A system delays input clock signals using time-to-digital converters (TDCs) to convert edges or the clock signals to digital values and storing the digital values in a memory. The digital values are retrieved from the memory based on a desired delay. A time counter used by the TDCs to determine the edges is also used determine the delay. The accuracy and range of the delay depends on the time counter and size of the memory.

Time-to-digital converter (TDC) using multiple Vernier in a cascaded architecture reduces the timing jitter by decreasing the number of the ring oscillator cycles during the measurement processes. Time-to-digital converter (TDC) measurements using a third oscillator for the second Vernier process has significant advantages compared to changing the period of the second oscillator during the measurement cycle. The Vernier architecture described herein may operate with faster oscillators, reducing the number of intervals before converging and leading to a lower time conversion and a better timing jitter Adding multiple cascaded Vernier interpolation may further improve the TDC measurement resolution while having only a small increment of time required to resolve the time interval calculations.

A time-to-digital converter (TDC) circuit includes phase error calculation circuitry to: determine phase error values based on a time difference between a input reference clock and a feedback clock of a digital phase-locked loop (DPLL) circuit, the input reference clock and the feedback clock being unsynchronized; and provide the phase error values to a digital loop filter (DLF) of the DPLL circuit. The TDC circuit further includes clock generation circuitry to: generate a filter clock that asserts a clock pulse in response to detecting each last-received pulse of the input reference clock and the feedback clock; and provide the filter clock to the DLF concurrently with providing the phase error values to the DLF that are synchronized to the filter clock.

An apparatus includes a first digital-to-time converter (DTC) and a second DTC. The first DTC includes a sequence of delay stages. Each of the delay stages adds a delay to an input signal based on a control signal. Each delay stage includes a comparator and a capacitor coupled to an input of the comparator and to ground. The second DTC is coupled in parallel to the first DTC. The second DTC adds a delay to the input signal based on a complement of the control signal.

A time-to-digital converter (TDC) circuitry is disclosed for converting a phase difference between an input reference signal (109) and an input clock signal (110) to a digitally represented output signal (139). The TDC circuitry comprises a plurality of constituent TDC:s (101, 102, 103), a reference signal provider (120), and a digital signal combiner (130). Each constituent TDC is configured to convert a phase difference between a constituent reference signal (181, 182, 183) and a constituent clock signal (110) to a digitally represented constituent output signal (131, 132, 133). The reference signal provider (120) is configured to provide the respective constituent reference signals (181, 182, 183) to each of the constituent TDC:s (101, 102, 103). In at least a parallel operation mode of the TDC circuitry, each respective constituent reference signal comprises a respectively delayed version of the input reference signal (109) with different respective delays for at least two of the respective constituent reference signals. The digital signal combiner (130) is configured to provide the digitally represented output signal (139) based on the digitally represented constituent output signals (131, 132, 133) of the constituent TDC:s. A corresponding method and devices comprising the TDC circuitry are also disclosed.

A calibration unit and method therein for calibrating a TDC comprised in a digital PLL are disclosed. The TDC receives a signal from a free-running DCO and a reference signal, and measures the time difference between the DCO and reference signals. The calibration unit receives and processes data samples output from the TDC and generates a calibration lookup table in which each TDC output value has a calibration value. The calibration lookup table may be used for post-distortion. For each TDC output level the corresponding calibration value from the lookup table may be added to the output of the TDC for correction.

Methods and apparatus for generating phase-shifted clock signals from a reference clock, connecting the phase-shifted clock signals to a counter module so that the phase-shifted clock signals change values in counters in the counter module, and combining the values in the counters to generate an output signal corresponding to an amount of time. One or more events can be detected at a time corresponding to the output signal. In embodiments, pulses can be transmitted and received at a measure time to evaluate connected devices.

A delay circuit with multiple dependencies on various environmental parameters is disclosed. The delay circuit is configured to receive an input signal. The delay circuit includes a first circuit configured to generate a first amount of delay, wherein the first amount of delay has a direct relationship to a first environmental parameter. The delay circuit also includes a second circuit configured to generate a second amount of delay such that the second amount of delay has an inverse relationship to a second environmental parameter. The delay circuit is configured to generate a delayed output signal based on the first and second amounts of delay generated by the first and second circuits.

A circuit includes a period calculator and a pulse width calculator. The period calculator is configured for receiving a first predetermined digital code and a second predetermined digital code, and for calculating a first calculated period value according to the first predetermined digital code, and calculating a second calculated period value according to the second predetermined digital code. The first predetermined digital code has a first predetermined period value, and the second predetermined digital code has a second predetermined period value. The pulse width calculator is configured for receiving a predetermined pulse width, and calculating a first pulse width code corresponding to the predetermined pulse width according to the first predetermined period value, the second predetermined period value, the first calculated period value, the second calculated period value and the predetermined pulse width.

A method for measuring parameters of an analog signal to determine times at which the analog signal (S) crosses predetermined voltage thresholds (V.sub.A, V.sub.B, V.sub.C, V.sub.D), the method comprising the steps of: splitting the analog signal (S) into a number of interim signals (S.sub.A, S.sub.B, S.sub.C, S.sub.D), the number of the interim signals corresponding to the number of the preset voltage thresholds (V.sub.A, V.sub.B, V.sub.C, V.sub.D); providing an FPGA system (10) comprising differential buffers (11 A, 11 B, 11 C, 11 D) with outputs connected to a number of sequences (20A, 20B, 20C, 20D) of delay elements (21, 22, 23), the number of sequences of delay elements corresponding to the number of the preset voltage thresholds (V.sub.A, V.sub.B, V.sub.C, V.sub.D); inputting, to an input of each differential buffer (11 A, 11 B, 11 C, 11 D), one interim signal (S.sub.A, S.sub.B, S.sub.C, S.sub.D) and a reference voltage corresponding to a particular preset voltage threshold (V.sub.A, V.sub.B, V.sub.C, V.sub.D); reading, by means of vector generators (31 A, 31 B, 31 C, 31 D), assigned separately to each of the sequences (20A, 20B, 20C, 20D) and connected to a common clock signal (CLK), current values of output signals of each of the delay elements (21, 22, 23) in the particular sequence (20A, 20B, 20C, 20D) at the same moment for all vector generators and providing these values as sequence output vectors (W.sub.A, W.sub.B, W.sub.C, W.sub.D); and determining times at which the analog signal (S) crosses the predetermined voltage thresholds (V.sub.A, V.sub.B, V.sub.C, V.sub.D) on the basis of the values of the sequence output vectors (W.sub.A, W.sub.B, W.sub.C, W.sub.D) and the delays introduced by the delay elements (21, 22, 23).