Abstract: A signal processor includes a reference clock generator configured to generate a reference clock as a synchronization reference for a signal processing. A counter is configured to count the reference clock. A frequency controller is configured to sample a count value of the counter by utilizing an input clock, to compare an increment value increased from the last sampled value with an expected value, and to control a frequency of the reference clock in accordance with a comparison result.

Abstract: Circuits and methods are provided in which fine tuning control of a DCO (digitally controlled oscillator) circuit in a digital PLL circuit is realized by dither controlling a multiplexer circuit under digital control to selectively output one of a plurality of analog control voltages with varied voltage levels that are input to a fractional frequency control port of the DCO to drive tuning elements of the DCO at fractional frequency resolution and achieve continuous fine tuning of the DCO under analog control.

Abstract: A timing control circuit DLY1 receives clock signal CKa with period T1 and activation signal ACT and outputs fine timing signal FT with delay of m*T1+tda measured from the clock signal where m denotes a non-negative integer and tda denotes delay in the analog delay element. The timing control circuit DLY1 comprises a coarse delay circuit CD and a fine delay circuit FD. The coarse delay circuit CD comprises a counter for counting a rising edge of the clock signal CKa after receiving activation signal ACT and outputs coarse timing signal CT with delay of m*T1 measured from a rising edge of the clock signal CKa. The fine delay circuit FD comprises a plurality of analog delay elements and outputs fine delay timing signal FT with delay of tda measured from the coarse timing signal CT. Variation in delay of timing signal is reduced.

Abstract: Provided is a data recovery circuit including an input data phase detection circuit for outputting a gate signal synchronized with a rising phase of input data, a gated multiphase oscillator for instantly generating N-phase clocks based on the gate signal as a trigger, data discriminating and reproducing circuits for outputting sampled data of the input data which are synchronized with the clocks, a continuous clock generation circuit for generating a continuous clock which is a reference clock, continuous clock synchronization circuits for synchronizing the sampled data with the continuous clock and outputting the synchronized sampled data as phase synchronization data, and a phase selector for selecting the phase synchronization data having an optimum discrimination phase with the largest phase margin with respect to the input data and outputting the selected phase synchronization data as recovery data.

Abstract: A delay locked loop increases an operation margin of a delay locked loop by using an output clock having more advanced phase than a DLL output clock. A clock delay compensation block receives an external clock signal to thereby generate a first multi clock and a second multi clock. A phase control block compares the first multi clock with the second multi clock to generate phase control signal controlling a shifting operation. A multi-phase delay control block performs a shifting operation based on the phase control signal to control the clock delay compensation block.

Abstract: A simple circuit that supports high and low data rates is provided. The circuit includes: a detection circuit 11 for detecting whether D1?D2 or D1?D3, assuming that logical values of an input data signal DATAIN sampled at timings t1, t2, and t3 (t2<t1<t3) of edges of clock signals CLK0 and CLK1 are D1, D2, and D3, respectively; and a clock generation circuit 14 for changing phases of the clock signals CLK0 and CLK1 based on detection results from the detection circuit 11, so that timings at which the logical values of the input data signal DATAIN change correspond to the timings t2 and t3.

Abstract: An all digital phase locked loop circuit includes a reference frequency indicator for receiving a reference signal with a reference frequency and generating a frequency indicating value; a phase frequency detector for comparing the reference signal with a frequency divided signal and generating a phase difference pulse; a time-to-digital circuit for receiving the phase difference pulse and a plurality of output signals and generating a phase difference value; a digital controller for receiving the frequency indicating value and the phase difference value and generating a control value; a delta-sigma modulator for modulating the control value and generating a modulated control value; a DCO for receiving the modulated control value and generating an output oscillating signal with a digital controlled frequency; a frequency divider for dividing the digital controlled frequency to generate the frequency divided signal; and a multi-phase generator for receiving the output oscillating signal and generating the outp

