US Patent 7598790 Clock synthesis using polyphase numerically controlled oscillator

A clock synthesis circuit includes a polyphase numerically controlled oscillator, an extraction circuit, and a clock signal generation circuit. The polyphase numerically controlled oscillator generates sets of periodic output signals. Each set of the periodic output signals represents a different phase of a periodic waveform signal. The extraction circuit extracts a most significant bit from each set of the periodic output signals of the polyphase numerically controlled oscillator to generate most significant bits. The clock signal generation circuit converts the most significant bits into a serial bit stream that serves as an output clock signal.