In generating a mask signal used to recover a clock signal embedded in an interface signal, the mask signal may be generated by comparing a plurality of comparison signals, generated by delaying a plurality of mask rising signals by a predetermined time, with the clock signal and selecting one mask rising signal used to generate a comparison signal close to one portion of the clock signal from among the plurality of mask rising signals.

In accordance with an embodiment, a ring oscillator includes a plurality of stages coupled in a ring configuration, where stage of the plurality of stages has an input node coupled to an output node of a previous stage of the plurality of stages. Each stage of the plurality of stages includes: a ring oscillator transistor having a control node coupled to the input node, and a load path coupled to the output node; a direct injection circuit having a load path coupled between the control node of the ring oscillator transistor and the output node, and a control node coupled to a first oscillator input node; and a tail injection circuit having a load path coupled between the output node and a first power supply node, and a control node coupled to a second oscillator input node.

This application is directed to an electronic device including a phase locked loop (PLL) circuit. The PLL includes a voltage-controlled oscillator (VCO) and the PLL is configured to generate a plurality of periodic signals having a first frequency. Optionally, the periodic signals are equally separated in phase to cover an entire period cycle of the first frequency. The electronic device includes a first multiplexer coupled to the PLL, the first multiplexer being external to the PLL. The first multiplexer configured to receive a first selection signal, select a first periodic signal of the plurality of periodic signals based on the first selection signal, and provide the first selected periodic signal to a first clock-driven circuit that is distinct from the PLL. The electronic device further includes a controller circuit coupled to the first multiplexer, the controller circuit being configured to provide the first selection signal to the first multiplexer.

In described examples, a storage cell ring includes circularly coupled storage cells. Each storage cell includes a respective capacitor for generating a respective integrated voltage responsive to a respective duration a respective storage cell is selected, a respective thresholding converter for generating a respective thresholded signal for indicating whether the respective integrated voltage has crossed a threshold, and respective selection circuitry configured to generate a respective select signal responsive to select signals generated by a respective adjacent storage cells. The ring is coupled to an analog quantifier for generating a conversion value responsive to the generated respective integrated voltage and a respective select signal. The ring is coupled to a loop counter for generating a loop count value responsive to changes of values of at least some of the respective thresholded signals. The conversion value and the loop count value can comprise a time measurement.

A closed loop transmitter (Tx) calibration system is disclosed. The closed loop Tx calibration system comprises a transmitter circuit configured to generate a Tx output signal at a Tx output frequency based on a Tx local oscillator (LO) signal. The closed loop Tx calibration system further comprises a loop back (LPBK) receiver circuit coupled to the transmitter circuit and configured to downconvert the Tx output signal at the Tx output frequency to form an LPBK baseband signal at an LPBK intermediate frequency (IF), based on an LPBK LO signal. In some embodiments, the LPBK IF frequency is different from zero. In some embodiments, the closed loop Tx calibration system further comprises an LO generation circuit configured to generate the Tx LO signal and the LPBK LO signal from a single phase locked loop (PLL) source, based on utilizing a digital to time converter (DTC) circuit.

This application is directed to an electronic device including a phase locked loop (PLL) circuit. The PLL includes a voltage-controlled oscillator (VCO) and the PLL is configured to generate a plurality of periodic signals having a first frequency. Optionally, the periodic signals are equally separated in phase to cover an entire period cycle of the first frequency. The electronic device includes a first multiplexer coupled to the PLL, the first multiplexer being external to the PLL. The first multiplexer configured to receive a first selection signal, select a first periodic signal of the plurality of periodic signals based on the first selection signal, and provide the first selected periodic signal to a first clock-driven circuit that is distinct from the PLL. The electronic device further includes a controller circuit coupled to the first multiplexer, the controller circuit being configured to provide the first selection signal to the first multiplexer.

An apparatus and method are provided. The apparatus includes a phase locked loop (PLL) configured to generate a reference signal; a sub-sampling PLL (SS-PLL) connected to the PLL and configured to sub-sample the reference signal; and a first pre-charge circuit connected to the SS-PLL and configured to allow an output voltage of the SS-PLL to transition to an operating voltage to indicate that a difference between two voltage inputs is zero on average.

A ring oscillator-based analog-to-digital converter (ADC). The ring oscillator-based ADC includes a ring oscillator and a transition detector. The ring oscillator may include a set of inverters coupled in a ring wherein an output of an inverter is coupled to an input of a successive inverter in the ring. The transition detector is configured to detect transitions of outputs of the inverters by comparing outputs of two separate inverters at two consecutive time instances. The transition detector may include two sets of registers configured to store outputs of the set of inverters at two consecutive time instances, respectively, and a set of comparators configured to compare the outputs stored in the two sets of registers. Each comparator may be configured to compare an output of one inverter at a first time instance and an output of another inverter at a second time instance.

Disclosed is a receiver circuit comprising an analog-to-digital converter (ADC) circuit having an analog input, a clock input, and a digital output, and a clock divider circuit having a reference clock input and a phase selector input, and having a clock output coupled to the clock input of the ADC circuit. The clock divider circuit is configured to divide a reference clock signal coupled to the reference clock input at a reference clock frequency, to produce a clock output signal at an ADC clock frequency, at the clock output, such that the reference clock frequency is an integer multiple N of the ADC clock frequency. The clock divider circuit is further configured to select from among a plurality of selectable phases of the clock output signal, responsive to a phase selector signal applied to the phase selector input.

A method and apparatus of generating precision phase skews is disclosed. In some embodiments, a phase skew generator includes: a charge pump having a first mode of operation and a second mode of operation, wherein the first mode of operation provides a first current path during a first time period, and the second mode of operation provides a second current path during a second time period following the first time period; a sample and hold circuit, coupled to a capacitor, and configured to sample a voltage level of the capacitor at predetermined times and provide an output voltage during a third time period following the second time period; and a voltage controlled delay line, coupled to the sample and hold circuit, and having M delay line stages each configured to output a signal having a phase skew offset with respect to preceding or succeeding signal.