A Low-Noise Frequency Synthesizer Using Multiphase Generation and Combining Tech

Abstract

A ring oscillator (RO)-based low-noise frequency synthesizer is presented. Phase noise degradation caused by jitter accumulation in conventional RO-based synthesizers is alleviated by increasing the update rate. T o this end, multiple phases of the crystal oscillator (XO) output are generated and edge combined to produce a clock at an integer multiple of the XO frequency, which is then used as a reference clock to a conventional injection-locked clock multiplier that generates a low-noise high-