Abstract: A digital phase-locked loop (DPLL) supporting two-point modulation with adaptive delay matching is described. The DPLL includes highpass and lowpass modulation paths that support wideband and narrowband modulation, respectively, of the frequency and/or phase of an oscillator. The DPLL can adaptively adjust the delay of one modulation path to match the delay of the other modulation path. In one design, the DPLL includes an adaptive delay unit that provides a variable delay for one of the two modulation paths. Within the adaptive delay unit, a delay computation unit determines the variable delay based on a modulating signal applied to the two modulation paths and a phase error signal in the DPLL. An interpolator provides a fractional portion of the variable delay, and a programmable delay unit provides an integer portion of the variable delay.

Abstract: There is provided an apparatus for the linearization of a digitally controlled oscillator. The apparatus includes a first filter outputting only a low frequency band signal of an input signal to the digitally controlled oscillator; a negative feedback loop causing the signal of an input port of the digitally controlled oscillator to pass through a frequency table and a frequency-to-digital code mapper in sequence and correcting an input of the digitally controlled oscillator by performing negative feedback to an input port of the first filter; and a frequency table generator storing a frequency value of an output signal of the digitally controlled oscillator in the frequency table.

Abstract: An all-digital phase locked loop (ADPLL) generates a feedback word representing a continuous-time oscillating signal. The ADPLL includes a time-to-digital converter (TDC) configured to be input with the continuous-time oscillating signal and a reference signal. The reference signal is a function of a reference clock signal. The TDC is configured to generate a digital word, the feedback word being a function of the digital word. The ADPLL includes a delay circuit configured to be input with at least one of the reference clock signal and the continuous-time oscillating signal and to be controlled by a first dither signal.

Abstract: A power supply circuit includes a first voltage regulator to generate a first supply voltage for a first circuit of a phase-locked loop and a second voltage regulator to generate a second supply voltage for a second circuit of the phase-locked loop. The first and second supply voltages are independently generated by the first and second voltage regulators based on the same reference signal. The first circuit may be a charge pump and the second circuit may be a voltage-controlled oscillator. Different circuits may be supplied with the independently generated supply voltages in alternative embodiments.

Abstract: The phase locked loop (PLL) with adjustable phase shift is described. The PLL includes a voltage controlled oscillator which is capable of generating multiple phase shifted output signals, and multiple phase detectors capable of determining the phase differences between the output signals and a reference clock. The PLL further includes a weighting device capable of weighting the phase differences and generating a control signal for the voltage controlled oscillator.

Abstract: The phase controller device according to the invention comprises a hardware core that is formed by a signal detector, a voltage-controlled oscillator, a phase comparator, and an integration unit, where the hardware core, by controlling the working clock pulse frequency of the microcontroller, brings an output clock pulse signal that is generated by a microcontroller into phase with the input clock pulse information that is received from the input data stream, and does so in such a manner that the jitter is low. The microcontroller executes a program with this working clock pulse, where with that program the microcontroller generates the output clock pulse signal with an output clock pulse frequency that is in a predetermined division ratio to the control clock pulse frequency that is generated by the voltage-controlled oscillator and is given to the microcontroller as a working clock pulse frequency.

Abstract: Provided is an analog/digital control delay locked loop (DLL). The DLL includes a phase detector for detecting a phase difference between an input clock signal and a feedback signal to provide an up detection signal or a down detection signal, a charge pump for generating an adjusted output current based on the up or down signals, a loop filter for low pass-filtering the output current to produce an analog control voltage, a voltage controlled delay Line (VCDL) for receiving the analog control voltage, the input clock signal and a digital code, and delaying the input clock signal based on the analog control voltage and the digital code to provide an output clock signal, a delay replica modeling unit formed by replica of delay factors for producing the feedback signal depending on the output clock signal, and a digital code generator for generating the digital code.

