Abstract: A slave clock generation system and method suitable for use with synchronous telecommunications networks generates one or more slave clocks from a selected reference clock using a direct digital synthesis technique. A multiplexer selects a reference clock from a number of available sources, each of which can be at its own spot frequency, based on a predetermined selection order. Toggle detectors monitor each of the available clock sources, and block the selection of any that are not within a specified frequency range. A local oscillator establishes short-term and long-term measurement periods; the cycles of the selected reference clock are counted over consecutive short-term measurement periods to determine the relative frequency of the selected clock with respect to the frequency of the local oscillator. The cycle counts are fed to a phase-to-clock converter, which produces a slave clock output having a frequency that varies with the relative frequency measured for the selected clock.

Abstract: The phase of a pulsed test signal is measured with reference to a reference signal of constant frequency by sampling the test signal at times determined by transitions in the reference signal and comparing the sampled test signal with the output of a phase accumulator clocked by the reference signal. A resulting measurement signal represents a difference in the number of transitions occurring in the sampled test signal and a reference state signal output by the phase accumulator. The measurement signal may be averaged and integrated to obtain an error signal which may then be filtered to provide a control signal for an oscillator. A digital frequency synthesizer is provided by frequency dividing the output of the oscillator by a constant multiple to obtain the test signal and integrating an offset signal in addition to the averaged measurement signal so that the operating frequency of the oscillator is offset from a nominal frequency by an amount determined by the offset signal.

Abstract: A phase detector circuit comprising a control circuit, a pump-up circuit and a pump-down circuit. The control circuit may be configured to generate a control signal in response to (i) a data signal, (ii) a half-rate clock signal, and (iii) a quadrature of the half-rate clock signal. The pump-up circuit may be configured to generate a pump-up signal in response to (i) the data signal, and (ii) the control signal. The pump-down circuit may be configured to generate a pump-down signal in response to (i) the pump-up signal and (ii) the control signal.

Abstract: A wireless communication system (10) uses a phase detector (28) having a first pair of flip-flops (50, 56) for detecting the phase difference between an input frequency and a reference frequency. The first pair of flip-flops control current sources (66, 70) in the charge pump of the phase detector to modulate the error signal. A second pair of flip-flops (52, 58) detect when the input frequency is more than 2.pi. ahead of or behind the reference frequency. The second pair of flip-flops increment and decrement a counter (54) which in turn controls additional current sources (78-88) in the charge pump. The additional current sources extend the linear operating range of the error signal when the phase error exceeds .+-.2.pi..

Abstract: The present invention, generally speaking, provides improved methods of generating clean, precisely-modulated waveforms, at least partly using digital techniques. In accordance with one aspect of the invention, a "difference engine" is provided that produces a digital signal representing the frequency error between a numeric frequency and an analog frequency. The frequency error may be digitally integrated to produce a digital signal representing the phase error. The difference engine may be incorporated into a PLL, where the analog frequency is that of an output signal of a VCO of the PLL. Direct modulation of the PLL output signal may be performed numerically. By further providing an auxiliary modulation path and performing calibration between the direct modulation path and the auxiliary modulation path, modulation characteristics may be separated from loop bandwidth constraints.

Abstract: A clock signal phase comparator includes a first delay unit for delaying a clock signal for a predetermined time, a first phase detector for comparing an output signal of the first delay unit and a reference clock signal and outputting a first high or low level output signal, a second delay unit for delaying for a predetermined time and outputting the reference clock signal, and a second phase detector for comparing an output signal of the second delay unit and the clock signal and outputting a second high or low level output signal. The phase comparator separately displays the phase comparison results in grades of fast, slow and locking, and when a locked phase is detected, the phase control system is partially or entirely disabled, for thereby reducing current consumption of the system.

Abstract: A phase detector circuit comprising a pump-up circuit and a pump-down circuit. The pump-up circuit may be configured to generate a pump-up signal in response to (i) a data signal, (ii) a half-rate clock signal and (iii) a quadrature of the half-rate clock signal. The pump-down circuit may be configured to generate a pump-down signal in response to (i) the pump-up signal and (ii) the quadrature of the half-rate clock signal.

Abstract: The invention relates to a phase detector, especially for a Phase Locked Loop of a desynchronizer of a digital transmission system for the transmission of signals of the synchronous digital hierarchy with a difference former (subtractor) connected to a comparator, to which can be conducted at the input side, via a first accumulator, a first input signal, and via a second accumulator a second input signal with the comparator being connected at the output side via a coder to a control input of the second accumulator.

