Noise spread spectrum with adjustable notch frequency in complex pulse coding controlled DC-DC converters

This paper proposes a novel EMI spread spectrum technology with the adjustable notch frequencies using a complex pulse coding method for the DC-DC switching converter. The notches in the spread spectrum of the switching pulse appear at the frequencies obtained from the theoretical equations using the parameters of coding pulses. In the PWC (Pulse Width Coding) method, the fundamental notch frequency is concerned with the pulse width difference between two coded pulses. In the complex PWPC (Pulse Width and Phase Coding) method, the notch frequency is calculated from the difference of the pulse width and phase. We have examined the theoretical notch frequency which is adjustable in the PWC controlled converter using the equation Fn=N/(W1-W2).