A −91 dB THD+N, Class-D Piezoelectric Speaker Driver Using Dual Voltage/Current Feedback for Resistor-Less LC Resonance Damping

Abstract

This article presents a Class-D audio amplifier for capacitive piezoelectric speaker loads. Employing a dual voltage feedback (VFB)/current feedback (CFB) topology, the amplifier is capable of damping LC resonance without using an external damping resistor, therefore reducing system power consumption, cost, and size. Additional power savings are achieved by using a push-pull (PP)-modulated output stage. To mitigate linearity degradation due to the mismatch of the feedback resistors, they are dynamically matched by employing choppers. The prototype, taped out in a BCD 180-nm process, can drive up to 4 µF load with a peak current of 4.4 A while achieving an idle power consumption of 122 mW and a peak THD+N of −91 dB.

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

“…Various power stage classes try to excel in one or both of these two aspects: Class-A stages offer superior linearity at the expense of efficiency; Class-B stages improve on efficiency but suffer from crossover distortion, while Class-AB topologies stay in between Class-A and Class-B in the efficiency metric. Switching output stages like Class-D and its variants, like Class-E (used mostly for RF applications [2]), feature very high power efficiency [3], [4], but lack in linearity compared to their non-switching counterparts.…”