Phase-shift self-oscillating class-D audio amplifier with multiple-pole feedback filter

Hyungjin Lee; Hyunsun Mo; Wanil Lee; Mingi Jeong; Jaehoon Jeong; Daejeong Kim

doi:10.1587/elex.8.1354

LETTER

Phase-shift self-oscillating class-D audio amplifier with multiple-pole feedback filter

Hyungjin Lee, Hyunsun Mo, Wanil Lee, Mingi Jeong, Jaehoon Jeong, Daejeong Kim

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Keywords: PWM, class-D amplifier, self-oscillation, delta-sigma modulation

JOURNAL FREE ACCESS

2011 Volume 8 Issue 16 Pages 1354-1360

DOI https://doi.org/10.1587/elex.8.1354

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Abstract

A self-oscillating class-D audio amplifier employing a multiple-pole feedback filter is introduced intended for portable multimedia devices. As the oscillation is based on the Barkhausen's criterion, the signal-dependent oscillation frequency is of great concern. Employing higher-order filters contributes to the stable oscillation frequency depending on the input amplitude as well as improves PSRR and THD. The concept is revealed comparatively with other works, and a design implemented in a 0.35um CMOS process under 3.3V supply is proposed and verified.

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