Abstract: A phase detecting module includes a phase detecting unit, a comparator and a counter. The phase detecting unit is arranged to compare a first input signal and a second input signal to generate a phase detecting result. The comparator is arranged to compare the phase detecting result and a predetermined voltage to generate a comparing result. The counter is arranged to count one of the first input signal and the second input signal to generate a counting value. The phase detecting result and the counting value are reset if the counting value reaches a predetermined value, and the comparing result is outputted to a target device from the comparator if the counting value reaches a predetermined value.

Abstract: A high-accuracy phase detector circuit compatible with a 1/N rate architecture is provided. The phase detector circuit has as many as N track-and-hold circuits for tracking and holding N-phase clock signals CLK—1 to CLK_N in synchronization with a rising edge of input data signal DIN. Out of the N-phase clock signals CLK—1 to CLK_N outputted from as many track-and-hold circuits, only the one whose rising edge is most synchronized with a rising edge of the input data signal DIN is selected and outputted as a phase difference signal.

Abstract: Disclosed herein is a method and apparatus used to detect phase error information between edges of an input data signal and a clock signal for use at ultra-high frequencies and where linear phase error information is required. This invention extends the usefulness of a given integrated circuit logic technology to twice the frequency range of application while maintaining the desired linear phase error measurement operation. Flip flops are used to sample the data input signal with the clocking signal and processing is done separately for rising and falling data edges. Analog recombination of phase error information from both edges is then done in a fashion that is not limited by the integrated circuit speed.

Abstract: Provided is a frequency lock detector which includes one counter and a clock number difference detector for detecting a clock number difference while not increasing complexity according to the counting number N to compare the frequencies of two clock signals whose phases are not synchronous to each other and determine whether the difference between the frequencies of the two signals is within a desired frequency accuracy. The frequency lock detector includes: a counter for counting the number of clocks of a reference clock signal inputted from outside; a clock number difference detector for detecting a difference between the clock number of the reference clock signal and the clock number of a recovered clock signal whose phase is not synchronous to the phase of the reference clock signal; and a lock determiner for determining a frequency lock based on result values of the counter and the clock number difference detector.

Abstract: A method and circuit for static phase error measurement includes a reference clock delay chain having a selectable number of delay elements. A number of the delay elements are enabled in accordance with a select length signal to delay a reference clock signal. A feedback signal delay chain also has a selectable number of delay elements. A number of the delay elements are enabled in accordance with a select length signal to delay a feedback signal. A latch tests phase alignment between the delayed reference clock signal and the delayed feedback signal and outputs a measurement of static phase error.

Abstract: A digital phase detector is provided that can be easily implemented in gate array or FPGA, to accurately quantize a phase difference of two clocks and convert to a digital value without using delay elements. The digital phase detector includes: a multiplier for, when two clocks have frequencies close to an integer ratio, receiving a first clock and multiplying by M/N; F/F for latching a second clock by an output clock of the multiplier; a differential circuit for differentiating an output of the F/F; a counter for receiving the output clock of the multiplier; a latch circuit for holding an output of the counter according to an output of the differential circuit; a first adder for adding an output of the latch circuit; a second adder for subtracting an output of the first adder from a fixed value; and an accumulator for sequentially integrating an output of the second adder.

Abstract: It is an object of the present invention to improve the phase difference detection accuracy of a phase comparator. A phase difference signal generation circuit outputs a signal C_SIGNAL which takes a high level for a period corresponding to the phase difference between the comparison target signals COMP1 and COMP2 to the control terminal of a tri-state buffer, based on a signal synchronous with the start-up of the comparison target signal COMP1 detected by an edge detection flag generation circuit and a signal synchronous with the start-up of the comparison target signal COMP2 detected by an edge detection flag generation circuit. A status management circuit outputs a signal A_SIGNAL corresponding to the phase advance or delay of the comparison target signals COMP1 and COMP2 to the input terminal of the tri-state buffer.

Abstract: A phase comparing circuit includes a first storage circuit for reading an external clock signal based on a control clock signal; first and second inverters for inverting a signal from the first storage circuit based respectively on first and second threshold levels; third and fourth inverters for inverting respective signals output from the first and second inverters; a delay circuit for delaying the control clock signal by a specific time; a coincidence control circuit for setting the delayed control clock signal to be active when the signals from the third and fourth inverters coincide with each other, and setting it to be inactive when the signals from the third and fourth inverters do not coincide with each other; and a second storage circuit for reading a signal output form the first storage circuit when the delayed control clock signal is active, and outputting the read signal as the control signal.

