文档介绍：High efficiency and low distortion switching power
amplifier for hearing aids
C.-,W.-.-
Abstract: A high efficiency and low distortion switching power amplifier is proposed. This circuit
is designed for micropower low-voltage hearing aids. The experimental results show that the
proposed circuit has % total harmonic distortion and 90% power efficiency while the .
output bias current ( for RL ¼ 600 O)is19mA at V supply voltage.
1 Introduction switching mode to improve the efficiency. Figure 2
shows the detailed circuit. The supply voltage is V.
In recent years, power amplifiers have e important The input stage includes a pseudo differential amplifier
in low-voltage low-power audio devices, especially for ðAvÞ, a Schmitt trigger (SCH) and a feedback loop.
portable and consumer electronics, including hearing aids. The output stage includes a full-bridge buffer and an
In battery powered portable consumer electronic appli- external low-pass filter (LPF) outside the IC chip. Ideally,
cations, the reduction of supply current results in longer the external lossless LC low-pass filter does not dissipate
run-time. power.
A persistent problem with power amplifiers is the The pseudo differential amplifier amplifiers the audio
distortion-power efficiency trade-off. In a conventional input signal and then the signal is passed through the
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