Abstract: A sampling circuit system enhances sampling resolution without increasing frequencies of clock signals for sampling. An input waveform is input to a first group of sampling circuits and a sampling circuit serving as a standard circuit. Clock signals out of phase from each other by 2 .pi./n (n=an integer not less than 3) radian, respectively, against a clock signal input to the standard circuit are input to the first group of sampling circuits for sampling. Then sampling signals output from the first group of the sampling circuits are input to a second group of sampling circuits so as to be sampled again by inputting a sampling signal output from the standard circuit as a common clock signal for the second group of sampling circuits.

Abstract: A circuit comprising a pump-up circuit and a pump-down circuit. The pump-up circuit may be configured to generate a pump-up signal in response to (i) a data signal and a clock signal. The pump-down circuit may be configured to generate a pump-down signal in response to (i) the data signal, (ii) the clock signal, and (iii) a quadrature of the clock signal. The pump-down circuit and the pump-up circuit are generally independent circuits.

Abstract: Disclosed are a phase detector for detecting the phase difference between a data signal and a clock signal, and a timing extracting circuit for controlling the phase of the clock signal so that the phase relationship between the clock signal and the data signal is optimal by using the phase detector. The phase detector includes an edge detector for generating an edge signal at the rising edge and the falling edge of the data signal, and a D flip flop (D-FF) for storing and outputting the logical value of the clock signal at the time of generation of the edge signal, and holding the logical value until the generation of the next edge signal, thereby outputting a signal corresponding to the phase difference between the data signal and the clock signal. A clock generator in the timing extracting circuit having a PLL structure controls the phase of the clock signal so that the difference becomes optimal.

Abstract: A variable delay circuit includes a first gate having a first delay amount, and a second gate having a second delay amount greater than the first delay amount. A difference between the first delay amount and the second delay time is less than the first delay amount.

Abstract: A digital phase acquisition clock recovery circuit includes a digital phase-locked loop that employs a truth table decoder to set the actual delay through a plurality of individual delay elements to generate a plurality of clock phase signals approximately equally spaced in time over one reference clock cycle, and a data sampler circuit that generates a plurality of received data samples from an incoming data sample taken at the rising edge of the respective clock phase signals and synchronizes the data samples to reference clock on a bit period-by-bit period basis. A digital phase acquisition circuit includes an edge detector which evaluates the data samples over each bit period to detect the location of a transition between respective adjacent samples, wherein logic is employed to continually determine the "relative quality" of each data sample, based upon its sampling time being furthest from a detected edge transition.

Abstract: An improved phase detector for detecting the difference between an information signal and a clock signal is provided. The information signal is divided into a plurality of N divided signals, the data rate of each divided signal being the data rate of the information signal divided by N. A plurality of N variable width difference pulse signals are generated each being responsive to the phase difference between a divided signal and the clock signal. One or more fixed width reference pulse signals having a width proportional to one-half clock period are also generated. A phase error signal is then provided in response to the N difference pulse signals and the one or more reference pulse signals. Preferably, N is equal to 2.sup.M, where M is a positive integer greater than or equal to one.

Abstract: A parallel sampling phase detector with linear output response is disclosed. The parallel sampling phase detector for use in data recovery. The device includes a voltage controlled oscillator (VCO) that generates ten separate phase signals using a five stage ring oscillator. Five linear phase detectors are employed in the device, each operating during one of five "window" intervals. The "window" intervals are non-overlapping, and are generated using preselected ones of the VCO output phases. The linear phase detectors each generate, respectively, a variable pulsewidth pump up signal wherein the pulsewidth of the pump up signal is proportional to a phase difference between the input data signal applied to the phase detector, and the output phase signals of the VCO. Each phase detector also generates a pump down signal that has a fixed pulsewidth.

Abstract: A frequency shift detection circuit for detecting a frequency shift between a first signal and a second signal includes two or more delay circuits coupled to one another in series and two or more comparison logic circuits. The first delay circuit in the series receives one of the first and second signals and produces a delayed replica. Each of the other delay circuits receives the delayed replica produced by the previous delay circuit in the series and produces a further delayed replica. Thus, the signal produced by each delay circuit is delayed from the original signal by a different amount. Each comparison logic circuit receives one of the delayed replicas and receives the other one of the first and second signals, i.e., the one that is not received by the delay circuits. In response, the comparison logic circuit produces a frequency shift detection signal when it detects a phase difference between that other one of said first and second signals and the delayed replica.

