The pulse generated by the clock circuit is generally generated by the oscillator, there are many kinds of oscillators, the most commonly used is the quartz oscillator, which is often said that the crystal oscillator. A clock circuit is a circuit that produces oscillations as accurate as a clock. Any work is done in chronological order. The circuit used to produce this time is the clock circuit. The clock circuit is generally composed of a crystal oscillator, a crystal vibration control chip and a capacitor. Clock circuit is widely used, such as computer clock circuit, electronic watch clock circuit and MP3MP4 clock circuit