Abstract: A method of generating a correction signal for a voltage controlled oscillator (VCO) includes receiving a first signal in a correction current generator, changing a state of a first error signal substantially simultaneously with a first changing state of the first signal, receiving a second signal in the correction current generator, changing a state of a second error signal substantially simultaneously with a first changing state of the second signal, changing the state of the first error signal substantially simultaneously with a second changing state of the second signal, changing the state of the second error signal substantially simultaneously with a second changing state of the first signal, combining the first error signal and the second error signal to generate the correction signal substantially equal to a difference between the first error signal and the second error signal and applying the correction signal to a loop filter coupled to a correction signal input of the VCO.

Abstract: This invention relates to fault detection in electrical circuits. The invention provides a method and apparatus for testing an input circuit by generating a periodic test signal having a predetermined phase and a predetermined amplitude; summing the test signal and an input signal to provide a summed signal; processing the summed signal to provide an output signal; generating an extracted test signal from the output signal; comparing the extracted test signal with a reference signal representing said periodic test signal; generating an error signal in dependence upon the result of said comparing step. The invention also provides a method and apparatus for testing a plurality of adjacent input circuits.

Abstract: A phase detector apparatus and method used for clock recovery from a data signal is provided. The phase detector provides phase correction signals to a clock signal generator, where the phase correction signals are only generated if a predetermined data sample pattern is observed. In particular, the predetermined data sample pattern is preferably a transition from one to zero. Thus, transitions from zero to one will not provide a valid phase update output signal, even though a transition has occurred. In other embodiments the predetermined data sample pattern is preferably a one to zero transition preceded by an additional logic one sample.

Abstract: An automatic phase detection circuit for generating an internal synchronization signal when two clock input signals achieve a certain phase relationship. No external reference signal is required. The logic state of one clock is sampled on the active edge of the other clock and stored in a shift register. The content of the shift register is compared to a pre-defined signature and a sync signal is generated when the content matches the pre-defined signature. A mask register may be used to define which bits of the shift register and pre-defined signature are compared.

Abstract: A frequency synthesizer. The frequency synthesizer comprises a harmonic locked phase/frequency detector, a low pass filter, a voltage controlled oscillator, and a frequency divider. The harmonic locked phase/frequency detector receives a reference signal and a divided signal. The low pass filter is coupled to the harmonic locked phase/frequency detector. The voltage controlled oscillator is coupled to the low pass filter and provides an output signal. The frequency divider is coupled between the voltage controlled oscillator and the harmonic locked phase/frequency detector. Frequency of the divided signal is a harmonic frequency of the reference signal.

Abstract: A method and circuit for phase and frequency detection having zero static phase error for use in a phase-locked loop system is presented. The phase and frequency detector utilizes a first phase and frequency detector configured to generate first and second pulsed PFD signals. Pulse blocking circuitry is utilized to provide first and second output signals based on the first and second pulsed signals respectively, wherein a time period when both first and second output signals are asserted is substantially reduced from a time period when both first and second pulsed signals are asserted. By reducing the time the first and second output signals are simultaneously asserted, the effects of charge pump current source mismatch are minimized and static phase error is reduced.

Abstract: A method comprises applying a first delay to a first signal that is ahead of a second signal in a series of signals and determining a first number of delay units that provides the first delay to change an order between the delayed first signal and the second signal that has a phase difference with the first signal. The method further comprises determining a similar number for any other pair of signals in the series of signals that have the phase difference. The method further comprises determining a maximum and a minimum from the obtained numbers and determining linearity of the seriels of signals based on a difference between the maximum and the minimum.

Abstract: A phase/frequency detector has a modulo counter for outputting a counter word with a predetermined word length depending on an oscillator signal. In addition, a modulo integrator for outputting an integrator word with the predetermined word length as a function of integration of a channel word is provided. The phase/frequency detector also has a difference element for outputting a phase error word with the predetermined word length as a function of a difference between the counter word and the integrator word.