Abstract: An integrated XNOR flip-flop is provided which is faster than conventional XNOR flip-flop combinations. The integrated XNOR flip-flop is faster and uses less area than conventional XNOR flip-flop combinations. The integrated circuit has few gates along the critical path and takes advantage of the set up times inherent in the flip-flop. Accordingly, the integrated XNOR flip-flop is able to perform the same function in an expedient manner. In one illustrative embodiment, a plurality of the integrated XNOR flip-flops are used to compare a tag of a cache memory with an address to determine whether the desired address is available in the cache.

Abstract: A phase/frequency detector, such as may be used in a phase-lock loop (PLL), having reduced jitter at high frequencies by reducing or eliminating the dead zone. The detector generates two output signals (UP and DOWN) wherein one of the output signals (depending upon which input signal arrives first) has a pulse width which is equal to a time delay between the input signals. There is a dead zone associated with very small phase differences between the input signals, and the dead zone is reduced by increasing the durations of two output pulses, using several delay elements which operate on signals that are derived from the reference and feedback inputs. The circuit may be tuned to reduce the dead zone to less than one picosecond, making it particularly useful for very high speed (greater than one gigahertz) clock circuits. The phase/frequency detector uses self-resetting, complementary metal-oxide semiconducting (SRCMOS) gates.

Abstract: A phase detector produces a pulsed tri-state output signal representing a phase difference between first and second input signals. The pulse width of the output signal indicates the magnitude of the phase difference while the sign of the output signal pulses indicates whether the first input signal leads or lags the second input signal. The first and second input signals drive D and clock inputs, respectively, of a type D flip-flop, and also drive separate inputs of an XOR gate. An output of the flip-flop provides a signal input to a tristate buffer while an output of the XOR gate drives a tri-state control input of the tristate buffer. The tristate buffer produces the phase detector output signal.

Abstract: A phase-frequency detector provides a decreased blind spot near 360.degree. of phase error and a resulting increased phase error detection range. In one embodiment, the phase-frequency detector includes two latches that are set in response to the detection of positive transitions in respective input clock signals. A reset controller resets both latches when they both get set. The duration and sequence of the latch states are thereby indicative of phase errors between the input clock signals. Two edge-triggered pulse generators provide a sustained indication of a detected positive transition in the respective input clock signals. When the time duration of the sustained indications is set equal to the reset time required by the latches and reset controller, the blind spot of the phase-frequency detector is largely eliminated.

Abstract: A system (100) for distributing a clock signal to many points on an integrated circuit. The system includes using a delay lock loop with specific digital circuits to accomplish the phase error detection and delay element selection. In one embodiment, two flip-flops are used to detect a phase error. In another embodiment, both macro (202) and micro phase detectors (218) are used and the delay element selection is performed in two stages by using a shift register (210) in a first stage and a counter (220) in a second stage. Another feature of the present invention is, the ability to distribute the reference clock or a synchronized clock to different portions of the circuitry on an integrated circuit. Multiple clock distribution systems are provided which may be selected.

Abstract: Briefly, in accordance with one embodiment of the invention, an integrated circuit includes: a phase frequency detector (PFD) including two clock input ports, an up signal output port, and a down signal output port. The PFD includes digital circuitry including transistors coupled in a configuration to adjust an amount of overlap of an up signal and a down signal based, at least in part, upon the magnitude of an amount of phase delay between two clock signals respectively applied to the PFD input ports. Briefly, in accordance with another embodiment of the invention, an integrated circuit includes: a phase frequency detector (PFD) including two clock input ports, an up signal output port, and a down signal output port.

Abstract: A phase error signal generator including a phase comparator for comparing phases of two input pulse signals, change over the output polarity according to phase lead and lag between said input pulse signals, and output an electric charge proportional to a time difference between said input pulse signals, an alternating front stage capacitor for charging an electric charge according to said time difference, a base-grounded transistor of which emitter is coupled to said front stage capacitor, a rear stage capacitor coupled to the collector of said transistor, and a switch controller for biasing said transistor until the next edges arrive after detecting the edges corresponding to said two input pulse signals, wherein an integrating voltages of phase error of said two input pulse signals is obtained from said rear stage capacitor by transferring the electric charge proportional to the time difference information of each edge of the input pulse signal generated in said front stage capacitor in order.

