Abstract: Systems and methods for synchronizing a system clock signal with a reference clock signal having a reduced phased offset to improve operating speeds of integrated circuits. This is accomplished by generating delayed system and reference clock signals by using the system and reference clock signals. The generated delayed clock signals are then monitored to determine the arrival of the raising and falling edges of the delayed clock signals. The system clock signal is then compensated based on the determination of the arrival of the delayed clock signals to substantially synchronize the system clock signal with respect to the reference clock signal.

Abstract: Simple, glitch-free phase detector circuits provide add and subtract output signals indicating the phase relationship between two input clock signals. Some embodiments also provide a lock output signal having a lock window, and in some of these embodiments, the size of the lock window is programmable. An optionally delayed version of the feedback clock signal is stored a first time when the input clock signal goes high, then stored a second time after a predetermined delay. In some embodiments, the predetermined delay is programmable. When both stored values are low, the subtract output signal is active. When the first stored value is high, the add output signal is active, regardless of the state of the second stored value. When the first stored value is low and the second stored value is high, the two clocks are synchronized and the phase detector indicates a lock condition.

Abstract: A phase detector for a delay locked loop with a delay unit that delays a periodic clock signal by a settable delay, has a first input for the periodic clock signal, a second input for the delayed clock signal, an UP output and a DOWN output. The phase detector outputs a first pulse signal at the UP output and a second pulse signal at the DOWN output, which signals can respectively assume a first or a second level, for the setting of the delay unit. The first pulse signal changes to the first level in the event of a positive edge of the clock signal and the second pulse signal changes to the first level in the event of a positive edge of the delayed clock signal. In the event that both pulse signals are at the first level, a reset device resets both pulse signals to the second level.

Abstract: A linear phase detector includes first, second and third latches connected in series, each of the latches having a data input, a data output and a clock input, and further includes reference signal generation circuitry and error signal generation circuitry. The reference signal generation circuitry has at least a first input coupled to the data output of the second latch and a second input coupled to the data output of the third latch. The error signal generation circuitry has at least a first input coupled to the data input of the first latch and a second input coupled to the data output of the second latch, and is configured to generate an output that is indicative, relative to the reference signal, of the phase error of a clock signal.

Abstract: A digital phase detector with a master stage having imbalanced latching devices with intentional input-referred offset for determining which one of a pair of input signals is leading the other and a slave stage connected to the master stage imbalanced latching devices and which slave stage is transparent when ones of the master state imbalanced latching devices are set to a logical one and which is latched and held when the master state latching devices are reset and armed for the next phase measurement.

Abstract: A phase detector employing asynchronous level-mode sequential circuitry is described. The phase detector includes edge detection circuitry for generating a first edge detection signal and a second edge detection signal. The first edge detection signal is indicative of an edge in a first clock signal, and the second edge detection signal is indicative of an edge in a second clock signal. The phase detector further includes a state machine that is asynchronously responsive to level changes in the first and second edge signals. The state machine generates a control signal indicative of which of the first and second clock signals is leading the other of the first and second clock signals.

Abstract: Briefly, in accordance with one embodiment, an integrated circuit includes a phase-frequency detector (PFD) including two clock input ports, an up signal port and a down signal port. The PFD includes digital circuitry including transistors coupled in a configuration to adjust an amount of overlap of an up output signal pulse and a down output signal pulse based, at least in part, upon the magnitude of an amount of phase delay between two respective clock signal pulses applied to the two input ports. Of course, additional embodiments are also disclosed.

Abstract: The phase comparator in a phase locked loop synthesizer has a identical first and second transmission gates connected to a front row and a back row of 2N−1 gate delay elements, respectively. Third and fourth transmission gates are permanently set to an ON setting. The first transmission gate and NAND gates operate as a gate delay element when a COUNT signal is at a low logical level and operate as a ring oscillator when the COUNT signal is at a high logical level.