Abstract: A phase frequency detector with two different delays is disclosed herein. The phase detector comprises a first D flip-flop, a second D flip-flop, a first delay unit and a second delay unit. The first D flip-flop receives a reference signal to output an up signal. The second D flip-flop receives a clock signal to output a down signal. The first delay unit delays the received signal with a first delay. The second delay unit delays the received signal with a second delay. When the reference signal synchronizes with the clock signal and the charge pump currents are calibrated, the high-level pulse widths of the up signal and the down signal are determined based on the first delay, and when the reference signal does not synchronize with the clock signal and the charge pump currents are not calibrated, the high-level pulse widths of the up signal and the down signal are determined based on the second delay.

Abstract: A method for comparing phases of two signals including placing a first output node in a floating state, detecting a first edge of a first signal on a first input node after placing the first output node in the floating state, coupling the first edge of the first signal to the first output node and resetting the first output node to the floating state after coupling the first edge of the first signal to the first output node. A system for comparing phases of two signals can also be included.

Abstract: A PLL and DLL are designed such that the power consumption can be reduced, the size can be easily reduced, the band of the locked loop can be a higher one, and the reliability can be improved. There are provided a phase comparator for measuring a feedback signal in synchronism with an input signal and outputting a phase signal representing the lead or lag of the phase of the feedback signal, a counter for increasing the number of bits representing “H” in a control signal when the phase signal represents the lead or decreasing the number of bits representing “H” in the control signal when the phase signal represents the lag, and a ring oscillator for increasing the oscillation period when the number of bits representing “H” increases or decreasing the oscillation period when the number of bits representing “H” decreases.

Abstract: A clock signal detector is provided. The device comprises a plurality of signal delayers and a plurality of flip-flops for comparing the offset range of the clock signal between two different groups, and transmitting the resulted signal to a phase compensator, which is used to send a regulating clock signal to a clock generator. Therefore, the offset ranges of the clock signals from two different groups will be within the range of the system requirement, such that it can optimize the system operation.

Abstract: A phase detecting circuit having an adjustable gain curve includes a plurality of phase detectors and a logic circuit. The phase detectors detect phase differences between a data signal and a plurality of clock signals by comparison to output a plurality of control signals. The clock signals have the same frequency but different phases, and the frequency of the data signal is a multiple of the frequency of the clock signals. The logic circuit performs various logic operations according to these control signals to output at least one set of gain control signals for adjusting a gain curve of the phase detecting circuit.

Abstract: A pattern sequence and state transition trigger generator provides a trigger when a specified transition from one pattern/state to another pattern/state occurs in a set of input signals. Decoders detect each specified pattern/state from the set of input signals to produce a prior value and a current value representing the transition. The prior value is slightly delayed and combined with the current value to produce an overlap when the specified transition occurs, which in turn generates the trigger.

Abstract: A phase-difference detecting method is for detecting phase difference between a first signal and a second signal of the same frequency. First, generate a detection signal. Next, sample the detection signal respectively according to the first signal and the second signal to obtain a first sample value and a second sample value. Then, determine whether a determination condition that the first and the second sample values are respectively equal to the previous first and second sample values is satisfied. When the determination condition is unsatisfied for the first time, record a delay time of the detection signal as a first time. When the determination condition is unsatisfied for the second time, record a delay time of the detection signal as a second time. Obtain the phase difference between the first signal and the second signal according to the first time and the second time.

Abstract: There is provided a phase detection apparatus that can accurately detect a phase difference between an input signal and a reference signal even when the input signal and the reference signal have different duty cycles. A phase detection apparatus according to an aspect of the invention may include: a pulse generation unit generating a first pulse signal on an edge of an input pulse signal, and a second pulse signal based on an edge of a reference pulse signal having a predetermined phase; and a detection unit detecting a phase difference between the first pulse signal and the second pulse signal from the pulse generation unit.

Abstract: A PLL and DLL are designed such that the power consumption is reduced, the size is reduced, the band width of the locked loop is increased, and the reliability is improved. There are provided a phase comparator for measuring the value of a feedback signal in synchronism with an input signal and outputting a phase signal representing the lead or lag of the phase of the feedback signal, a counter for increasing by one the number of bits representing “H” in a control signal when the phase signal represents the lead of the phase or decreasing by one the number of bits representing “H” in the control signal when the phase signal represents the lag of the phase, and a ring oscillator for increasing the oscillation period when the number of bits representing “H” in the control signal increases or decreasing the oscillation period when the number of bits representing “H” decreases.