Abstract: Systems and methods for design and operation of signal generator circuitry with output frequencies greater than the oscillator frequency. Accordingly, in a first method embodiment, a method of producing an output periodic electronic signal comprises accessing four signals having a quadrature phase relationship. First and second pairs of these signals having a one half cycle phase relationship are averaged to produce two signals having an improved duty cycle and a one-quarter cycle phase relationship. The first and second averaged periodic electronic signals are combined in an exclusive OR circuit to produce the output periodic electronic signal at twice the oscillator frequency. Advantageously, the periodic signal may comprise a desirable duty cycle of 50 percent.

Abstract: A timing recovery system and method for accelerated clock synchronization of remotely distributed electronic devices is provided. The system includes a phase locked loop, a linear estimator and control logic. The method includes sampling a clock signal received from an electronic device, applying a linear estimation technique to estimate the frequency and phase of the received signal and providing those estimates to a phase locked loop to accelerate the phase locked loop acquisition rate and secure signal lock quickly.

Abstract: A device and a method for generating a output clock signal having a output cycle, the method includes: (i) adjusting a delay of an adjustable ring oscillator to provide a high frequency clock signal having a short cycle so that the output cycle substantially equals a sum of integer multiples of a sleep cycle and integer multiplies of the short cycle; wherein the output cycle differs from any integer multiples of the sleep cycle; wherein the sleep cycle characterizes a sleep clock signal that is generated by a low frequency sleep clock; wherein the short cycle is shorter than the sleep cycle; (ii) counting short cycles and sleep cycles; and (iii) generating, during a sleep mode, in response to the counting and to a predefined counting pattern, the first clock signal; wherein the generating includes activating the adjustable ring oscillator only during a portion of a single sleep cycle per each output cycle.

Abstract: A digital loop filter includes a fine control circuit and a coarse control circuit. The fine control circuit adjusts a phase of a feedback clock signal by a first phase adjustment in response to a first phase error signal that indicates a sign of a phase error between a reference clock signal and the feedback clock signal. The coarse control circuit adjusts the phase of the feedback clock signal by a second phase adjustment in response to a second phase error signal. The second phase adjustment is larger than the first phase adjustment. The second phase error signal indicates a magnitude of a phase error between the reference clock signal and the feedback clock signal.

Abstract: An apparatus for implementing a digital phase-locked loop includes a voltage-controlled oscillator that generates a primary clock signal in response to a VCO control voltage. Detection means generates counter control signals, including count up signals and count down signals, to indicate a current relationship between the primary clock signal and a reference signal. An up/down counter then either increments or decrements a counter value in response to corresponding counter control signals. The counter value is then converted by a digital-to-analog converter into the VCO control voltage for adjusting the frequency of the primary clock signal generated by the voltage-controlled oscillator. In alternate embodiments, the foregoing up/down counter may be utilized to adjust the frequency of the voltage-controlled oscillator in proportion to the counter value by utilizing appropriate techniques other than generating a VCO control voltage with a digital-to-analog converter.

Abstract: A power-down mode control apparatus includes an internal power-down control block configured to receive a locking completion signal and to generate an internal power-down signal, which is toggled for a predetermined time; a noise check block configured to check occurrence/non-occurrence of noise on the basis of a phase detection signal and to generate a plurality of power-down selection signals in response to the locking completion signal and the internal power-down signal; and a power-down enter control block configured to generate a plurality of power-down enter signals, which instruct individual circuits to enter a power-down mode in response to a reference clock signal, the plurality of power-down selection signals, a power-down mode signal, and the internal power-down signal.

Abstract: Techniques for adaptively calibrating a TDC output signal in a digital phase-locked loop (DPLL). In an exemplary embodiment, a calibration factor multiplied to the TDC output signal is adaptively adjusted to minimize a magnitude function of a phase comparator output signal of the DPLL. In an exemplary embodiment, the calibration factor may be adjusted using an exemplary embodiment of the least-mean squares (LMS) algorithm. Further techniques for simplifying the adaptive algorithm for hardware implementation are described.

