1. An Analysis of THD in Class D Amplifiers
Huey Chian Foong; Meng Tong Tan;
IEEE Asia Pacific Conference on Circuits and Systems, APCCAS 2006.
Page(s): 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

2. Outline THD & PSRR Open-loop Class D amplifier
2nd-order closed-loop Class D amplifier
Dual-loop Class D amplifier

3. THD & PSRR THD （Total Harmonic Distortion） （ ％ ） Lower is better ＜10％
PSRR（Power Supply Rejection Rate）
（dB） Higher is better

4. Open-loop Class D amplifier

5. 2nd-order closed-loop Class D amplifier

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

7. Transfer function

8. 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.

9. 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.

10. Frequency respond of the 2nd-order integrator

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

12. Dual-loop transfer function

13. Loop-gain frequency response with dual loop feedback

14. THD of a single-loop feedback Class D amplifier

15. THD of a dual-loop feedback Class D amplifier

16. The end.