Small-signal, low-frequency analysis of a buck type PWM conductance controller

Abstract

The small-signal, low-frequency control-voltage-to-output voltage transfer function of a buck cell utilizing the PWM (pulse width modulation) conductance control principle is derived, and its dependence on different circuit parameters is established. A numerical application shows close agreement with previously published data. The results obtained are used to compare the PWM conductance controller to its current-mode control counterpart utilizing a linear compensating ramp. Precise and comprehensive indications are given as to how the analysis applied can be used to investigate the dynamic loading imposed by the PWM conductance control cells on their input filters. The goal is to demonstrate the simplicity of the PWM conductance control principle's dynamic analysis when the method of characteristic coefficients is applied.<>