Abstract: A Delay Locked Loop (DLL) and method for generating multiple equally spaced phases over a wide frequency range is disclosed. The DLL includes a delay line, and a control module. The delay line receives a reference clock signal and outputs a final delay clock signal in response to the reference clock signal. The delay line includes a plurality of delay cells connected in series. The plurality of delay cells generate a plurality of delay clock signals having equally spaced phases. The control module generates a phase control signal based on counting a number of pulses of the reference clock signal that are input to the delay line before occurrence of a first corresponding pulse of the final delay clock signal.

Abstract: Provided are a lock detection circuit and a lock detecting method. The lock detection circuit includes two delay devices, four flip-flops and two logic gates, and can accurately detect a lock state of a phase locked loop (PLL) circuit. Therefore, the lock detection circuit can be implemented in a simple structure, and as a result, the lock detection circuit can be compact in size and can consume less electric power. Also, the lock detecting method enables lock detection process to be simpler, so that a lock state can be detected within a short time period.

Abstract: A clock generator having a delay locked loop and a delay control circuit. The delay locked loop receives an input clock signal and adjusts an adjustable delay circuit to generate an output clock signal that is synchronized with received input clock signal. The delay control circuit coupled to the delay locked loop generates a control signal to initialize the delay measure operation to adjust the adjustable delay circuit, after comparing the phase difference of the input clock signal and the output clock signal. The delay control circuit further generates a start measure control signal to start measuring a delay applied to the measurement signal propagating through the adjustable delay circuit, and generates a stop measure control signal to stop the delay measurement of the measurement signal. The delay adjustment of the delay locked loop is then adjusted to apply the delay measurement when synchronizing the input and output clock signals.

Abstract: Techniques for converting an accumulated phase of a signal into a digital value in a digital phase-locked loop (DPLL). In an exemplary embodiment, a signal is coupled to a divide-by-N module that divides the frequency of the signal down by a divider ratio N. The divided signal is input to a delta phase-to-digital converter, which measures the phase difference between a rising edge of the divided signal and a rising edge of a reference signal. The accumulated divider ratios and the measured phase differences are combined to give an accumulated digital phase. Further techniques for varying the divider ratio N using a sigma-to-delta modulator are disclosed.

Abstract: A (DFLL) circuit residing on a local core of a multi-core microprocessor for generating a local core clock with a frequency for driving the local core includes a micro-controller configured to receive core characterizing digital data; a ring oscillator configured to generate the local core clock for the local core, and having a delay chain disposed between an output and a feedback input of the ring oscillator, the delay chain having delay taps each receiving the local core clock enabling quantum changes in the frequency of the local core clock; and a counter device configured to continually validate the frequency by generating a digital signal representative of the frequency to the micro-controller, the micro-controller compares the frequency of the local core clock to a desired clock frequency, and selects one of the delay taps based on the comparison to adjust the frequency value of the local core clock.

Abstract: A digitally controlled PLL oscillation circuit has a VCO, a frequency divider, a reference oscillation circuit, an A/D converter, a phase comparator, a digital filter, a D/A converter, and an analog filter. A reference signal supplied from the reference oscillation circuit is output through a narrow-band crystal filter (MCF) to the A/D converter to cancel noise, jitter and a spurious wave included in the reference signal, making it possible to prevent the phase noise characteristic and spurious characteristic of a VCO output from being degraded.

Abstract: A wireless communication device is disclosed wherein isolation buffers couple to respective active circuits or stages of the device to convey test information regarding such active circuits to a test data line from which status information may be collected. The communication device operates in two modes, namely a normal operational mode wherein the isolation buffers effectively short spurious emissions from the active circuits to a ground, and a test mode wherein the isolation buffers may convey test information from a selected active circuit to the test data line. The isolation buffers prevent spurious emissions from escaping the active circuits to which they are coupled and prevent spurious emissions from traveling from active circuit to active circuit over the test data line throughout the wireless device.

