US Patent 11005480 Phase locked loop device and clock generation method

A phase locked device includes a digital controlled oscillator circuit, a clock signal generator circuitry, a time to digital converter circuit, and a logic control circuit. The digital controlled oscillator circuit is configured to generate a first clock signal in response to a plurality of digital codes. The clock signal generator circuitry is configured to generate a plurality of second clock signals according to the first clock signal, and to select a third clock signal and a fourth clock signal from the plurality of second clock signals according to a selection signal, in order to generate an output signal. The time to digital converter circuit is configured to detect a delay difference between the output signal and a reference signal, in order to generate the plurality of digital codes. The logic control circuit is configured to generate the selection signal according to the plurality of digital codes.