Abstract: A frequency comparator detects the phase of a data signal DATA by using four-phase clocks ICLK, /ICLK, QCLK and /QCLK as a reference and detects a change in the phase. A counting processing unit counts a period in which a control signal UP2 or DN2 is activated within a predetermined period, and outputs an overflow detection signal LOL2 if the frequency is high. A hysteresis generating unit changes a signal LOL to the L level only after signal LOL goes low X times consecutively. On the other hand, after signal LOL is set to the L level once, the hysteresis generating unit changes signal LOL to the H level only after signal LOL2 goes high X times consecutively. With such a configuration, a phase-locked state detecting circuit with reduced malfunction even when a data signal having larger jitter is input can be provided.

Abstract: Improved systems and methods of phase detecting are described. In one aspect, a phase detector includes a latch having an input stage and an output stage. The input stage couples to the output stage through a dynamic storage node and includes a discharge circuit. The discharge circuit has a first input and a second input and defines a discharge path for discharging the dynamic storage node that is substantially symmetric with respect to the first and second inputs. In another aspect, the dynamic storage node is discharged with a characteristic discharge time in response to a transition of the first input from a low logic level to a high logic level when the second input is at a high logic level. The dynamic storage node also is discharged with substantially the same characteristic discharge time in response to a transition of the second input from a low logic level to a high logic level when the first input is at a high logic level.

Abstract: A phase detector system and method operate correctly, regardless of the point of time at which the operation of the delay locked loop is initialized with respect to the phases of reference and feedback clock signals. The system comprises a phase detector for a delay-locked loop for compensating for a difference in phase between a first clock signal and a second clock signal. The phase detector includes a first flip-flop receiving the first clock signal and generating a first output signal, the first flip-flop being reset by a first reset signal. A second flip-flop receives the reference clock signal and generates a second output signal, the second flip-flop being reset by a second reset signal, the first and second reset signals being sourced by separate logic paths.

Abstract: A phase detection system allows the capture range, lock range and jitter tolerance to be extended beyond ±360°. The capture range for the phase detection system may be extended in programmable amounts up to several thousand clock cycles or can be set to any desired maximum capture range in steps of approximately 360°. The phase detection system circuit utilizes a coarse phase detector and a fine phase detector. The phase detection system uses the digital cycle slip counter phase detector to provide a wide phase capture and lock range for a large jitter tolerance. The phase detection system combines this detector with a fine phase measurement from a PFD (phase and frequency detector) for very accurate phase control and low output jitter. The PFD operates in the approximately ±540° range and provides overlap in response with a coarse phase detector using a digital cycle counter approach.

Abstract: A phase-frequency detector (PFD) with increased phase error gain during acquisition of phase lock when used in a phase-locked loop (PLL). The reference and feedback signals are time-multiplexed into N pairs of input signals. Each pair of input signals is detected by one of N phase-frequency detectors, which produce N pairs of detection signals indicative of phase differences between the reference and feedback signals. These N pairs of detection signals are combined in separate logical-OR operations to produce a frequency increase control signal and a frequency decrease control signal indicative of when the feedback signal frequency is lower and higher, respectively, than the reference signal frequency.

Abstract: A high speed phase detector utilizes an integrated XOR/SUMMER/MUX circuit having a higher bandwidth and lower power than conventional designs. The XOR/SUMMER/MUX circuit combines the functionality of two parallel XOR devices in series with a summer/multiplexer in a manner that reduces the number of gate delays associated with the input signals. In a practical implementation, the XOR/SUMMER/MUX circuit includes XOR arrangements having a plurality of transistors implemented at a first transistor level and a plurality of transistors implemented at a second transistor level. The XOR/SUMMER/MUX circuit also includes transistors implemented at a third transistor level; these transistors are utilized by the multiplexer feature of the circuit.

Abstract: While generating a correction pulse (E) based on a clock signal (Xck1) input into one input terminal (6), a frequency and a phase of a differentiated pulse train (Data_Dif) input into the other input terminal (5) are compared with a frequency and a phase of the clock signal input into the one input terminal, then a leading phase instructing pulse (U4) and an incomplete lagging phase instructing pulse (D4a) are generated based on this compared result, then false pulses contained in the incomplete lagging phase instructing pulse (d4a) are removed by using the correction pulse (E) when the differentiated pulse train (Data_Dif) input into the other input terminal is in the tooth missing state, and then the precise leading phase instructing pulse (U4) and the precise lagging phase instructing pulse (D4) are output from two output terminals (7, 8).

