Class-CTA: Concept and Theoretical Analysis of a High Linearity and Efficiency Power Stage Architecture

This work presents a power stage architecture that combines high-linearity with high-efficiency. The power stage is configured as a push-pull Class-A topology with two buck-converters providing its supply rails. The buck-converters continuously track the stage's output with a small constant margin, creating a minimum, constant voltage drop on the output devices; thus, the stage's efficiency is increased and its linearity is improved. Theoretical analysis of the topology and its feedback control are presented, while a design example is implemented and simulated in Cadence Spectre as proof-of-concept.