Open AccessA Class‐D Amplifier for a Digital Hearing Aid with 0.015% Total Harmonic Distortion Plus Noise
Author(s) -
Lee Dongjun,
Noh Jinho,
Lee Jisoo,
Choi Yongjae,
Yoo Changsik
Publication year - 2013
Publication title -
etri journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.295
H-Index - 46
eISSN - 2233-7326
pISSN - 1225-6463
DOI - 10.4218/etrij.13.0112.0852
Subject(s) - amplifier , electronic engineering , electrical engineering , noise (video) , engineering , audio power amplifier , delta sigma modulation , linear amplifier , total harmonic distortion , low noise amplifier , rf power amplifier , computer science , cmos , voltage , artificial intelligence , image (mathematics)
A class‐D audio amplifier for a digital hearing aid is described. The class‐D amplifier operates with a pulsecode modulated (PCM) digital input and consists of an interpolation filter, a digital sigma‐delta modulator (SDM), and an analog SDM, along with an H‐bridge power switch. The noise of the power switch is suppressed by feeding it back to the input of the analog SDM. The interpolation filter removes the unwanted image tones of the PCM input, improving the linearity and power efficiency. The class‐D amplifier is implemented in a 0.13‐μm CMOS process. The maximum output power delivered to the receiver (speaker) is 1.19 mW. The measured total harmonic distortion plus noise is 0.015%, and the dynamic range is 86.0 dB. The class‐D amplifier consumes 304 μW from a 1.2‐V power supply.