Abstract: Bang-bang phase detection (BBPD) methods and circuits are presented for providing low latency, low jitter phase detection for use in high data-rate applications. A shortened data-path implementation of BBPD methods and circuits provides low-latency production of two output signals including alternating samples of the input signal. Combinational logic circuitry is also provided to produce a clock-data recovery (CDR) signal indicative of the phase of the input signal with respect to a clock signal. The use of differential signals throughout the BBPD timing circuitry provides for the production of a low jitter CDR signal.

Abstract: A radiation hardened phase frequency detector (PFD) is provided for implementing enhanced radiation immunity performance. The radiation hardened phase frequency detector (PFD) includes a plurality of functional blocks. Each functional block includes duplicated components providing duplicated inputs, internal nodes and outputs. The duplicated components are arranged so that when there is a SEU hit to one node and the duplicated node supports the functionalities of the PFD.

Abstract: Methods and apparatus are disclosed, such as those involving a digital phase detector that includes a phase detection circuit configured to detect which one of two clock signals leads the other. One such phase detector includes a balancer configured to prepare the phase detection circuit for a phase detection. The phase detection circuit of one or more embodiments includes a cross-coupled latch configured to receive the two clock signals and generate a first latch output and a second latch output in response to the two clock signals. The aforementioned balancer is configured to substantially equalize the voltage levels of the first and second latch outputs before the phase detection circuit detects a phase difference between the two clock signals. For example, the balancer might pre-charge the outputs of the phase detection circuit to substantially the same voltage level before phase detection.

Abstract: Known phase detectors have feedbackloops and do not function properly under severe conditions. By providing said phase detectors with difference establishers (1) for establishing differences between input signals and with selectors (2) for selecting one of said differences to be used as an output signal for phase locking purposes, the phase detectors operate better under more severe conditions, with any dead-zone having disappeared. Said selector (2) is a feedbackless selector, then a loop delay no longer exists, the linear range will not get any smaller for higher frequencies, the output jitter will not increase, for sampled input signals. Said selector (2) comprises latches (21,22) and a multiplexer (23). A converter (3) converts input signals into compensated input signals, via a buffer circuit (31,33) coupled to a replica circuit (32,34) per input signal, to provide input signals having substantially equal amplitudes and being compensated with process errors and temperature variations.

Abstract: The present invention provides a method and an apparatus for reducing noise. The apparatus includes a phase detector adapted to determine a phase difference between a first and a second signal, a first circuit adapted to generate a control signal based upon the determined phase difference, and a second circuit. The second circuit is adapted to receive a third signal, receive a fourth signal, modify the fourth signal based upon the control signal, and provide the third signal and the modified fourth signal to the phase detector as the first and second signals.

Abstract: A circuit for reducing phase distortion of a first signal and a second signal is provided, wherein the first and the second signals are complementary. The circuit includes a detecting circuit for detecting a first edge of the first signal and a second edge of the second signal, wherein the second edge immediately follows the first edge and is in a same direction as the first edge; an output node; and a signal regenerator connected to the detecting circuit and the output node. The signal regenerator is configured to generate an output signal having an additional first edge and an additional second edge. The additional first edge and the additional second edge are opposite edges substantially aligned to the first edge and the second edge, respectively. The additional first edge and the additional second edge are immediate neighboring edges.

Abstract: A method and radiation hardened phase frequency detector (PFD) are provided for implementing enhanced radiation immunity performance. The radiation hardened phase frequency detector (PFD) includes a plurality of functional blocks. Each functional block includes duplicated components providing duplicated inputs, internal nodes and outputs. The duplicated components are arranged so that when there is a SEU hit to one node and the duplicated node supports the functionalities of the PFD.

Abstract: A phase/frequency comparator is described which includes two edge-triggered storage elements, each set by an edge of a reference frequency signal of a phase—or frequency-locked loop (PLL) and by an edge of an output frequency signal of the PLL. The storage elements are each reset by an output signal of a resetting logic unit, which is activated when both output signals of the storage elements are activated and then deactivated when the output signals are deactivated.

Abstract: A phase-controlled current source for phase-locked loop is provided. The phase-locked loop includes a voltage-controlled oscillator to associate a charging path or discharging path in order to generate an output signal and the output signal is further sensed so as to generate a loop signal. The phase-controlled current source includes a status memory receiving the loop signal and the reference signal so as to output an energy-triggering/energy-removing signal; and a controllable current source, under the control by energy-triggering/energy-removing signal so as to decide whether a charging and discharging action should be performed, wherein after the charging action or discharging action is decided, the charging path or the discharging path is generated through the reference signal and the loop signal.

