A delay circuit includes precharge and discharge transistors configured to receive an input signal. The delay circuit also includes a resistor coupled to the precharge transistor having a negative temperature coefficient to thereby form a node. A capacitive device and an inverter are coupled to the node. The inverter produces an output signal. Responsive to the input signal having a first polarity, the precharge transistor is configured to be turned on and the discharge transistor is configured to be turned off to thereby cause current to flow through the precharge transistor to the capacitive device to thereby charge the capacitive device. Responsive to the input signal having a second polarity, the precharge and discharge transistors are configured to change state to thereby cause charge from the capacitive device to discharge through the resistor and through the discharge transistor. The voltage on the node decays to a level which eventually causes the inverter's output to change state.

A method for operating a data interface circuit whereby calibration adjustments for data bit capture are made without disturbing normal system operation includes initially establishing, using a first calibration method where a data bit pattern received by the data interface circuit is predictable, an optimal sampling point for sampling data bits received by the data interface circuit, and during a normal system operation and without disturbing the normal system operation, performing a second calibration method where the data bit pattern received by the data interface circuit is unpredictable. The second calibration method determines an amount of a timing drift for received data bit edge transitions and adjusts the optimal timing point determined by the first calibration method to create a revised optimal timing point. The second calibration method samples fringe timing points associated with the transition edges of a data bit.

A method for operating a data interface circuit whereby calibration adjustments for data bit capture are made without disturbing normal system operation includes initially establishing, using a first calibration method where a data bit pattern received by the data interface circuit is predictable, an optimal sampling point for sampling data bits received by the data interface circuit, and during a normal system operation and without disturbing the normal system operation, performing a second calibration method where the data bit pattern received by the data interface circuit is unpredictable. The second calibration method determines an amount of a timing drift for received data bit edge transitions and adjusts the optimal timing point determined by the first calibration method to create a revised optimal timing point. The second calibration method samples fringe timing points associated with the transition edges of a data bit.

A temporal jitter analyzer analyzes temporal jitter and includes: a time delay controller; a time delay member; a delay measurement circuit; an edge generator in communication with the time delay member and that receives the delayed primary signal from the time delay member and produces a reference signal from the delayed primary signal; a decision circuit in communication with the edge generator and that: receives the reference signal from the edge generator; receives a detector signal; and produces a raw decision signal from the detector signal such that a value of the raw decision signal depends on the reference signal; and a decision circuit readout in communication with the edge generator and the decision circuit and that: receives the reference signal from the edge generator; receives the raw decision signal from the decision circuit; and produces a decision signal from the raw decision signal based on the reference signal.

A temporal jitter analyzer analyzes temporal jitter and includes: a time delay controller; a time delay member; a delay measurement circuit; an edge generator in communication with the time delay member and that receives the delayed primary signal from the time delay member and produces a reference signal from the delayed primary signal; a decision circuit in communication with the edge generator and that: receives the reference signal from the edge generator; receives a detector signal; and produces a raw decision signal from the detector signal such that a value of the raw decision signal depends on the reference signal; and a decision circuit readout in communication with the edge generator and the decision circuit and that: receives the reference signal from the edge generator; receives the raw decision signal from the decision circuit; and produces a decision signal from the raw decision signal based on the reference signal.

Multiphase signal generation circuitry receives input signals that are out-of-phase with one another by a quadrature delay (e.g., 90°), and generates output signals that are out-of-phase with one another by half of the quadrature delay. A first input signal may be provided to a first delay circuitry, which is then input to a first phase interpolator. The first delay circuitry is also input to second delay circuitry, which also generates an output that is input to the first phase interpolator. The first phase interpolator outputs a first output signal. The second delay circuitry is input to third delay circuitry, which in turn is input to a second phase interpolator with a second input signal that is out-of-phase with the first input signal by the quadrature delay. The second phase interpolator outputs a second output signal that is out-of-phase with the first output signal by the half of the quadrature delay.

Apparatus and methods for clock synchronization and frequency translation are provided herein. Clock synchronization and frequency translation integrated circuits (ICs) generate one or more output clock signals having a controlled timing relationship with respect to one or more reference signals. The teachings herein provide a number of improvements to clock synchronization and frequency translation ICs, including, but not limited to, reduction of system clock error, reduced variation in clock propagation delay, lower latency monitoring of reference signals, precision timing distribution and recovery, extrapolation of timing events for enhanced phase-locked loop (PLL) update rate, fast PLL locking, improved reference signal phase shift detection, enhanced phase offset detection between reference signals, and/or alignment to phase information lost in decimation.

A phase locked loop includes a pulse limiter between a phase frequency detector and a charge pump. The phase frequency detector generates and sends a clock pulse to the pulse limiter. The pulse limiter generates a first signal that indicates that the clock pulse is greater than a minimum pulse width of the phase frequency detector. The pulse limiter receives a pulse limiter buffer selection signal that selects one buffer of a plurality of buffers within the pulse limiter. The pulse limiter generates a second signal that indicates a truncated pulse width as the minimum pulse width of the phase frequency detector plus a delay period that is associated with the pulse limiter buffer selection signal. The pulse limiter truncates the clock pulse to the truncated pulse width and sends the truncated clock pulse to the charge pump.

A phase locked loop includes a pulse limiter between a phase frequency detector and a charge pump. The phase frequency detector generates and sends a clock pulse to the pulse limiter. The pulse limiter generates a first signal that indicates that the clock pulse is greater than a minimum pulse width of the phase frequency detector. The pulse limiter receives a pulse limiter buffer selection signal that selects one buffer of a plurality of buffers within the pulse limiter. The pulse limiter generates a second signal that indicates a truncated pulse width as the minimum pulse width of the phase frequency detector plus a delay period that is associated with the pulse limiter buffer selection signal. The pulse limiter truncates the clock pulse to the truncated pulse width and sends the truncated clock pulse to the charge pump.

Provided is an integrated circuit. The integrated circuit includes a plurality of clock generators configured to respectively generate a plurality of clock signals, a plurality of logic circuits configured to operate in synchronization with the plurality of clock signals, and controller circuitry configured to identify meta-stability information based on frequencies of the plurality of clock signals, and configured to control at least one clock generator so that at least one of the plurality of clock signals is randomly delayed in response to the meta-stability information.