A low THD clock-free Class-D audio amplifier with an increased damping resistor and cross offset cancellation technique

Author

Ying-Wei Chou ; Meng-Wei Chien ; Shin-Chieh Chen ; Ke-Horng Chen ; Ying-Hsi Lin ; Tsung-Yen Tsai ; Chen-Chih Huang ; Chao-Cheng Lee ; Zhih Han Tai ; Yi Hsuan Cheng ; Chi Chung Tsai ; Hsin-Yu Luo ; Shih-Ming Wang ; Long-Der Chen ; Cheng-Chen Yang ; Huang T

Author_Institution

Inst. of Electr. Control Eng., Nat. Chiao Tung Univ., Hsinchu, Taiwan

fYear

2014

fDate

1-5 June 2014

Firstpage

2680

Lastpage

2683

Abstract

An increased damping resistor (IDR) replaces high-order loop filter to simply reduce the total harmonic distortion (THD) of Class-D audio amplifier. Besides, cross offset cancellation (COC) technique minimizes the system offset voltage to avoid dc current flows to the speaker in the bridge tied load (BTL) structure. Furthermore, variable switching frequency characteristic in self-oscillating modulation spreads the electro-magnetic interference (EMI) impact out on the output frequency spectrum. Experimental results demonstrate that the proposed Class-D amplifier can deliver 0.55W to the 8Ω load with a 3.3V supply voltage with 150-nm CMOS process. The power efficiency is over 90% and the output THD is smaller than 0.01% (80dB).

Keywords

CMOS analogue integrated circuits; audio-frequency amplifiers; electromagnetic interference; harmonic distortion; resistors; BTL; CMOS process; COC technique; EMI impact; IDR; bridge tied load structure; cross offset cancellation technique; dc current; electromagnetic interference; high-order loop filter; increased damping resistor; low THD clock-free class-D audio amplifier; output frequency spectrum; power 0.55 W; resistance 8 ohm; self-oscillating modulation; size 150 nm; system offset voltage minimization; total harmonic distortion; variable switching frequency characteristic; voltage 3.3 V; CMOS integrated circuits; Clocks; Frequency modulation; Generators; Power harmonic filters; Switching frequency; Class-D audio amplifier; audio amplifier; clock-free; mobile application; offset cancellation; self-oscillating;

fLanguage

English

Publisher

ieee

Conference_Titel

Circuits and Systems (ISCAS), 2014 IEEE International Symposium on

Conference_Location

Melbourne VIC

Print_ISBN

978-1-4799-3431-7

Type

conf

DOI

10.1109/ISCAS.2014.6865725

Filename

6865725