The D.C. loop-gain of PWM voltage regulators

Abstract

The open-loop-gain of PWM voltage regulators at f = 0 can be expressed by simple formulae that are derived in this paper by means of charge and energy balances and the Campbell theorem. The three basic circuit topologies (Buck, Boost, Buck-Boost) are analysed both in the conventional duty-cycle control mode and in the current control mode. As each circuit can work either in the continuous or in the discontinuous conduction mode, a total of twelve formulae emerge. The effect of the slope compensation in the continuous current- mode is also discussed.