A -109.1 dB/-98 dB THD/THD+N Chopper Class-D Amplifier with >83.7 dB PSRR Over the Entire Audio Band

Abstract

This paper reports a chopper Class-D audio amplifier that obtains high PSRR over the entire audio band. A chopping scheme is proposed to minimize intermodulation distortion between pulse-width modulation (PWM) and chopping in the audio band. A high-voltage chopper is developed to handle a 14.4 V PWM signal. Timing matching techniques are proposed to minimize chopping nonidealities which ensure good PSRR and THD. Fabricated in a 180nm BCD process, the prototype obtains a PSRR >109 dB at 217 Hz and >83.7 dB over the entire audio band. It also achieves −109.1 dB/−98 dB THD/THD+N and can deliver a maximum of 13 W to an 8-Ω load.

A Chopper Class-D Amplifier for PSRR Improvement Over the Entire Audio Band

“…The prototype achieves a peak efficiency of 93%. The slight improvement from that reported in [14] is likely due to the improved thermal conductivity of the test assembly.…”

“…The amplifier is loaded with 8 Ω in series with 44 μH, and its output is measured by an Audio Precision 1 The PDK does not include mismatch model for the 2 LDMOS devices in the level shifter, so their mismatch contribution is not included. 2 The results reported here are obtained from a silicon revision of [14], which fixes a bond pad issue in [14] that caused the THD to degrade at large signal levels. APx555 audio signal analyzer.…”

“…A 14.4 V Class-D amplifier prototype is designed in a 180 nm BCD process, which achieves a THD of −109.1 dB. The This paper is an extension of [14] and is organized as follows. Section II analyzes the causes of PSRR limitations in conventional Class-D amplifiers.…”

A 121.4dB DR, -109.8dB THD+N Capacitively-Coupled Chopper Class-D Audio Amplifier

“…Due to the sensitivity of the human ear, a large dynamic range (DR) is desired, and audio DACs with up to 130dB DR are commercially available [1]. However, the DR of the CDAs they drive is typically much lower [2][3][4], mainly due to the thermal noise introduced by the input resistors of their resistive feedback networks. Reducing this resistance is difficult, as it reduces the CDA's input impedance and increases the required loop-filter capacitance.…”

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

“…All RC networks are made 2-bit trimmable to account for process spread, and share the same trim code. Core LV devices (1.8V) are used for CH IN and CH Vir , whereas HV LDMOS devices are used for CH HV [6].…”