A frequency counter circuit includes a first counter path to receive a digitally-controlled oscillator (DCO) clock signal and is configured to generate a first count corresponding to a first frequency of a first reduced clock signal corresponding to the DCO clock signal. A second counting path receives the DCO clock signal and generates a second count corresponding to a second frequency of a second reduced clock signal corresponding to the DCO clock signal. The first reduced clock signal is an integer multiple frequency of the second reduced clock signal. Detection circuitry detects a timing violation associated with the DCO clock signal based on a comparison between at least a portion of the first count and at least a portion of the second count.

A system includes a ring oscillator including an odd number of inverters arranged in a ring. The system also includes a time to digital converter including an odd number of flops, where each of the flops is coupled to an output of a different inverter. The system includes a level shifter coupled to the inverters and to the flops. The system also includes a Gray counter coupled to at least one of the flops. The system includes a decoder coupled to the time to digital converter. The system also includes a phase frequency detector coupled to the decoder.

The present application discloses a circuit for generating spread-spectrum synchronous clock signal. The circuit includes a frequency detector comprising a fraction controller configured to compare an input signal of a first frequency with a feedback signal of a second frequency in a loop of feedback to generate a first control signal and a second control signal alternately for determining a control word to track the first frequency and a phase-shift controller configured to register n levels for the first control signal and the second control signal to introduce n phase delays for changing a fraction part of the control word randomly to provide a broadened boundary. The circuit also includes a digitally controlled oscillator configured to generate a synthesized periodic signal based on a base time unit, the first frequency, and the control word, with the second frequency being locked within the broadened boundary of the first frequency.

A phase correcting device includes a local oscillator that includes an all digital phase-locked loop configured to output a local oscillation signal, a first phase detector configured to detect a phase of the local oscillation signal to output the phase of the local oscillation signal, a reference phase device configured to generate a quasi-reference phase corresponding to a reference phase of the local oscillation signal to output the quasi-reference phase, based on a reference clock, a second phase detector configured to detect a fluctuation amount of a phase of the local oscillator, based on the phase detected by the first phase detector and the quasi-reference phase, and a correction circuit configured to correct the phase of the inputted signal by using a detection result of the second phase detector.

To improve power converter ON-time generation, an example apparatus includes: a phase frequency detector to determine a phase difference between a first signal and a second signal; a first pulse generator to generate a first time signal at a second time, in which the first signal is associated with a first time delay based on the phase difference; and a second pulse generator coupled to the first pulse generator. The second pulse generator is configured to: generate a second time signal at a third time, in which the third time is after the second time; and obtain a digital word based on the phase difference at a first time, in which the first time is before the second time and the third time, and the second time signal is associated with a second time delay based on the phase difference.

The present disclosure discloses a clock and data recovery circuit. The clock and data recovery circuit may include a clock recovery unit configured to output a recovery clock signal by operating a first time-to-digital conversion circuit or a second time-to-digital conversion circuit depending on a phase difference between a clock of an input signal and the recovery clock signal, and a data recovery unit configured to sample data from the input signal and output recovery data.

A method of calibrating an All-Digital Phase Locked Loop (ADPLL) includes obtaining a model of the ADPLL and applying an input signal to both the ADPLL and to the model. The ADPLL generates an actual output of the ADPLL, while the model generates a model output. An error between the actual output of the ADPLL and the model output is then sensed. The method also includes generating a calibration value based on the error between the actual output of the ADPLL and the model output, and adjusting a feedforward gain of the ADPLL based on the calibration value.

A time to digital converter has a counter, a first phase difference detector, a first capacitor, a second capacitor having capacitance N times a capacitance of the first capacitor, a comparator to compare a charge voltage of the first capacitor with a charge voltage of the second capacitor, a first charge controller, a first phase difference arithmetic unit, a second phase difference detector, a second charge controller, a second phase difference arithmetic unit to operate the phase difference between the first signal and the second signal, and a third phase difference arithmetic unit to detect a fractional phase difference between the first signal and the second signal. The first phase difference arithmetic unit operates the phase difference between the first signal and the second signal, based on a reference phase, when the counter suspends a measurement operation.

A phase locked loop is disclosed comprising: a phase detector, a loop filter, a frequency controller oscillator and a lock detector. The phase detector is operable in a bang-bang mode to provide a binary phase error signal indicating whether there is a positive or negative phase difference between a reference signal and a feedback signal. The loop filter is configured to provide a control signal derived from the binary phase error signal. The frequency controlled oscillator is configured to receive the control signal and provide an output signal with a frequency that varies according to the control signal. The lock/unlock detector is configured to determine a lock/unlock state of the phase locked loop, the lock/unlock state derived from a duty cycle and/or spectral content of the binary phase error signal.

A method for clock frequency monitoring for a Phase-Locked Loop (PLL) based design includes determining a present operating point of an oscillator of the PLL based design, wherein the oscillator generates a present frequency in response to the present operating point. The present operating point of the oscillator is compared to a comparison range defined by a plurality of reference operating points, wherein the oscillator generates a nominal reference frequency in response to a nominal one of the plurality of reference operating points and the comparison range is further defined by a manufacturing process range, an operating voltage range and an operating temperature range. An action is performed in response to the present operating point being outside of the comparison range.