Active filter power dissipation reduction using improved op amp output stage

One way the power dissipation can be reduced is to dynamically switch the voltage supply to a lower voltage supply at instants where the output waveform is also low. This approach can be implemented using parallel or stacked class-B stages and has been dubbed the `class-G´ amplifier. Class-G amplifiers have been proposed for high-power use with resistive loads, and significant improvements in power efficiency have been demonstrated. The author shows that the class-G amplifier can also be beneficially applied to low-power op amp active filter circuits where the effective load impedances on the op amps are in general complex