Texas Instruments Corporation

Jiankun Hu

Shailesh Ganapat Ghotgalkar

Wei Fu

Venkatseema Das

Visvesvaraya Appala Pentakota

Shagun Dusad

William J Bright

Mark B Weaver

William Bright

Mark Baxter Weaver

A phase-locked loop (PLL) includes a phase-frequency detector (PFD) having a first PFD input, a second PFD input, and a PFD output. The PFD is configured to generate a first signal on the PFD output. The first signal comprises pulses having pulse widths indicative of a phase difference between signals on the first and second PFD inputs. A low pass filter (LPF) has an LPF input and an LPF output. The LPF input is coupled to the PFD output. A flip-flop has a clock input and a flip-flop output. The clock input is coupled to the LPF output. A lock-slip control circuit is coupled to the flip-flop output and to the first PFD input. The lock-slip control circuit is configured to determine phase-lock and phase-slip based at least in part on a signal on the flip-flop output.

Phase-locked loop slip detector

A system (and associated method) includes an input flip-flop, a counter, and a clock tree. The input flip-flop includes a clock input terminal configured to be coupled to a device clock, or a clock generated from a phase-locked loop, and a data input terminal configured to be coupled to a first reference signal. The input flip-flop is configured to use the device clock to latch the reference signal to produce a latched reference signal. The counter is configured to count pulses of the device clock starting upon detection of the latched reference signal and to output a second reference signal comprising a pulse for every L pulses of the device clock. The clock tree is configured to divide down the device clock to generate a first output clock. The clock tree is configured to be synchronized by a pulse of the second reference signal.

Counter-based SYSREF implementation

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Jiankun Hu