Abstract: A microcomputer has an internal reset signal generator for generating an internal reset signal from an external reset signal supplied via a chip reset input terminal. The internal reset signal generator includes a first two-input logic circuit that has its first gate input terminal connected to the chip reset input terminal and outputs a low-level first logic signal only when its two gate input terminals are placed at a high level. The first logic signal is inverted by an inverter and is supplied to the second gate input terminal of the first two-input logic circuit. The second gate input terminal is pulled up by a capacitor connected to a higher power supply voltage terminal. The external reset signal and the first logic signal are supplied to a second two-input logic circuit that changes the level of the reset signal only when both the inputs are at the high level.

Abstract: A phase detection system allows the capture range, lock range and jitter tolerance to be extended beyond ±360°. The capture range for the phase detection system may be extended in programmable amounts up to several thousand clock cycles or can be set to any desired maximum capture range in steps of approximately 360°. The phase detection system circuit utilizes a coarse phase detector and a fine phase detector. The phase detection system uses the digital cycle slip counter phase detector to provide a wide phase capture and lock range for a large jitter tolerance. The phase detection system combines this detector with a fine phase measurement from a PFD (phase and frequency detector) for very accurate phase control and low output jitter. The PFD operates in the approximately ±540° range and provides overlap in response with a coarse phase detector using a digital cycle counter approach.

Abstract: A method and circuit for determining variation between an input clock signal (CLK0) and a reference clock signal (REFCLK) is provided. A plurality of time shifted input clock signals (CLK0, CLK1, . . . , CLK09) can be generated from a single input clock signal (CLK0). The plurality of time shifted input clock signals (CLK0, CLK1, . . . , CLK09) can be sampled at successive periodic intervals occurring relative to the reference clock signal (REFCLK). For each of the time shifted input clock signals (CLK0, CLK1, . . . , CLK09), a sampled value for a succeeding and a preceding periodic interval can be compared to determine whether there is a variation between an input clock signal (CLK0) and a reference clock signal (REFCLK).

Abstract: A phase frequency detector (PFD) circuit (516) compares two clock signals and generates a number of outputs to indicate a phase difference between these two clock signals (513, 519). The phase frequency detector has more than three states. The PFD circuit may be used in phase locked loop (PLL) or delay locked loop (DLL) circuit in order to maintain or lock a phase relationship between the two clock signals. The PFD circuitry will allow for a fast lock acquisition time, even when there is a relatively wide frequency range between the two clock signals.

Abstract: An apparatus comprising a first circuit and a second circuit. The first circuit may be configured to generate (i) a first intermediate signal in response to a first differential signal and (ii) a second intermediate signal in response to a second differential signal. The second circuit may be configured (i) to generate one or more output signals in response to a relative arrival time of the first and second intermediate signals and (ii) to clamp a later arriving one of the first and second intermediate signals to a predefined voltage level.

Abstract: A non-linear phase detector includes a retiming stage and a phase synchronization stage. The retiming stage is coupled to a data signal and a recovered clock signal. The retiming stage is triggered by the recovered clock signal and samples the data signal to generate a retimed data signal and a clock synchronization signal. The phase synchronization stage is coupled to the retimed data signal and the clock synchronization signal. The phase synchronization stage is triggered by the retimed data signal and samples the clock synchronization signal to generate a phase control signal.

Abstract: To conserve power in a circuit where a high-speed signal HSIG controls combinational logic (10), while a low-speed signal LCLK drives a logic/memory circuit (12) that samples the output of the combinational logic, predictive logic state machine (14) generates a clock, P_LCLK, which has an active level preceding the active edge of LCLK by a period sufficient to allow the combinational logic to reach the desired state prior to the active edge of LCLK and, preferably, allows for possible jitter in LCLK. Responsive to P_LCLK, the signal suspend circuitry (16) either passes HSIG or gates off HSIG. Further reductions in power can be accomplished by predicting which portions of the logic/memory circuit (12) will be used, and clocking those portions.

