An apparatus includes a digitally controlled oscillator (DCO), which includes an inductor coupled in series with a first capacitor. The DCO further includes a second capacitor coupled in parallel with the series-coupled inductor and first capacitor, a first inverter coupled in parallel with the second capacitor, and a second inverter coupled back-to-back to the first inverter. The DCO further includes a digital-to-analog-converter (DAC) to vary a capacitance of the first capacitor.

The disclosure discloses a coarse adjustment cell array applied to a digitally controlled oscillator and a related apparatus. The coarse adjustment cell array applied to the digitally controlled oscillator includes X coarse adjustment cells, and each coarse adjustment cell in the coarse adjustment cell array includes a logic cell and W fine adjustment cells; and input to a logic cell of a coarse adjustment cell i in the coarse adjustment cell array includes Y coarse adjustment control bits and W fine adjustment control bits, output from the logic cell of the coarse adjustment cell i is used to control whether W fine adjustment cells in the coarse adjustment cell i work, Y is an integer greater than 1, and X and W are integers greater than 1.

A method includes generating first frequency metrics for a first received network clock signal using a local reference clock signal. The method includes, in response to the first received network clock signal being available and satisfying a quality metric, generating a network delay estimate using a first error estimate based on the first received network clock signal, and updating stored frequency metrics for the first received network clock signal with the first frequency metrics. The method includes generating an output clock signal based on received packets and the network delay estimate. The first frequency metrics for the first received network clock signal may include a current average frequency count, a prior average frequency count, a standard deviation of prior average frequency counts and a multiplicative constant corresponding to a number of samples used to determine the current average frequency count, prior average frequency count, and standard deviation.

An apparatus includes a first function module providing a master signal, a second function module providing a comparison signal, and safety logic. The safety logic includes a toggle signal generator having a comparator providing a comparison result in response to the master signal and the comparison signal, a feedback path generating a first toggle signal in response to the comparison result and providing a feedback signal to the comparator, and a first multiple input gate generating a second toggle signal in response to the comparison result. The safety logic also includes a toggle signal monitor providing a final fault search signal in response to the first toggle signal and the second toggle signal.

A phase-locked loop (PLL) including a multiplexer with multiple inputs, each input coupled to receive a different reference clock. A time-to-digital converter (TDC) generates a TDC output value based on a phase difference between a reference clock from the multiplexer and a feedback clock. An averager circuit coupled to an output of the TDC. An adder circuit is coupled to outputs of the TDC and the averager circuit. A loop filter is coupled to an output of the adder circuit.

There is provided a signal generator and associated method for generating a source signal. The signal generator includes a frequency generator for providing an oscillating signal, a phase comparator, a first phase modulator, a second phase modulator and a phase shifter. The phase comparator is adapted to compare a phase signal with a feedback signal and to generate an error signal to control the phase of the oscillating signal. The first and second phase modulators are adapted to provide a first phase control word and a second phase control word respectively. The phase shifter is adapted to modulate the oscillating signal based on the second phase control word to generate the source signal. The source signal comprises the feedback signal.

A method can be used for managing the operation of a phase-locked loop. The loop includes an oscillator voltage controlled by a control signal and a phase comparator receiving a reference signal and a feedback signal which arises from the output signal of the oscillator. The method includes a detection of a possible absence of transitions on the feedback signal for a first duration and, in response to such an absence, a forcing of the lowering of the voltage of the control signal at least until a reappearance of transitions on the feedback signal.

A system and method to dynamically control a reset signal for an IQ divider are provided. The system includes an IQ divider configured to output a IQ divider output clock; an input configured to receive a reference clock; a failure sensing circuit configured to sense a failure in the IQ divider output clock, the failure sensing circuit including an automatic frequency calibration (AFC) logic; and a control circuit configured to control a reset signal provided to the IQ divider, based on an output of the failure sensing circuit corresponding the failure sensed by the failure sensing circuit.

A phase-locked loop (PLL) including a multiplexer with multiple inputs, each input coupled to receive a different reference clock. A time-to-digital converter (TDC) generates a TDC output value based on a phase difference between a reference clock from the multiplexer and a feedback clock. An averager circuit coupled to an output of the TDC. An adder circuit is coupled to outputs of the TDC and the averager circuit. A loop filter is coupled to an output of the adder circuit.

A method for operating a clock product includes generating a quality determination for a reference clock signal based on frequency metrics for a plurality of independent clock signals. The frequency metrics are generated using the reference clock signal. The method includes generating an output clock signal by locking to an active clock signal selected from the plurality of independent clock signals in response to the quality determination satisfying a predetermined quality metric. For each input clock signal of the plurality of independent clock signals, the frequency metrics include a current average frequency count, a prior average frequency count, a standard deviation of prior average frequency counts, and a multiplicative constant corresponding to a number of samples used to determine the current average frequency count, prior average frequency count, and standard deviation.