A locked loop circuit includes a controlled oscillator generate an output signal having a frequency set by an analog control signal. The analog control signal is generated by a first digital-to-analog converter (DAC) in response to a digital control signal and a bias compensation current signal. The bias compensation current signal is generated by a second DAC in response to a compensation control signal and a bias reference current. A compensation circuit adjusts the compensation control signal during compensation mode in response to a comparison of a frequency of the output signal to a frequency of a reference signal so as to drive the frequency of the output signal toward matching a desired frequency. The bias compensation current signal associated with the frequency match condition during compensation mode is then used during locked loop mode.

A locked loop circuit includes a controlled oscillator generate an output signal having a frequency set by an analog control signal. The analog control signal is generated by a first digital-to-analog converter (DAC) in response to a digital control signal and a bias compensation current signal. The bias compensation current signal is generated by a second DAC in response to a compensation control signal and a bias reference current. A compensation circuit adjusts the compensation control signal during compensation mode in response to a comparison of a frequency of the output signal to a frequency of a reference signal so as to drive the frequency of the output signal toward matching a desired frequency. The bias compensation current signal associated with the frequency match condition during compensation mode is then used during locked loop mode.

A source-synchronous clocking signal is sampled by an edge sampler triggered by a phase-adjusted version of the clocking signal. The output of the edge sampler is used as a phase-error indicator for a filtered feedback loop that aligns the phase-adjusted clocking signal to minimize, on average, the difference between the received source-synchronous clocking signal and the phase-adjusted version of the clocking signal minus the setup time of the sampler. This forms a delay-locked loop configuration. The phase adjustment information used to produce the aligned phase-adjusted clocking signal is then to produce a receiver clocking signal that is used to sample the source-synchronous data signal.

A source-synchronous clocking signal is sampled by an edge sampler triggered by a phase-adjusted version of the clocking signal. The output of the edge sampler is used as a phase-error indicator for a filtered feedback loop that aligns the phase-adjusted clocking signal to minimize, on average, the difference between the received source-synchronous clocking signal and the phase-adjusted version of the clocking signal minus the setup time of the sampler. This forms a delay-locked loop configuration. The phase adjustment information used to produce the aligned phase-adjusted clocking signal is then to produce a receiver clocking signal that is used to sample the source-synchronous data signal.

Embodiments of an integrated circuit (IC) comprising circuitry to determine settings for an injection-locked oscillator (ILO) are described. In some embodiments, an injection signal is generated based on a first clock edge of a reference clock signal, and is injected into an ILO. Next, one or more output signals of the ILO are sampled based on a second clock edge of the reference clock signal, and settings for the ILO are determined based on the samples. In some embodiments, a sequence of two or more time-to-digital (TDC) codes is generated based on a reference clock signal and a free-running ILO. In some embodiments, the TDC circuitry that is already present in a delay-locked loop is reused for determining the sequence of two or more TDC codes. The ILO settings can then be determined based on the sequence of two or more TDC codes.

A circuit device includes a driving circuit that generates a clock signal by oscillating a vibrator, a master clock signal generation circuit that generates a master clock signal, and a master clock signal failure detection circuit that detects a failure of the master clock signal. The master clock signal failure detection circuit detects the failure of the master clock signal on the basis of an error detection clock signal, which is the clock signal from the driving circuit, and the master clock signal.

A hybrid numeric-analog clock synchronizer, for establishing a clock or carrier locked to a timing reference. The clock may include a framing component. The reference may have a low update rate. The synchronizer achieves high jitter rejection, low phase noise and wide frequency range. It can be integrated on chip. It may comprise a numeric time-locked loop (TLL) with an analog phase-locked loop (PLL). Moreover a high-performance number-controlled oscillator (NCO), for creating an event clock from a master clock according to a period control signal. It processes edge times rather than period values, allowing direct control of the spectrum and peak amplitude of the justification jitter. Moreover a combined clock-and-frame asynchrony detector, for measuring the phase or time offset between composite signals. It responds e.g. to event clocks and frame syncs, enabling frame locking with loop bandwidths greater than the frame rate.

A hybrid numeric-analog clock synchronizer, for establishing a clock or carrier locked to a timing reference. The clock may include a framing component. The reference may have a low update rate. The synchronizer achieves high jitter rejection, low phase noise and wide frequency range. It can be integrated on chip. It may comprise a numeric time-locked loop (TLL) with an analog phase-locked loop (PLL). Moreover a high-performance number-controlled oscillator (NCO), for creating an event clock from a master clock according to a period control signal. It processes edge times rather than period values, allowing direct control of the spectrum and peak amplitude of the justification jitter. Moreover a combined clock-and-frame asynchrony detector, for measuring the phase or time offset between composite signals. It responds e.g. to event clocks and frame syncs, enabling frame locking with loop bandwidths greater than the frame rate.

A reference frequency calibration module is provided. The reference frequency calibration module includes an oscillator, a frequency divider, a phase-locked loop (PLL) and a frequency-offset calibration unit. The frequency divider couples to the oscillator. The phase-locked loop couples to the frequency divider. The frequency-offset calibration unit couples to the frequency divider and the phase-locked loop. The oscillator is configured for operatively generating an oscillating signal having an oscillating frequency. The frequency divider divides the oscillating signal having the oscillating frequency by a first division parameter to generate a first clock signal having a first reference frequency. The phase-locked loop generates a second clock signal having a second reference frequency according to the first clock signal. The frequency-offset calibration unit is configured for operatively generating the first division parameter according to the second clock signal.

A reference frequency calibration module is provided. The reference frequency calibration module includes an oscillator, a frequency divider, a phase-locked loop (PLL) and a frequency-offset calibration unit. The frequency divider couples to the oscillator. The phase-locked loop couples to the frequency divider. The frequency-offset calibration unit couples to the frequency divider and the phase-locked loop. The oscillator is configured for operatively generating an oscillating signal having an oscillating frequency. The frequency divider divides the oscillating signal having the oscillating frequency by a first division parameter to generate a first clock signal having a first reference frequency. The phase-locked loop generates a second clock signal having a second reference frequency according to the first clock signal. The frequency-offset calibration unit is configured for operatively generating the first division parameter according to the second clock signal.