Abstract: A digital delay line includes a plurality of hysteresis-based delay cells electrically connected in series. These hystersis delay units in the hysteresis-based delay cells may be similar or different. All of the hysteresis delay units respectively have an inverter mode and a hesteresis mode. The delay and resolution of the hysteresis delay unit may be derived from the time difference in the inverter mode and hysteresis mode. Such a digital delay line applied to a digital phase locked loop may reduce consumption of area and power.

Abstract: PLL (phase locked loop) circuits and methods are provided in which PWM (pulse width modulation) techniques are to achieve continuous fine tuning control of DCO (digitally controlled oscillator) circuits. In general, pulse width modulation techniques are applied to further modulate dithered control signals that are used to enhance the frequency tuning resolution of the DCO such that the dithered control signals are applied to the fractional tracking control port of the DCO for a selected fraction of a full clock signal based pulse width modulation applied.

Abstract: Circuits and methods are provided in which fine tuning control of a DCO (digitally controlled oscillator) circuit in a digital PLL circuit is realized by dither controlling a multiplexer circuit under digital control to selectively output one of a plurality of analog control voltages with varied voltage levels that are input to a fractional frequency control port of the DCO to drive tuning elements of the DCO at fractional frequency resolution and achieve continuous fine tuning of the DCO under analog control.

Abstract: A frequency detecting and converting apparatus comprises a plurality of frequency-dividers, a multiplexer, a pulse width detector, a comparing unit and an encoder. The invention automatically detects the operating frequency of an input clock signal, divides the frequency of the input clock signal by a pre-defined integer according to the detected operating frequency and finally generates an output clock signal with an operating frequency required for an integrated circuit.

Abstract: A phase discriminator for being used in a phase-locked loop to determine if a phase difference between a reference signal and a target signal has reached a programmable gap value is disclose which comprises a programmable phase gap selector receiving the reference signal, a first phase digital converter converting an output signal from the programmable phase gap selector to a first digital code, a second phase digital converter converting a phase difference between the target signal and the reference signal to a second digital code, and a code comparator comparing the first and second digital code and generating a first instructional signal based on a change of order of the values of the first and second digital code.

Abstract: An input clock dividing unit frequency-divides an input clock, and an input clock multiplying unit frequency-multiplies the input clock. An operation clock selecting unit selects the frequency-divided clock when the input clock is fast and selects the frequency-multiplied clock when the input clock is slow, based on the frequency detection result of frequency detecting unit. The operation clock selecting unit then outputs the selected clock to a phase comparing unit as an operation clock. The phase comparing unit operates according to the frequency-divided or frequency-multiplied clock, and controls an oscillating unit so that the phase difference between a reference signal and a comparison signal becomes zero. The phase of an output clock is thus caused to track the phase of the reference signal.

Abstract: A DLL circuit includes a first delay line circuit, a first phase comparison circuit, a control circuit, and a first selecting circuit. The first delay line circuit can change a delay amount and provide a delay to a first clock signal. The first phase comparison circuit can detect a phase difference between the first clock signal and an output signal of the first delay line circuit, and a phase difference between a test clock signal of which frequency is lower than the first clock signal and an output signal of the first delay line circuit or a signal after dividing the output signal. The control circuit controls a delay amount of the first delay line circuit according to the detection result of the first phase comparison circuit.

Abstract: A phase determination section determines the quantity of first fixed delay elements for delaying a clock signal by one cycle and generates a selection signal indicating the determination result. A phase adjustment section determines, based on the selection signal, the quantity of second fixed delay elements for delaying an input signal and generates the output signal by delaying the input signal by a certain phase amount. The phase adjustment section includes a variable delay unit which generates, based on the selection signal, a variable delay time allowing the delay time of the output signal to be adjusted in steps of ½n the delay time of one of the second fixed delay elements.

