Contents I. Introduction
In the digital analog mixed signal chip, there is a need for a fully integrated clock signal generation circuit with high frequency accuracy [1] and high frequency stability, which can produce a clock signal that hardly changes with the ambient temperature, power supply voltage and process. In order to generate an accurate clock signal, the conventional method is to use an off-chip crystal oscillator as the clock generator, but this requires a corresponding crystal oscillator drive circuit inside to cooperate, which greatly increases the system cost. So, we can use oscillator to provide a reference clock to the sequential circuit [2].
