Notch Frequency Generation Methods in Noise Spread Spectrum for Pulse Coding Switching DC-DC Converter

Abstract

This paper introduces two pulse coding control methods for generating notch frequency automatically in noise spread spectrum for switching DC-DC converters; these are based on our previously proposed method. Our two methods here generate the notch frequency Fn automatically according to the received frequency Fin. The first one is a constant frequency PWM-controlled buck DC-DC converter where the clock frequency and coding pulse width are automatically set according to the frequency of the received signal to generate notch characteristics. The second one is a pulse frequency modulation (PFM) pulse coding DC-DC converter which generates a composite notch characteristic where both the constant pulse width and the periodic modulation coding pulse width are automatically matched with input frequency Fin. Our simulation results show that the transient response is fast and the output voltage overshoot is small.