Abstract: A digital phase detector that conducts pump up and pump down control signals to a charge pump, wherein each of the control signals has pulses that have a substantially 50/50 duty cycle characteristic when the two input signals, i.e., the input data signal and the feedback clock signal, are substantially in phase. This substantially 50/50 duty cycle output reduces, if not eliminates, inherent problems related to the turn-on delays of the charge pump while maintaining a locked condition. The phase detector may further include an intelligence to detect and handle other situations, such as missing data pulses.

Abstract: Semiconductor device testers are provided which measure skew between two or more output pins of a semiconductor device independent of a strobe timing input. More particularly, a skew signal is generated by a comparator circuit that changes state when the respective outputs transition state, for example, from matching to differing states. In a two output pin embodiment, for instance, when one of the output pin changes state before the other and both initially are in the same state, a flip flop is set at the time when the data on the output pins first differs, i.e. when the first output pin transitions to a new state. The flip flop is then reset when the second output pin subsequently transitions to the new state and again matches the first output pin. The resulting duration of the output of the flip flop thereby corresponds to the time of skew of the output pins regardless of the initial state of the pins.

Abstract: In a feedback system such as a PLL, the integrating function associated with a loop filter capacitor is instead implemented digitally and is easily implemented on the same integrated circuit die as the PLL. There is no need for either an external loop filter capacitor nor for a large loop filter capacitor to be integrated on the same integrated circuit die as the PLL. In a preferred embodiment, an analog phase detector is utilized whose phase error output signal is delta-sigma modulated to encode the magnitude of the phase error using a digital (i.e., discrete-time and discrete-value) signal. This digital phase error signal is “integrated” by a digital integration block including, for example, a digital accumulator, whose output is then converted to an analog signal, optionally combined with a loop feed-forward signal, and then conveyed as a control voltage to the voltage-controlled oscillator.

Abstract: A phase detector for a clock and data recovery circuit from random non-return-to zero (NRZ) data signal includes a plurality (e.g., preferably three) edge-triggered flip-flops. The incoming NRZ data are sampled by a pair of edge-triggered flip-flops using the transition of the clock generated by the clock recovery circuit. A third edge-triggered flip-flop processes the outputs from the edge-triggered flip-flop pair to indicate whether the generated clock leads or lags the received data.

Abstract: A double phase comparator sets both first and second signals to the “L” levels to delay a phase of a feedback clock signal when the feedback clock signals at rising and falling edges of an internal clock signal are at the “H” level and the “L” level respectively, or sets both first and third signals to the “L” levels to advance a phase of a feedback clock signal when the feedback clock signals at both edges are at the “L” level and the “H” level respectively, or sets the first signal to the “H” level to stop a phase control of the feedback clock signal when the levels of the feedback clock signal at both edges correspond.

Abstract: A lock detect indicator capable of dynamically determining whether a phase locked loop is in lock or out of lock is provided. The lock detect indicator uses pulses on the fast and slow signals generated by a phase-frequency detector of the phase locked loop to determine if the phase locked loop has been continuously trying to speed up or slow down itself for a predefined amount of time, in which case, the lock detect indicator indicates that the phase locked loop is out of lock. Further, a lock detect indicator capable of indicating whether a phase locked loop previously went out of lock is provided. Further, a method for detecting whether a phase locked loop is out of lock or in lock is provided.

Abstract: A high speed phase detector utilizes an integrated XOR/MUX circuit having a higher bandwidth and lower power than conventional designs. The XOR/MUX circuit combines the functionality of an XOR device in series with a multiplexer in a manner that increases the bandwidth of the function. In a practical implementation, the XOR/MUX circuit includes an XOR arrangement having a plurality of transistors implemented at a first transistor level and a plurality of transistors implemented at a second transistor level. The XOR/MUX circuit also includes transistors implemented at a third transistor level; these transistors are utilized by the multiplexer feature of the circuit.

