PAPER SESSION 1: INTEGRATION PERSPECTIVES
A Scalable Class D Audio Amplifier for Low Power Applications
Tony Forzley, Ralph Mason
Carleton
University, Ottawa, Ontario, Canada
This paper describes a class D amplifier topology with
digital input and a digital compensation loop filter to
improve linearity. The core of the system is a high
resolution hybrid multi-bit SigmaDelta-Pulse Width
Modulation (PWM) modulator without the need for
Dynamic Element Matching (DEM). Furthermore, high
frequency DSP algorithms to correct for PWM distortion
are not required. A system prototype based on a
FPGA and commercial 16b analog to digital converter
(ADC) validate the system design before implementation
in 0.13um CMOS. Measurement results at 1 kHz
yield a Total Harmonic Distortion (THD) better than
0.03% and greater than 30 dB of noise rejection. The
system is inherently scalable to deep submicron
processes due to its predominately digital architecture.
To reduce power consumption a low power ADC
design is presented.
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