Abstract: Provided are a delay locked loop (DLL) and a method for generating a divided clock therein. In the DLL, a width of a reference frequency for phase comparison can be changed depending on a magnitude of an operating frequency. In the DLL, a clock buffer receives a clock equal to an external clock and generates an internal clock. An enable clock generator generates a 1-period enable clock or a 2-period enable clock using a command signal generated for performing a predefined operation. The command signal is generated according to an address command signal inputted from an exterior. A clock divider divides the internal clock to generate a divided clock. The divided clock is controlled by the 1-period enable clock or the 2-period enable clock, such that the divided clock is made to be a 1-period based dividing clock or a 2-period based dividing clock.

Abstract: A delay locked loop circuit includes a phase detector configured to compare a phase of a reference clock signal with a phase of an output clock signal and to output a comparison signal, a control voltage generator configured to output a control voltage based on the comparison signal, a voltage controlled delay line comprising a plurality of delay elements and configured to delay the reference clock signal based on the control voltage and to output the output clock signal, and a control voltage initializer configured to generate digital codes based on characteristics of the voltage controlled delay line and to generate an initial control voltage based on the digital codes.

Abstract: A method and circuitry for a Delay Locked Loop (DLL) or a phase Locked Loop (PLL) is disclosed, which improves the loop stability at high frequencies and allows maximum tracking bandwidth, regardless of process, voltage, or temperature variations. Central to the technique is to effectively operate the loop at a lower frequency close to its own intrinsic bandwidth (1/tLoop) instead of at the higher frequency of the clock signal (1/tCK). To do so, in one embodiment, the loop delay, tLoop, is measured or estimated prior to operation of the loop. The phase detector is then enabled to operate close to the loop frequency, 1/tLoop. In short, the phase detector is made not to see activity during useless delay times, which prevents the loop from overreacting and becoming unstable.

Abstract: A design structure for an impedance matcher that automatically matches impedance between a driver and a receiver. The design structure for an impedance matcher includes a phase-locked loop (PLL) circuit that locks onto a data signal provided by the driver. The impedance matcher also includes tunable impedance matching circuitry responsive to one or more voltage-controlled oscillator control signals within the PLL circuit so as to generate an output signal that is impedance matched with the receiver.

Abstract: In an ADPLL composed of a digital circuit, a technique improving phase difference detection in a vicinity of a phase difference of 0 (zero) is provided. A feedback loop comprises a PFD comparing phases and frequencies of a reference signal and a feedback signal, a TDC converting an output of the PFD into a digital value, a DLF removing a high frequency noise component from an output of the TDC, a DCO controlled based on an output of the DLF and a DIV frequency-dividing an output the DCO and outputting the feedback signal. An offset value is added at any portion of the feedback loop, a phase of the feedback signal is controlled and a value other than 0 is inputted to the TDC even when the ADPLL is locked.

Abstract: An electric circuit, for use in a phase lock loop circuit, the electric circuit comprising: a first circuit element, being a phase frequency detector or a charge pump; at least one LC resonant loop, the first circuit element forming part of the loop; and means arranged to reduce ringing in said at least one LC resonant loop.

Abstract: A hybrid analog/digital phase-lock loop with high-level event synchronization provides a mechanism for generating a low-jitter clock from a timing reference that has a high jitter level and synchronizing the output clock to high-level events. A numerically-controlled analog oscillator provides a clock output and a counter divides the frequency of the clock output to provide input to a digital phase-frequency detector for detecting an on-going phase-frequency difference between the timing reference and the output of the counter. A synchronization circuit detects or receives a high-level event signal, and resets the on-going phase-frequency difference and optionally the counter to synchronize the clock output with the events. The synchronization circuit may have an arming input to enable the synchronization circuit to signal a next event. Another clock output divider may be included to generate a timing reference output, and the other clock divider also reset in response to a detected event.