Abstract: A circuit and method are provided for detecting a phase difference between at least two periodic signals. The circuit and method disclosed herein provide pulsed output signals with wide output pulse widths well suited for use to drive a charge-pump in a phase-locked loop. The wide pulse widths of the output signals generated by the circuit and method allow the charge-pump to sink or source current with higher accuracy and therefore improve the operational characteristics of the phase-locked loop. Further, the circuit and method disclosed herein allow a phase-frequency detector and an associated charge-pump to operate at a higher operational frequency due to the wide pulse widths.

Abstract: Disclosed are a digital phase-frequency detector and a method of operating a digital phase-frequency detector. The detector includes an input circuit, an output circuit and a reset circuit. In use, the input circuit receives first and second input signals during a plurality of cycles, and during a given one of the cycles, generates a first intermediate signal or a second intermediate signal depending on which of the first and second input signals was received first during that given one of said cycles. The output circuit receives these intermediate signals, and outputs, during said one cycle, a first output signal or a second output signal depending on which one of intermediate signals was received by the output circuit during said one cycle. The reset circuit applies a reset signal to the input circuit under defined conditions to begin a new one of said plurality of cycles.

Abstract: A phase frequency detector compares a reference clock signal to a feedback clock signal to generate pulses in one or more output signals. The one or more output signals have a minimum pulse width. The phase frequency detector has a temperature sensing circuit. The phase frequency detector adjusts the minimum pulse width of the one or more output signals using the temperature sensing circuit to compensate for variations in the temperature of the phase frequency detector.

Abstract: A phase frequency detector with two different delays is disclosed herein. The phase detector comprises a first D flip-flop, a second D flip-flop, a first delay unit and a second delay unit. The first D flip-flop receives a reference signal to output an up signal. The second D flip-flop receives a clock signal to output a down signal. The first delay unit delays the received signal with a first delay. The second delay unit delays the received signal with a second delay. When the reference signal synchronizes with the clock signal and the charge pump currents are calibrated, the high-level pulse widths of the up signal and the down signal are determined based on the first delay, and when the reference signal does not synchronize with the clock signal and the charge pump currents are not calibrated, the high-level pulse widths of the up signal and the down signal are determined based on the second delay.

Abstract: The invention relates to a phase-locked loop comprising a voltage controlled oscillator and having a frequency control input for controlling the frequency of the output signal. The phase-locked loop also has a phase comparator for deriving a control signal from a phase error detected in response to a received output signal and a reference signal. The control signal is coupled to the frequency control input of said voltage controlled oscillator. The phase comparator includes a first and a second predefined phase step value to a first accumulated phase value, and the phase comparator has means for determining the phase error. The phase comparator may further have circuit means for performing a first and a second AND operation on the outputs from the first and second accumulators and for obtaining analogue signals corresponding to the outputs of the AND operations. The invention also relates to a method for obtaining information on a phase error between two signals.

Abstract: A phase comparing circuit includes a first storage circuit for reading an external clock signal based on a control clock signal; first and second inverters for inverting a signal from the first storage circuit based respectively on first and second threshold levels; third and fourth inverters for inverting respective signals output from the first and second inverters; a delay circuit for delaying the control clock signal by a specific time; a coincidence control circuit for setting the delayed control clock signal to be active when the signals from the third and fourth inverters coincide with each other, and setting it to be inactive when the signals from the third and fourth inverters do not coincide with each other; and a second storage circuit for reading a signal output form the first storage circuit when the delayed control clock signal is active, and outputting the read signal as the control signal.

Abstract: A circuit for quickly accomplishing highly accurate phase detection using low power is described. The circuit includes a phase decision circuit that receives two clock signals and detects the phase relationship between the two signals by determining which signal was received first. In response, the phase decision circuit generates respective logic signals to reflect the phase relationship determination. The circuit also includes a latch circuit that receives the logic signals from the phase decision circuit and holds the phase relationship determination of the circuit a predetermined time after a predetermined transition of both clock signals have occurred. Methods and systems are also disclosed.

Abstract: Methods, systems and components for use with or as a phase frequency detector. The phase frequency detector stretches its output pulse, allowing the detector to operate in a more linear region. As part of the invention, a new configuration for a D type flip flop is also disclosed. In one embodiment, the D type flip flop triggers at both the rising and the falling edges of the reference input, allowing a lower frequency input to be used while having the advantages of a higher frequency.