Abstract: An apparatus comprising a first circuit and a second circuit. The first circuit may be configured to present (i) a pump up signal in response to a reference signal and a reset signal and (ii) a pump down signal in response to an input signal and the reset signal. The second circuit may be configured to (i) switch a pull up signal in response to the pump up signal, (ii) switch a pull down signal in response to the pump down signal, and (iii) present the reset signal in response to switching the pull up signal and the pull down signal.

Abstract: A phase detector system and method operate correctly, regardless of the point of time at which the operation of the delay locked loop is initialized with respect to the phases of reference and feedback clock signals. The system comprises a phase detector for a delay-locked loop for compensating for a difference in phase between a first clock signal and a second clock signal. The phase detector includes a first flip-flop receiving the first clock signal and generating a first output signal, the first flip-flop being reset by a first reset signal. A second flip-flop receives the reference clock signal and generates a second output signal, the second flip-flop being reset by a second reset signal, the first and second reset signals being sourced by separate logic paths.

Abstract: An improved DDLL containing a majority filter counter circuit is disclosed. The majority filter counter circuit is located between the phase detector and the shift register of the DDLL. The majority filter counter circuit receives shifting commands from the phase detector and filters the shift commands from reaching the shift register until a predetermined number (e.g., 16) have been received from the phase detector before transmitting a shift command (either shift right or shift left) to the shift register. Once the shift register receives the shift command, the shift register directs the delay line to shift by one tap in either a shift right or a shift left direction depending upon the phase relationship between CLKIn and CLKOut. By waiting for e.g., 16 shift commands, the majority filter counter circuit ensures that a premature shift command is not delivered to the shift register in the case of a noise event.

Abstract: An apparatus and method of compensating for differences in circuit routing path lengths is described. In one embodiment, a latch is inserted between reset signal generating logic and a pair of flip-flops. When a reset signal is generated, the reset signal is held inside the latch until both flip-flops are reset. A latch reset signal may be generated by the flip-flops to clear the latch. The circuit may be configured to ensure that both flip-flops are reset before the reset signal is disabled.

Abstract: A phase detector and corresponding method. The phase detector detects a transition of a first signal and generates an output signal having a first value if a transition of a second signal occurs before the transition of the first signal and having a second value if the transition of the second signal occurs after the transition of the first signal. The output signal is maintained at the generated value until another transition of the first signal is detected. A strobe signal may be used to strobe the output signal.

Abstract: A pulse detector detects if a clock pulse signal is in phase with a reference clock pulse signal in an efficient manner with very high accuracy. The pulse detector includes a first delay unit adapted to receive an input clock pulse signal and to delay the input clock pulse signal by a first pre-specified delay for output as output clock pulse signal, and a second delay unit adapted to delay the output clock pulse signal by a second pre-specified delay. A sampling unit is adapted to sample the input clock pulse signal and the output of the second delay unit at a sampling time defined by a reference clock pulse signal and to output the samples for phase delay indication.

Abstract: A method and apparatus are provided for capturing data read from a memory device that is aligned with respect to a clock strobe signal originating from the memory device, which has constraints with respect to a local clock signal supplied to the memory device. The apparatus includes a circuit for capturing the data read from the memory device relative to the clock strobe signal to produce captured read data, a circuit for latching the captured read data relative to a sample clock signal, and a circuit for measuring a phase difference between the sample clock signal and the clock strobe signal and adjusting a phase of the sample clock signal as a function of the phase difference.

Abstract: The invention relates to a phase detector. The phase detector includes data sampling cells to sample a stream of serial data and generate primary data samples and also includes edge data sampling cells to sample the stream of serial data and generate edge data samples. The phase detector further includes phase detecting cells to generate phase control signals. Each phase detecting cell includes a first circuit to receive data and sampled edge data and to generate a first signal and a second signal. The first signal from a phase detecting cell is a delayed sampled edge data. The second signal from that phase detecting cell will be a delayed sampled edge data before data is sampled by the data sampling cell. Once data is sampled by the data sampling cell, the second signal from that phase detecting cell will be a secondary data sample. Each phase detecting cell also includes a comparator circuit to receive the first signal and second signal and to generate a phase control signal therefrom.

