and a programming unit electrically connected with at least one of the two pins for setting a parameter inside the PWM integrated circuit. The two pins of the PWM integrated circuit may be used to respectively control a control switch and a synchronous switch, constituting a PWM circuit for generating PWM signals.

Abstract: A memory device having a duty ratio corrector which can reduce power consumption by blocking current paths between output terminals and a ground terminal by applying input signals for turning off switching devices for generating an auxiliary voltage for correcting a duty ratio at an initial stage, and which can improve an operational speed by changing the auxiliary voltage from a predetermined voltage, not 0V, to a target voltage.

Abstract: The present invention discloses a PWM integrated circuit which may receive a programming signal without any extra pin. The PWM integrated circuit comprises: a comparator having two outputs; two pins respectively electrically connected with the two outputs; and a programming unit electrically connected with at least one of the two pins for setting a parameter inside the PWM integrated circuit. The two pins of the PWM integrated circuit may be used to respectively control a control switch and a synchronous switch, constituting a PWM circuit for generating PWM signals.

Abstract: A duty cycle corrector includes a first controllable delay, a second controllable delay, a phase detector, and a compensation circuit. The first controllable delay is configured to delay a first signal to provide a second signal. The second controllable delay is configured to delay the second signal to provide a third signal. The phase detector is configured to adjust the first controllable delay and the second controllable delay to phase lock the third signal to the first signal. The compensation circuit is configured to compensate for a mismatch between the first controllable delay and the second controllable delay to provide a fourth signal in response to the first signal and a fifth signal approximately 180 degrees out of phase with the fourth signal in response to the second signal.

Abstract: A system and method for configuring a receiver such that the duty cycle of the receiver clock accurately matches the duty cycle of the data signal received. This adaptive system and method calibrates a receiver's duty cycle to optimize the receiver timing margin for different data signal types and different slave devices. In one embodiment, a duty cycle correction circuit matches the receiver clock to a predetermined duty cycle. The receiver clock is then configured to have a duty cycle skewed from the predetermined duty cycle based on the specific data signal received. In a receiver system utilizing a clock tree, individual branches of the clock tree are configured to have respective duty cycles skewed to match the duty cycle of a data signal received from a specific transmitting device.

Abstract: Disclosed is a pulse width modulation method and apparatus capable of expressing as many values as possible in a pulse width modulation (PWM) period, while maintaining the center of pulse energy substantially equal to the center of the PWM period. For this end, prepared is the PWM pattern generator 20 including 2 kinds of PWM pulse generator 21 and 22 for generating pulses having the pulse width of 0˜N times of the reference clock period in 1 PWM period corresponding to a predetermined number N of the reference clock period. The PWM pulse generators 21 and 22 are properly switched by the switching circuit 30 under control of the control circuit 40 for performing time averaging process so that the centers of energy of the output pulses is substantially equal to the center of the PWM period.

Abstract: Embodiments may include a duty cycle controller to adjust the duty cycle of the clock signal based upon a delay signal and an input clock signal. A duty cycle detector may determine signals with frequencies based upon the duty cycle of the output signal and a correction module may compare the frequencies of the detector signals to generate the delay signal. In some embodiments, once the duty cycle of the output clock signal reaches the desired duty cycle such as fifty percent, the correction module may be turned off.

Abstract: Without shortening clock pulse duration serving as a unit time of a pulse generator, a pulse-width control is possible in which pulse duration varies in increments of a time length shorter than the unit time. A time width Ton_s of a pulse width finely dividing signal Vs from a DSP 17 varies by clock pulse duration Tclk in response to variations in an output voltage Vo. A time control circuit 18 that has received the pulse width finely dividing signal Vs generates, in a control signal Vd, varying segments 30, 31 for making the time width of the pulse drive signal Vg vary by a shorter time ?Td than the clock pulse duration Tclk. Consequently, resolution of the time width of the pulse drive signal Vg is improved so as to be higher than the clock pulse duration Tclk, which is time resolution of the DSP 17 itself.