Embodiments described herein provide an electronic device, which includes a first oscillator configured to output a first clock signal, and a second oscillator that is co-located with the first oscillator on the electronic device. The electronic device further includes a first bandpass filter configured to filter a first input signal derived from the first clock signal received through a negative feedback loop, and to output a first signal component corresponding to the first signal spur. The electronic device further includes a signal reconstruction circuit configured to receive the first signal component and to combine the first signal component into a control signal for the first oscillator, and to feed the control signal combined with the first signal component to the first oscillator to mitigate the first signal spur exhibited in the first clock signal.

A system and a method for hitless clock switching are provided. In the system, a sampling circuitry group samples a primary reference clock signal and a secondary reference clock signal to obtain first and second sampling information, respectively. A phase detector group obtains a phase difference between the primary and secondary reference clock signals with the first and second sampling information. A compensator group adds the phase difference to a phase of the secondary reference clock signal to obtain a backup reference clock signal. When the primary reference clock signal is abnormal or missing, the signal selector determines the backup reference clock signal as a target reference clock signal and sends it to a phase-locked loop. The phase-locked loop performs loop control on the target reference clock signal, thereby implementing hitless switching of reference clock signals.

A phase-locked loop (PLL) includes a selection circuit including a plurality of inputs, each input to receive a separate reference clock. A programmable reference clock divider divides down the reference clock selected by the selection circuit to generate a divided down reference clock. A feedback clock divider divides down an output clock from the PLL to generate a feedback clock. A time-to-digital converter (TDC) generates a digital output value based on a phase difference between the divided down reference clock and the feedback clock. A circuit including a finite state machine, causes, responsive to an indication to change reference clocks, the reference clock divider and the feedback clock divider to be held in a reset state, the divide ratio of the reference clock divider to be modified, and then to release the reset state.

A phase-locked loop (PLL) includes a selection circuit including a plurality of inputs, each input to receive a separate reference clock. A programmable reference clock divider divides down the reference clock selected by the selection circuit to generate a divided down reference clock. A feedback clock divider divides down an output clock from the PLL to generate a feedback clock. A time-to-digital converter (TDC) generates a digital output value based on a phase difference between the divided down reference clock and the feedback clock. A circuit including a finite state machine, causes, responsive to an indication to change reference clocks, the reference clock divider and the feedback clock divider to be held in a reset state, the divide ratio of the reference clock divider to be modified, and then to release the reset state.

Apparatuses and methods for providing frequency divided clocks are described. An example apparatus includes a first circuit configured to provide a first intermediate clock responsive, at least in part, to a first input clock, the first intermediate clock being lower in frequency than the first input clock and further includes a second circuit configured to provide a second intermediate clock and a third intermediate clock responsive, at least in part, to a second input clock, the second intermediate clock being complementary to the third intermediate clock and lower in frequency than the second input clock. The apparatus further includes a third circuit configured to select and provide as an output clock one of the second and third intermediate clocks responsive, at least in part, to the first and second intermediate clocks.

Apparatuses and methods for providing frequency divided clocks are described. An example apparatus includes a first circuit configured to provide a first intermediate clock responsive, at least in part, to a first input clock, the first intermediate clock being lower in frequency than the first input clock and further includes a second circuit configured to provide a second intermediate clock and a third intermediate clock responsive, at least in part, to a second input clock, the second intermediate clock being complementary to the third intermediate clock and lower in frequency than the second input clock. The apparatus further includes a third circuit configured to select and provide as an output clock one of the second and third intermediate clocks responsive, at least in part, to the first and second intermediate clocks.

Apparatuses and methods for providing frequency divided clocks are described. An example apparatus includes a first circuit configured to provide a first intermediate clock responsive, at least in part, to a first input clock, the first intermediate clock being lower in frequency than the first input clock and further includes a second circuit configured to provide a second intermediate clock and a third intermediate clock responsive, at least in part, to a second input clock, the second intermediate clock being complementary to the third intermediate clock and lower in frequency than the second input clock. The apparatus further includes a third circuit configured to select and provide as an output clock one of the second and third intermediate clocks responsive, at least in part, to the first and second intermediate clocks.

An apparatus and a method are disclosed for synchronizing clock signals distributed within a wireless device. In some embodiments, a local oscillator (LO) clock signal is buffered and distributed to two or more transceivers within the wireless device. Each transceiver may include a configurable clock divider to divide the distributed LO clock signal and generate an output clock signal. A phase detector compares output clock signals from each of the configurable clock dividers and generates an output signal in accordance with a determined phase difference. The phase detector output signal may cause at least one of the configurable clock dividers to modify its respective output clock signal, and thereby synchronize output clock signals between different configurable clock dividers. In some embodiments, a clock signal from a configurable clock divider may be modified (shifted) by approximately 90 or 180 degrees.

Methods, apparatuses, and systems are described related a data receiver circuit having a pair of offset edge samplers to sample a data signal, at an edge sampling time between data samples, with respect to different reference levels. A clock-data recovery (CDR) circuit of the receiver circuit may determine an A-count that corresponds to a number of times the signal level of the data signal at the edge sampling time is between the reference levels of the offset edge samples to provide a signal integrity metric for the receiver circuit. The CDR circuit may dynamically update its settings based on the A-count.

Apparatuses and methods for providing frequency divided clocks are described. An example apparatus includes a first circuit configured to provide a first intermediate clock responsive, at least in part, to a first input clock, the first intermediate clock being lower in frequency than the first input clock and further includes a second circuit configured to provide a second intermediate clock and a third intermediate clock responsive, at least in part, to a second input clock, the second intermediate clock being complementary to the third intermediate clock and lower in frequency than the second input clock. The apparatus further includes a third circuit configured to select and provide as an output clock one of the second and third intermediate clocks responsive, at least in part, to the first and second intermediate clocks.