High efficiency class db power amplifier

Abstract

A method and circuitry for amplifying an input signal. First, second and third input signals are provided with the third input signal being the average of the first and second input signals. A ramp signal is provided using the third input signal as the ramp base signal and the first and second signals are compared with said ramp signal to provide an output responsive to only one of the first and second signals when the ramp signal and one of the first and second signals are equivalent. A load is driven in response to the output. In addition, an error signal can be provided by comparing the output with the first and second input signals and altering the first and second input signals as a result of comparing the output with the first and second input signals. The output is a function of the value of the ramp signal when the ramp signal and one of said first and second signals are equivalent. The comparison is provided by first and second comparators and the ramp signal is provided by storing the third input signal on a capacitor and periodically applying the signal on the capacitor enhanced by a current from a current source to provide the ramp to the capacitor and then to the comparators and concurrently applying to the comparators the first and second input signals.