An Analysis of THD in Class D Amplifiers

Huey Chian Foong; Meng Tong Tan;IEEE Asia Pacific Conference on Circuits and Systems, 2006. APCCAS 2006.

Page(s):724 - 727.4-7 Dec. 2006

指導教授：易序忠學 生：楊正元

國立彰化師範大學積體電路設計研究所

Outline

THD & PSRR

Open-loop Class D amplifier

2nd-order closed-loop Class D amplifier

Dual-loop Class D amplifier

THD & PSRR

THD （ Total Harmonic Distortion ） （ ％ ） Lower is better ＜ 10 ％

PSRR （ Power Supply Rejection Rate ） （ dB ） Higher is better

Open-loop Class D amplifier

2nd-order closed-loop Class D amplifier

A linear model of the 2nd-order closed-loop Class D amplifier

Transfer function

Parameter

GPWM is determined by the ratio of the power supply voltage over the amplifier of the carrier.

GPWM is less than 5 for a larger input dynamic range and signal-to-noise ratio.

Parameter

H1 is approximately equal to –Rfb/R1.

H1 is the higher is the better.

The gain and bandwidth of the integrator has to be optimized to improve the PSRR and THD.

Frequency respond of the 2nd-order integrator

A dual-loop Class D amplifier based on 2nd-order integrator

Dual-loop transfer function

Loop-gain frequency response with dual loop feedback

THD of a single-loop feedback Class D amplifier

THD of a dual-loop feedback Class D amplifier

The end.