Digital controller for controlling output voltage under large variations in load and supply voltage

Abstract

There is provided a digital controller which can reduce a variation in output voltage as compared to the conventional digital controller at the time of abrupt changes in load and in input of a power amplifier. The digital controller is built in the power amplifier for supplying an output voltage vto a load and is equipped with a manipulated variable calculating unit which detects the output voltage vto calculate a manipulated variable ξand a signal generating unit which converts the manipulated variable ξinto a signal for making the power amplifier operate. A feedforward function from an equivalent disturbance qy caused by the variation in the load is replaced by a feedback function from the output voltage vand the manipulated variable ξ, thereby allowing a transfer characteristic from the disturbance qy to the output voltage vto result in a quadratic differential characteristic. Consequently, the variation in output voltage can be reduced as compared to the conventional controller at the time of the abrupt changes in the load and in the input of the power amplifier.