Abstract: A PLL circuit is disclosed which can achieve a locked state in a short time. The PLL circuit has a phase comparator, a loop filter and a voltage controlled oscillator. The phase comparator is provided with frequency adjusting (or matching) circuits that are operative to charge the loop filter when it is detected that an oscillation frequency of the voltage controlled oscillator is lower than a frequency of an input signal, so as to increase the oscillation frequency of the voltage controlled oscillator, until it is detected that an oscillation frequency of the voltage controlled oscillator is higher than the frequency of the input signal.

Abstract: A lock detector (16) includes a set circuit (64), a reset circuit (120), and a latch circuit (80). The latch circuit (80) provides an output signal (82) in response to the temporal relationship of the first input signal (12) and the second input signal (14). The set circuit (64) initiates the transition of the latch circuit (80) to the locked state, while the reset circuit (120) initiates the transition of the latch circuit (80) to the not-locked state.

Abstract: A method of performing phase-frequency comparison comprising the steps of receiving first and second clock signals; comparing the signals by triggering flip-flop circuits controlled by AND gates, and providing a first output when first signal is in advance of the second signal, and a second output when second signal is advance of the first signal.

Abstract: A phase detection apparatus produces a phase difference signal in response to the phase difference between two applied input signals. The phase detector includes a lead/lag indicator receiving the input signals, and a logic block receiving the input signals. The logic block generates an output signal in response to the time delay between corresponding amplitude transitions, such as rising edges, of each of the input signals. The lead/lag indicator records which one of the two input signals leads in phase and generates an enable signal that steers the output signal from the logic block to one or the other of the phase detector's two output terminals.

Abstract: A phase lock loop circuit includes a phase detector for receiving a reference clock and a feedback clock, a charge pump for receiving a Down pulse and an Up pulse from the phase detector, a loop filter for being charged and discharged by the output from the charge pump, and a voltage controlled oscillator for outputting a frequency signal according to the output voltage of the loop filter, the phase detector including a power cut input terminal, and when a power cut signal is input to the power cut input terminal, a Down pulse and an Up pulse output from the phase detector are forcibly changed to logic "L" level and logic "H" level, respectively, which reduces the power consumption in the phase locked loop circuit.

Abstract: A parallel sampling phase detector with linear output response is disclosed. The parallel sampling phase detector is disclosed for use in data recovery. The device includes a voltage controlled oscillator (VCO) that generates ten separate phase signals using a five stage ring oscillator. Five linear phase detectors are employed in the device, each operating during one of five "window" intervals. The "window" intervals are non-overlapping, and are generated using preselected ones of the VCO output phases. The linear phase detectors each generate, respectively, a variable pulsewidth pump up signal wherein the pulsewidth of the pump up signal is proportional to a phase difference between the input data signal applied to the phase detector, and the output phase signals of the VCO. Each phase detector also generates a pump down signal that has a fixed pulsewidth.

Abstract: A phase detector enables sampling of an input waveform such that a resolution, equivalent to the resolution conventionally obtained by doubling a clock frequency, is obtained without doubling the frequency. In order to accomplish this, the phase detector has the following construction and function. A first sampling circuit samples an input waveform using an in-phase clock signal from a clock to generate a sampled waveform. A second sampling circuit samples the input waveform by using a falling edge of the clock to generate an output a signal. A third sampling circuit samples the output signal from the second sampling circuit by a rising edge of the sampled waveform supplied from the first sampling circuit to generate a phase detection flag. This phase detection flag thus detects the presence of the input waveform at a rate double the frequency of the clock.

Abstract: A phase detector circuit receives both a reference clock signal and a sense clock signal and produces a synchronization signal if the sense and reference clock signals are in phase within a specified tolerance. A lead/lag signal is provided to a skew control circuit and accompanying delay circuits to increase or decrease the amount of delay on the reference clock signal and the sense clock signal if the two signals are not in phase within the specified tolerance. The sense clock signal is a feedback signal returned from logic circuitry, which originally receives the reference clock signal, which may be supplied by a master clock signal within a processor.

Abstract: The present invention is directed to providing a phase detector capable of establishing phase-locked-loop operation in a highly accurate and reliable manner. For example, exemplary embodiments detect a phase difference between at least two input signals to phase lock the input signals to one another. Exemplary embodiments include two phase detectors each of which receives the two input signals (e.g., three-state phase detectors), and each of which is forced to operate outside of its dead-band region by introducing predetermined phase delays for its inputs. Each of the two phase detectors detects a phase difference between its respective inputs. The two phase differences are then combined to produce a composite output signal formed as a net charge proportional to the net phase difference detected by the two phase detectors.