Abstract: A PLL (phase locked loop) system includes a PLL and a lock detector. The PLL is for outputting a phase-locking clock signal. The lock detector is coupled to the PLL for detecting whether or not the frequency of the phase-locking clock signal falls within a predetermined frequency range and detecting whether or not the phase-locking clock signal is stable. If the frequency of the phase-locking clock signal has fallen within the predetermined frequency range and the phase-locking clock signal is stable by detection, the lock detector outputs a lock signal.

Abstract: An adjustable digital lock detector for a phase-locked loop (PLL) has a variable counter for outputting an output signal corresponding to a first clock signal, a target count number signal, and a count number offset signal, a latch for sampling the output signal of the variable counter and outputting a latch output signal according to a result of sampling the output signal, a lead/lag detector for receiving the latch output signal and outputting the count number offset signal according to a predetermined state of the latch output signal, and an arbiter for receiving the latch output signal and outputting an arbiter output signal according to the latch output signal and a second clock signal.

Abstract: A digital delay locked loop circuit generates a delay value to delay the timing of taking in read-data by a memory interface when data is read from a memory. The digital delay locked loop circuit includes a selector that selects either one of a clock signal and a data strobe signal as a signal to output; a delay line that induces delay on the signal output from the selector when the signal passes through the delay line; and a phase-comparing/delay-value determining unit that compares a phase of the clock signal and a phase of the signal output from the delay line, and that determines a delay value that defines an amount of delay to be induced on the data strobe signal when passing through the delay line.

Abstract: A control system for generating an electronic circuit clock signal that can optimize operating frequency margins by responding to short term effects by quickly varying the clock frequency and long term effects by finding an optimal frequency point. A sensor indicates frequency margins associated with safe use of the clock signal, and these frequency margins are input into a frequency compensator and used to determine whether the system is operating within acceptable margins, or alternatively to modify the operating clock frequency on a short-term basis in order to achieve acceptable operating margins. The requests for frequency adjustment by the frequency compensator are provided to a frequency filter, which combines such request with a maintained/accumulated history of previous short-term frequency requests that have previously been made in order to determine whether an update needs to be made to the target frequency to provide long-term frequency control.

Abstract: Embodiments of the invention include an integrated circuit including a phase-locked loop (PLL). The integrated circuit includes a phase detector, a frequency detector, a loop filter, a digitally-controlled oscillator and a corresponding plurality of frequency dividers. The phase detector generates a first binary output based on a phase comparison of a reference clock signal to a plurality of clock phase inputs. The frequency detector generates a second binary output based on a frequency comparison of the reference clock signal to the clock phase inputs. The loop filter generates a third binary output based on the first binary output and the second binary output. The DCO feeds back the clock phase inputs, via the frequency dividers, to the phase detector based on the third binary output, and feeds back one of the clock phases to the frequency detector based on the third binary output.

Abstract: A technique to mitigate noise spikes in an electronic circuit device such as an integrated circuit. The clock frequency of a clock signal used by the electronic circuit is controlled such that instantaneously large changes to the clock frequency are avoided by use of a frequency filter that is capable of generating frequency ramps having a linear slope which is used as a feedback signal in a digital phase-locked loop clock circuit in lieu of a discrete, stair-stepped feedback control signal.

Abstract: In an apparatus and method for reducing current leakage in a phase locked loop (PLL), a pair of resistive divider circuit is coupled to receive a pair of differential input signals and provide a pair of differential output signals. A timing control circuit controls a pair of switches, the pair of switches being operable to conduct the pair of differential output signals in response to at least one signal of the pair of differential input signals being present. An operational amplifier (OA) includes a pair of OA input terminals and an OA output terminal. The pair of OA input terminals is coupled to receive the pair of differential output signals conducted by the pair of switches. A feedback circuit is coupled between the OA output terminal and a first one of the pair of OA input terminals. The pair of switches is disabled by the timing control circuit to block a current leakage from the feedback circuit.