Open-loop peak voltage feedforward control of PWM buck converter

DC and small-signal analyses are given for an open-loop buck pulse-width modulated (PWM) DC-DC converter with peak-voltage-modulation (PVM) feedforward control. A DC model is used to derive the DC input-to-output voltage transfer function taking into account parasitic components, such as the MOSFET on-resistance, diode forward resistance, and diode offset voltage. A small-signal model is used to derive the audio susceptibility and the input impedance. It is shown that ideally the audio susceptibility is zero and the input impedance is frequency independent and negative for the buck converter with PVM feedforward control.