Research on Clock Circuit Electromagnetic Emission Test and Suppression

Abstract

Clock circuit is an important part of PCB, which is usually composed of crystal oscillator, crystal oscillator control chip and capacitor. Electromagnetic emission generated by clock circuit is one of the main interference sources of electronic equipment. According to the different transmission paths, electromagnetic interference caused by clock circuit usually includes conduction interference and radiation interference. When the electromagnetic emission generated by the clock circuit reaches a certain degree, it may affect the electromagnetic compatibility of electronic equipment. In this paper, by analyzing the frequency spectrum characteristics of the clock signal, the difference of the frequency spectrum of the clock signal under different parameters is compared, and the electromagnetic emission test method is given. On this basis, when the EMI suppression method of clock circuit is studied, a series of EMC design methods of clock circuit are summarized, and the application of spread spectrum technology in clock circuit is proposed.