Full Automatic Notch Generation in Noise Spectrum of Pulse Coding Controlled Switching Converter

This paper proposes an EMI spread spectrum technology with automatic setting the notch frequency using the pulse coding controlled method of the DC-DC switching converter for the communication equipment. This proposed EMI spread spectrum technique does not distribute the switching noise into some specified frequency bands. The notch in the spectrum of the switching pulses is represented by the Pulse Width Coding (PWC) method. Notch frequency F
_n
is automatically set to the frequency of the received signal by adjusting the clock frequency F
_ck
using the equation F
_n
= (N + 0.5)F
_ck
. Here N is an integer. We have confirmed with simulation that the proposed technique is effective for EMI reduction and notch generation.