Abstract: A phase measurement circuit includes first and second complementary clock strobe inputs, a local clock input and a sample clock output. A programmable delay line is coupled between the local clock input and the sample clock output and has a plurality of propagation delay settings. First and second toggle circuits are clocked by the first and second clock strobe inputs, respectively, and each has a toggle output that changes state when clocked by the respective first or second clock strobe input. A capture latch circuit has first and second data inputs coupled to the toggle outputs of the first and second toggle circuits, respectively, has first and second capture outputs, and is clocked by the sample clock output. A synchronizer circuit has first and second data inputs coupled to the first and second capture outputs, respectively, has first and second synchronized capture outputs, and is clocked by the local clock input.

Abstract: A phase comparator which eliminates jitter in a clock signal extracted in a phase locked loop. The phase comparator includes: a flip-flop circuit which inputs input data and the clock signal and stores the input data in response to the clock signal; a delay circuit which inputs the input data and delays the input data by a predetermined angle of 0° through 180°; a first logic gate which inputs the input data and an output signal of the flip-flop circuit and which outputs an output signal by taking an exclusive OR or exclusive NOR thereof; and a second logic gate which inputs the data and the output signal of the delay circuit and which outputs an output signal by taking an exclusive OR or exclusive NOR thereof.

Abstract: An improvement to a phase and frequency detector (PFD) employs an additional reset control that acts to effectively reset the registers that generate the phase indicator signals if an undesirable preconditioned state has been entered. The additional reset control signal is generated by a register that is enabled upon detection of the preconditioned state. The new reset control signal is activated upon detection of a synchronizing signal, that is based on an input source signal, while the enable control is active. The improved detector can allows a phase locked loop (PLL) system locking to the nearest input reference clock edge and it can provide immunity to missing input clock edges.

Abstract: A digital signal phase detector comprising a first circuit arranged to provide a phase difference signal representative of both the clock period of a clock signal and the difference in phase between the clock and a data signal, and a second circuit arranged to provide a reference signal representative of the clock period of the clock signal. At least one of the first and second circuits is coupled to a set point control signal and the corresponding output signal is representative of that set point control signal. A comparison of the phase difference signal with the reference signal provides an indication of the difference between the desired set point of the circuit and the phase difference between the clock and the data signal. A corresponding method of digital signal phase detection is also provided.

Abstract: A phase frequency detector (PFD) circuit (516) compares two clock signals and generates a number of outputs to indicate a phase difference between these two clock signals (513, 519). The phase frequency detector has more than three states. The PFD circuit may be used in phase locked loop (PLL) or delay locked loop (DLL) circuit in order to maintain or lock a phase relationship between the two clock signals. The PFD circuitry will allow for a fast lock acquisition time, even when there is a relatively wide frequency range between the two clock signals.

Abstract: Phase-reset circuits provide first and second frequency-divided input signals to a phase/frequency detector (PFD) used in a phase-locked loop (PLL). The phase-reset circuits receive first and second input signals, with the first input signal usually serving as a reference signal against which the PLL adjusts the second input signal. The PFD generates control signals based on the phase difference between the frequency-divided input signals. Normally, the phase-reset circuits frequency divide the first and second input signals using divisors N and M, respectively. If other circuitry detects that the PFD has missed a clock cycle in the first or second clock-divided input signals, the corresponding phase-reset circuit alters its divider so that the next clock edge on the corresponding input signal clocks through to the PFD. This causes the PFD to quickly set its affected control signal to what it would have been had the clock cycle not been missed.

Abstract: Apparatus for generating an oscillating signal in a desired phase relationship with an input signal, including a mixer arranged to receive a pair of reference signals oscillating at a common frequency and having a phase offset between them, and to mix the reference signals in variable proportions according to the value of input weighting signals to generate an output signal. A comparator is to compare the phase of the output signal with that of the input signal to determine whether the signals are in the desired phase relationship and, if not, to output one or more control signals indicative of the required adjustment in the phase of the output signal to achieve the desired phase relationship. An adjustable ring oscillator including a plurality of stages is connected in a ring and arranged to propagate oscillations around the ring.