Abstract: A phase lock detector circuit is disclosed that generates delayed versions of both a reference clock signal and a synthesized clock signal. From the delayed signals, first and second control signals that are pulses are generated. The pulses are passed through respective delays of predetermined durations and then clocked into respective shift registers by the latched signal of the opposite input. The shift register outputs are logically combined and shifted into a third shift register. Outputs from the third shift register are logically combined to ascertain whether a phase-lock loop is phase lock. The lock detector circuit may include a lock-out circuit to disable the phase lock detector circuit upon detecting phase lock.

Abstract: A circuit configuration for measuring a phase difference between a reference signal and a clock signal includes a first shift register being clocked by the clock signal and having an input receiving the reference signal. A digital differentiator is connected downstream of the first shift register and has an output. A counter has an input receiving the clock signal and an output outputting a multidigit binary word. A buffer memory is connected to the counter and to the digital differentiator for storing the binary word at the output of the counter in memory upon an appearance of a corresponding output signal of the digital differentiator. The buffer memory has an output forming most significant bits of an output binary word. A second shift register is inversely clocked by the clock signal and has an input receiving the reference signal and an output. An analog differentiator has an input connected to the output of the digital differentiator and an output.

Abstract: A method of phase synchronization of a bit rate clock signal generated on a receiver side with a biphase-modulated digital RDS signal that is demodulated on the receiver side with both signals having the same bit rate. The bits of both the RDS signal and the bit rate clock signal are each composed of two half bits having different digital potential values. The first or the second RDS half bit has a high digital value and the other RDS half bit has a low digital value based on which one of two logic values "1" and "0" is represented by the respective RDS bit. At a first time coinciding with the time of a rising and/or falling edge of a bit of the RDS signal, the digital value of the bit rate clock signal is measured as a first sample value, and at a second time shifted from the first time by a delay time that is shorter than a half bit duration, the digital value of the bit rate clock signal is measured as a second sample value.

Abstract: A PLL including a phase comparator, a VCO, and a charge pump further includes a reset circuit. The reset circuit detects whether both of the charge pump transistors are in an ON state, and if so, generates a reset signal which inhibits the UP and DOWN signals generated by the phase comparator. The reset circuit includes first and second detection circuits and a signal generating circuit.

Abstract: A phase-frequency detector (12) is configured for operating at a high frequency. A transition of a clock signal (REF CLK) is detected by a first latch (52) and a signal UP is generated. A transition of a feedback signal (FBK) is detected by a second latch (56) and a signal DOWN is generated. An logic circuit (64) detects the signals UP and the DOWN and generates a reset signal (RESET). A pulse-width of the reset signal (RESET) is controlled and limited by the logic circuit (64) to provide a faster response time for setting the first and second latches (52 and 56) to a state that allows detection of the phase and frequency differences between the clock signal (REF CLK) and the feedback signal (FBK).

Abstract: A phase detector provides a digital output having a linear relationship to the phase difference between a reference signal and an applied input signal. The phase detector counts the number of cycles of the reference signal within a time interval determined by the difference in arrival times of corresponding amplitude transitions of the reference signal and the input signal. A digital output representing the number of counted cycles is produced. A dither generator adds random time variation to the time interval over which the reference signal cycles are counted to introduce a corresponding random variation in the digital output.

Abstract: A symmetric capture range is produced in a two-quadrant phase detector phase locked loop that utilizes nonsymmetric pulse waves. The phase detector is enabled only during VCO pulses. A latch stores the relative relationship between the leading edge of the input pulse and the center of the VCO pulse in the previous cycle. If the phase angle .theta. form the VCO pulse center to the leading edge of the input pulse is0 deg<.theta.<180 deg,then the phase detector incrementally decreases the VCO frequency at the next VCO pulse. If the phase angle .theta. is180 deg<.theta.<360 deg,then the phase detector incrementally increases the VCO frequency at the next VCO pulse.

Abstract: A phase detector is disclosed that eliminates frequency ripple in a phase-locked loop circuit. The detector includes first and second circuits for providing UP and DOWN signals respectively. It also includes a delay element for setting the duration of the DOWN signal so as to eliminate phase jitter and static phase offset.

Abstract: A phase-frequency detector for a phase-locked loop (PLL) circuit has symmetrical phase detection characteristics and produces symmetrical activation times on the "up" and "down" outputs for connection to a PLL charge pump circuit. The symmetrical characteristics are accomplished by using RS latch circuits at the outputs of the phase-frequency detector to provide the same loads and the same propagation delay for both the "up" and the "down" outputs. In addition, cross-wired sequential gates are used for at least some of the gates in the logic gate array of the detector to produce the same propagation delays in the gates.

