A digitally controlled oscillator (DCO) that generates an output frequency clock signal without drift and can be rapidly locked to an input or reference clock is described. A variable-modulus-fixed-increment form of DCO is configured to divide the frequency of a nominally fixed frequency oscillator. A constant is derived from the ratio of a fixed increment to the desired output frequency; this constant is multiplied by the frequency of the oscillator and the modulus adjusted to keep the ratio of the input clock and the output clock constant. The frequency of the oscillator is conveniently measured by counting the number of cycles between input cycles of a reference frequency. The oscillator must be greater in frequency than the expected output and is most accurate in cases where the reference frequency is low compared to the expected output frequency.

A self-calibration time-to-digital converter (TDC) integrated circuit for single-photon avalanche diode (SPAD) based depth sensing is disclosed. The circuit includes a SPAD matrix with a plurality of SPAD pixels arranged in m rows and n columns, the SPAD pixels in each column of SPAD pixels are connected by a column bus; a global DLL unit with n buffers and n clock signals; and an image signal processing unit for receiving image signals from the column TDC array. The circuit can also include a row control unit configured to enable one SPAD pixel in each row for a transmitting signal; a circular n-way multiplexer for circularly multiplexing n clock signals in the global DLL unit; a column TDC array with n TDCs, each TDC further comprises a counter and a latch, the latch of each TDC is connected to the circular n-way multiplexer for circular multiplexing.

A phase locked loop device may include: a frequency modulating circuit configured to output a reference signal obtained by multiplying a frequency of an input signal by a predetermined ratio based on the input signal; a sigma-delta modulator configured to output division ratio information on one of a plurality of division rates at a number of times proportional to a frequency of the reference signal; and a phase locked loop (PLL) circuit configured to determine whether to activate based on a command signal, and, when activated, perform a phase-locking operation based on a fractional division based on the reference signal and the division ratio information.

In described examples, an electronic circuit for determining a phase difference between a first clock signal and a second clock signal includes a timer circuit, circuitry for generating a selectively delayed transition of the second clock signal, and phase determination circuitry. The timer circuit produces an elapsed time between a transition of the first clock signal and the selectively delayed transition of the second clock signal. The circuitry for generating the selectively delayed transition of the second clock signal generates the selectively delayed transition in response to a random selection of a respective output from a plurality of second clock signal delay stages. The phase determination circuitry provides the phase difference in response to the elapsed time and the random selection of a respective output from a plurality of second clock signal delay stages.

An eye width monitor (EWM) for a clock and data recovery (CDR) circuit includes a delay circuit, a first multiplexer (MUX) and a calibration circuit. The delay circuit includes an input terminal and an output terminal. The first MUX, coupled to the delay circuit, includes a first input terminal, a second input terminal and an output terminal. The first input terminal of the first MUX is coupled to a clock input terminal of the EWM. The second input terminal of the first MUX is coupled to the output terminal of the delay circuit. The output terminal of the first MUX is coupled to the input terminal of the delay circuit. The calibration circuit, coupled to the delay circuit, is configured to receive an oscillation clock from the delay circuit and receive a reference clock, and calibrate the oscillation clock with the reference clock.

A method of using an analog-to-digital converter system includes receiving a sampled voltage corresponding to one of an input voltage and a known voltage, causing preamplifiers to generate output signals based on the sampled voltage, generating first and second signals based on the output signals, causing a delay-resolving delay-to-digital backend to generate a single-bit digital signal representing an order of receipt of the first and second signals, and adjusting one or more of the preamplifiers based on the digital signal. The disclosure also relates to a system which includes a voltage-to-delay frontend and a delay-resolving backend, and to a method which includes causing a delay comparator to generate a single-bit digital signal representing an order of receipt of input signals, causing the comparator to transmit a residue delay signal to a succeeding comparator, and transmitting a signal to adjust one or more of the preamplifiers based on the digital signal.

Injection locked resonator-based oscillators in accordance with various embodiments of the invention are described. An embodiment includes an injection locked resonator-based oscillator, that includes: an amplifier, a feedback circuit, a delayed locked loop (DLL), an off-chip high-frequency resonator that generates a resonance frequency, a switch connected to a power source V.sub.dd, and a voltage-controlled oscillator (VCO), where an input to the amplifier is connected to both the high-frequency resonator and the DLL to lock a signal, where an output from the amplifier is connected to the feedback circuit that is provided back to the high-frequency resonator.

An integrated circuit may include a receiver configured to receive a first data signal based on an m.sup.th (where m is an integer of 1 or more) transmitter preset setting among a plurality of transmitter preset settings through an external link, and equalize and sample the first data signal; a receiver setting table including a plurality of combinations including values of a plurality of parameters related to the receiver; and a receiver control circuit configured to sequentially select the plurality of combinations with reference to the receiver setting table and set the plurality of parameters with the selected combinations.

A device includes a master delay-lock loop (DLL) having a phase frequency detector connected in series with a charge pump that is to generate a control voltage. A slave DLL is coupled to the master DLL and has a delay line including a buffer to receive a slave clock and a series of delay cells coupled between the buffer and an output terminal that is to output a delay clock, the series of delay cells variably controlled by the control voltage. The master DLL and the slave DLL are powered by a power supply that experiences undershoot or overshoot in response to a load transient. A dummy load is coupled between the delay line of the slave DLL and an output of the power supply, the dummy load including an exclusive OR gate that receives, as inputs, a first output of the buffer and the delay clock.

A device includes a phase detector circuit, a charge pump circuit, a sample and hold circuit, a comparator, and a controller. The phase detector circuit detects a clock skew between a reference signal and an input signal. The charge pump circuit translates the clock skew into a voltage. A sample and hold circuit samples the voltage, at a first time, and maintain the sampled voltage until a second time. The comparator (i) detects a loop gain associated with the input signal based on the sampled voltage and the voltage at the second time and (ii) outputs a loop gain signal for adjustment of the input signal. The controller is coupled to the phase detector, the comparator, and the sample and hold circuit. The controller generates a plurality of control signals for automatically controlling operation of the phase detector, the comparator, and the sample and hold circuit.