Abstract: A phase frequency detector (PFD) circuit (516) compares two clock signals and generates a number of outputs to indicate a phase difference between these two clock signals (513, 519). The phase frequency detector has more than three states. The PFD circuit may be used in phase locked loop (PLL) or delay locked loop (DLL) circuit in order to maintain or lock a phase relationship between the two clock signals. The PFD circuitry will allow for a fast lock acquisition time, even when there is a relatively wide frequency range between the two clock signals.

Abstract: Phase-reset circuits provide first and second frequency-divided input signals to a phase/frequency detector (PFD) used in a phase-locked loop (PLL). The phase-reset circuits receive first and second input signals, with the first input signal usually serving as a reference signal against which the PLL adjusts the second input signal. The PFD generates control signals based on the phase difference between the frequency-divided input signals. Normally, the phase-reset circuits frequency divide the first and second input signals using divisors N and M, respectively. If other circuitry detects that the PFD has missed a clock cycle in the first or second clock-divided input signals, the corresponding phase-reset circuit alters its divider so that the next clock edge on the corresponding input signal clocks through to the PFD. This causes the PFD to quickly set its affected control signal to what it would have been had the clock cycle not been missed.

Abstract: A digital fractional phase detector is provided to realize a frequency synthesizer architecture that naturally combines transmitter modulation capability with a wideband all-digital PLL modulation scheme to maximize a digitally-intensive implementation by operating in a synchronous phase domain. Synchronous logic is provided across a digitally controlled VCO and is synchronous to the VCO output clock by implementing a timing adjustment in association with a reference calculation to allow a frequency control word to contain both channel information and transmit modulation information. The digital fractional phase detector is capable of accommodating a quantization scheme to measure fractional delay differences between the significant edge of the VCO output clock and a reference clock by using a time-to-digital converter to express the time difference as a digital word for use by the frequency synthesizer.

Abstract: In a first aspect, a lock indicator circuit is disclosed. The lock indicator comprises a first circuit for providing a first beat signal; and a second circuit for providing a second beat signal. A reference clock signal and a recovered clock signal are provided in a reversed manner to the first and second circuits. In a second aspect, a method for providing a lock indication of a circuit is disclosed. The method comprises the steps of providing a first and second beat signals; and utilizing the first and second beat signals to determine if a lock condition has occurred. A system and method in accordance with the present invention indicates a lock to the desired reference clock and provides an error or out of lock condition if the recovered frequency is at a harmonic or subharmonic of the reference frequency. This ability to avoid a false lock indication requires very little additional circuitry.

Abstract: A digital phase shift amplification and detection system and method. A signal is applied to a digital phase shift amplifier including a flip flop operated in the metastable region which amplifies any timing changes in the signal. The amplified signal is fed into a detection circuit configured to detect timing delays in the amplified signal. In one embodiment, the present invention relates to a digital phase shift amplification and detection system and method. A signal is applied to a digital phase shift amplifier including a flip flop operated in the metastable region which amplifies any timing changes in the signal. The amplified signal is fed into a detection circuit configured to detect the amplified timing differences in the amplified signal as a result of a relatively smaller timing change in an input signal. The detection circuit is coupled to clock signals that are out of phase with the clock signal that triggers the metastable flip flop in the phase shift amplifier.

Abstract: In a first aspect, a lock indicator circuit is disclosed. The lock indicator comprises a first circuit for providing a first beat signal; and a second circuit for providing a second beat signal. A reference clock signal and a recovered clock signal are provided in a reversed manner to the first and second circuits. In a second aspect, a method for providing a lock indication of a circuit is disclosed. The method comprises the steps of providing a first and second beat signals; and utilizing the first and second beat signals to determine if a lock condition has occurred. A system and method in accordance with the present invention indicates a lock to the desired reference clock and provides an error or out of lock condition if the recovered frequency is at a harmonic or subharmonic of the reference frequency. This ability to avoid a false lock indication requires very little additional circuitry.