Abstract: The digital phase detector detects a phase shift between a comparison clock pulse signal (VT) and a reference clock pulse signal (RT). It includes logic gates (STO,STA) for generating start and stop pulses from respective successive pulses of the comparison and reference clock pulse signals (RT,VT). A counter (ZG,Z) counts the pulses of a counter clock pulse signal (ZT) of a higher frequency in a time window between the start signal and the subsequent stop signal. The counter value of the counter is a measure of the phase shift between the comparison and reference clock pulse signals (VT,RT). Quantization errors in the phase shift signal are considerably reduced by providing a logical gate (VZ) for determining the sign of the phase shift and a device (.mu.P) for adding a constant, advantageously 0.5, to the counter value.

Abstract: A phase lock loop includes a charge pump, a voltage controlled oscillator (VCO), and a phase frequency detector. The phase frequency detector has a dynamic logic structure. The phase frequency detector generates up and down signals for directing the charge pump to provide a voltage signal to the VCO to vary the frequency of the VCO clock. The difference between the up and down signals is indicative of the phase difference between the reference clock signal and the VCO clock. The phase frequency detector includes up and down signal generators for generating the up and down signals, respectively. The up signal generator includes a first p field effect transistor (FET) having a gate for receiving a set signal, a second p FET having a source coupled to the drain of the first p FET and having a gate for receiving a reference clock signal. A first n FET has a source coupled to the drain of the second p FET and has a gate for receiving the set signal.

Abstract: A phase detection signal is generated with a phase detection logic pipeline and its associated tapped pipeline signal combinational logic circuit. The phase detection logic pipeline generates phase detection logic pipeline output signals from a first input clock signal and a second input clock signal. The first input clock signal is applied to a first flip-flop of a set of serially connected flip-flops to generate a pipeline signal. The pipeline signal is driven through the set of serially connected flip-flops by the second clock input signal. Logic pipeline output nodes connected between the serially connected flip-flops carry the phase detection logic pipeline output signals. The phase detection logic pipeline output signals are applied to the tapped pipeline signal combinational logic circuit, which logically combines the signals to generate the phase detection signal.

Abstract: A phase comparator has a first comparing circuit and a second comparing circuit. The first comparing circuit produces a first output pulse having a duration equal to a phase lead of a first input signal with respect to a phase of a second input signal. The first phase comparator also produces a second output pulse equal in duration to a phase lag of the first input signal with respect to the phase of the second input signal. The second comparing circuit produces a third pulse equal in duration to a phase lead of a third input signal with respect to a phase of a fourth input signal. The second comparator also produces a fourth output pulse equal in duration to a phase lag of the third input signal with respect to the phase of the fourth input signal.

Abstract: A reset signal generating circuit included in a phase comparator of a PLL circuit includes fourth and second transistors having their respective gates connected to the gates of first and third transistors in a crossed form. A reset signal is output through first and third transistors and through fourth and second transistors in response to output of signals UP and DOWN. Accordingly, the time period between the output of signals UP, DOWN, and the output of the reset signal is made constant regardless of which of the signals UP and DOWN has been output first.

Abstract: A phase detector for a phase-locked loop ("PLL") circuit under control of a local oscillating clock ("LOSC") signal and a method of operation thereof.

Abstract: Jitter attenuators (100) with a phase detector (104) to control a crystal oscillator to remove jitter wherein the phase detector includes both a sequential phase/frequency detector (200) of low transistor count and an arrangement of two sequential phase/frequency detectors (198 and 200) to increase gain and two drivers for the crystal oscillator.

Abstract: A single-edge triggered phase detector which provides high speed phase detection. The phase detector works on only a single edge of the clock and data signal, which can be either the rising or falling edge. Extracted control signals are latched for at least one half of a clock period or more to ensure full rail to rail swing.

Abstract: An integrated circuit utilizing a symmetric phase detection circuit for detecting a phase relationship between a reference clock signal and a delayed clock signal. The integrated circuit described herein features a control block circuit coupled to receive the reference clock signal and an enable check signal. The control block circuit generates an enable signal which provides the present invention with the ability to detect the phase difference between signals having the same frequency or signals that differ in frequency by a rational factor. The control block circuit generates the enable signal in response to the enable check signal and the reference clock signal. The enable signal, the reference clock signal, and the delayed clock signal are coupled to the phase detection circuit. In response to the enable signal, the phase detection circuit then determines the phase relationship between the reference clock signal and delayed clock signal.