Abstract: A DLL circuit of a semiconductor memory apparatus includes a frequency sensing unit that generates and outputs a high frequency signal and a low frequency signal on the basis of a CAS latency signal. A clock dividing unit divides the frequency of an internal clock by a predetermined value and generates a divided clock in response with whether the high frequency signal is enabled or the low frequency signal is enabled. A phase sensing unit that switches a reference clock and a comparison clock, compares the phases thereof in accordance with whether the high frequency signal is enabled or the low frequency signal is enabled, selectively switches first and second phase control signals generated on the basis of the comparison result, and outputs the switched signals.

Abstract: A phase detector detects a phase difference between a first and second signal received by a phase detector. A charge is supplied by a charge pump circuit that corresponds to the phase difference using a phase difference to charge conversion that is substantially linear and nonzero in a phase error region that includes a phase error transition region around a phase error of zero having both negative and positive phase error values. Dual determinations, q1 and q2, offset from each other are made of an appropriate charge for a given phase error between the first and second signals. The charge pump supplies as the total charge pump output a charge value representing a combination of q1 and q2, thereby providing a phase error to charge conversion that is substantially linear in the phase error transition region around zero.

Abstract: A system and method for detecting a phase and a frequency and an arrival-time difference between two signals (118 and 120) that minimizes delay and jitter, and has stable operation even when the two signals (118 and 120) are essentially identical. The system includes two single-ended charge-pump (188), phase-frequency detection (PFD) circuits (280). The first PFD is stable when a reference signal, supplied to a polarity determining flip-flop, leads the signal to be synchronized. A second, complementary, PFD circuit is stable, but has an inverted polarity output, when the signal to be synchronized, supplied to a polarity determining flip-flop, leads the reference signal. A polarity-selection logic-circuit (284) ensures that the first activated PFD controls the polarity a single-ended charge pump (188) for a time-period determined by the delay between the activation of the polarity determining and non-polarity determining flip-flops of the selected PFD.

Abstract: A phase-frequency detector generates output signals at a first and a second output end based on input signals received at a first and a second input end. The phase-frequency detector includes two latch circuits, two pulse generators, two inverting circuits, two sensing devices, and a reset control circuit. The sensing devices control the pulse generators based on signals received at corresponding first ends of the sensing devices. The inverting circuits generate signals to the first and second output ends of the phase-frequency detector based on signals received at corresponding first ends of the inverting circuits. The reset control circuit generates reset signals based on signals received at the first and second output ends of the phase-frequency detector.

Abstract: A circuit for quickly accomplishing highly accurate phase detection using low power is described. The circuit includes a phase decision circuit that receives two clock signals and detects the phase relationship between the two signals by determining which signal was received first. In response, the phase decision circuit generates respective logic signals to reflect the phase relationship determination. The circuit also includes a latch circuit that receives the logic signals from the phase decision circuit and holds the phase relationship determination of the circuit a predetermined time after a predetermined transition of both clock signals have occurred. Methods and systems are also disclosed.

Abstract: A phase-difference detecting method is for detecting phase difference between a first signal and a second signal of the same frequency. First, generate a detection signal. Next, sample the detection signal respectively according to the first signal and the second signal to obtain a first sample value and a second sample value. Then, determine whether a determination condition that the first and the second sample values are respectively equal to the previous first and second sample values is satisfied. When the determination condition is unsatisfied for the first time, record a delay time of the detection signal as a first time. When the determination condition is unsatisfied for the second time, record a delay time of the detection signal as a second time. Obtain the phase difference between the first signal and the second signal according to the first time and the second time.

Abstract: A phase detector includes a first clock driver comprising a first LC tank. The first clock driver provides a strobe to a plurality of flip-flops associated with sampled data being received by the phase detector. The second clock driver includes a second LC tank. The second clock driver provides a strobe to a plurality of flip-flops associated with sampling the phase error of the phase detector. The first and second LC tanks have different adjustable center frequencies and experience a programmable delay between the outputs of the first and second clock drivers so as to determine the data sampling phase of the phase detector.

Abstract: A phase frequency detector includes a phase error detector outputting a phase error signal according to a first input signal and a second input signal; a phase error judgment unit outputting a phase error judgment signal according to the first input signal and the second input signal; and a reset unit outputting a first reset signal to reset the phase error detector, and outputting a second reset signal to reset the phase error judgment unit, according to the phase error judgment signal.