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

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 $\mu \text{F}$ 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.