A 120.9-dB DR Digital-Input Capacitively Coupled Chopper Class-D Audio Amplifier

This article presents a digital-input class-D amplifier (CDA) achieving high dynamic range (DR) by employing a chopped capacitive feedback network and a capacitive digital-to-analog converter (DAC). Compared with conventional resistive-feedback CDAs driven by resistive or current-steeringDACs, the proposed architecture eliminates the noise fromthe DAC and feedback resistors. Intermodulation between thechopping, pulsewidth modulation (PWM), and DAC samplingfrequency is analyzed to avoid negative impacts on the DRand linearity. Real-time dynamic element matching (RTDEM) is employed to address distortion due to mismatch in the DAC, while its inter symbol interference (ISI) is eliminated by deadbanding. The prototype, implemented in a 180-nm bipolar, CMOS, and DMOS (BCD) process, achieves 120.9 dB of DR and a peak total harmonic distortion plus noise (THD+N) of-111.2 dB. It candrive a maximum of 15/26 W into an 8-/4-Omega load with a peak efficiency of 90%/86%.