A division factor generator of a feedback divider block in a fractional-N phase locked loop (PLL). The division factor generator is enabled to operate with larger values of division factors without increased complexity of an internal modulator core implemented, for example, as a delta-sigma modulator (DSM) having a signal transfer function (STF), wherein the STF always generates only an integer value as an output in response to an integer value received as input.

A clock-and-data recovery circuit for serial receiver includes a jitter meter and an adaptive loop gain adjustment circuitry. The clock-recovery circuitry phase aligns a clock signal to the incoming data. A jitter meter provides a measure of jitter, while adaptation circuitry uses the measure to adjust the clock-recovery circuitry in a manner that reduces clock jitter. The jitter measure can be a ratio of errors associated with different inter-symbol slew rates.

Enhancing the accuracy in compensating errors caused by a reference signal with unequal successive periods in a fractional-N phase locked loop (PLL). A compensation block generates a compensation factor, and is implemented based on a correction block and a filter. The correction block generates a correction signal containing a first frequency correction factor and a second frequency correction factor for a first period and a second period constituting each pair of successive periods, with the correction signal also containing a noise component at direct current (DC). The filter operates to remove the noise component at DC from the correction signal to generate a compensation factor containing the first frequency correction factor and the second frequency correction factor. The compensation factor thus generated may be provided as an input to a division factor generator of a frequency divider block of the PLL, potentially resulting in zero error frequency synthesis.

Disclosed are a control signal pulse width extraction-based phase-locked acceleration circuit and a phase-locked loop system, the phase-lock acceleration circuit includes a pulse width extraction control circuit and a current injection switch module; the control output terminal of the pulse width extraction control circuit is connected to the current injection control terminal of the current injection switch module, and the stepping current control terminal of the current injection switch module and the driving input terminal of the pulse width extraction control circuit are both connected to the preset control signal output end of a phase frequency detector for use in controlling, according to pulse width changes of signals outputted by the preset control signal output end, the current injection switch module to inject charges until the phases of a reference clock signal and feedback clock signal inputted by the phase frequency detector are synchronized.

Some embodiments include apparatuses having a first path in a phase locked loop, the first path including a phase frequency detector to receive a first signal having a first frequency and a first node to provide a voltage; an oscillator coupled to a second node and the first node to provide a second signal having a second frequency at the second node; a second path including a frequency divider coupled to the second node and the phase frequency detector; and a circuit to generate digital information having a value based on a value of the voltage at the second node.

A quantizer generates a thermometer coded signal from an analog voltage signal. Data weighted averaging (DWA) of the thermometer coded signal is accomplished by controlling the operation of a crossbar switch controlled by a switch control signal to generate an output DWA signal. The output DWA signal is latched to generate a latched output DWA signal which is processed along with bits of the thermometer coded input signal in feedback loop to generate the switch control signal. The latching of the output DWA signal is performed in an input register of a digital-to-analog converter which operates to convert the latched output DWA signal to a feedback analog voltage from which the analog voltage signal is generated. The switch control signal specifies a bit location for a beginning logic transition of the output DWA signal cycle based on detection of an ending logic transition of the latched DWA signal.

A system and method for a frequency detector circuit includes: a transition detector configured to receive a data input and provide a first edge output based on transitions in the data input; a first circuit configured to generate a second edge output; a second circuit configured to generate a third edge output; and a combinational logic configured to output an UP output when at least two of the first edge output, the second edge output, and the third edge output are high and configured to output a DOWN output when the first edge output, the second edge output, and the third edge output are all low.

A lock detection circuit is configured to include an integrating circuit that integrates a phase difference between a frequency-divided signal of a VCO and a reference signal during a constant period within a transient response period for an output signal from the VCO, and integrates a phase difference between the frequency-divided signal and the reference signal during a constant period within a convergence period for the output signal from the VCO; and a degree-of-convergence calculating circuit that calculates a degree at which the output signal from the VCO has converged, from a result of the integration of the phase difference obtained by the integrating circuit during the constant period within the transient response period and a result of the integration of the phase difference obtained by the integrating circuit during the constant period within the convergence period.

Some embodiments include apparatuses having a first path in a phase locked loop, the first path including a phase frequency detector to receive a first signal having a first frequency and a first node to provide a voltage; an oscillator coupled to a second node and the first node to provide a second signal having a second frequency at the second node; a second path including a frequency divider coupled to the second node and the phase frequency detector; and a circuit to generate digital information having a value based on a value of the voltage at the second node.

Embodiments may relate to techniques or circuitry for the control of a clock signal by a phase-locked loop (PLL) circuit. The technique may include the identification of a first parameter related to a gain of a digitally controlled oscillator (DCO) and a second parameter related to a resolution of a time-to-digital converter (TDC). The technique may then include the identification of a third parameter related to filter coefficients of a loop filter of the PLL circuit based on the first and second parameter. The circuit may then output a clock signal based on the first, second, and third parameters. Other embodiments may be described or claimed.