TEXAS A&M UNIVERSITY

Department of Electrical and Computer Engineering

College Station, Texas 77843-3128

TEL (409) 845-7498 FAX (409) 845-7161

http://amsc.tamu.edu

S E M I N A R

Room 105D ZEC

Thursday, Jaunuary 17, 2008 3:55 - 5:10 P.M.

A Low Power Class-AB 16W Headphone Driver Capable of Handling Wide Range of Load Capacitance

by

Vijay Dhanasekaran

Texas A&M University

Analog and Mixed Signal

Abstract: A versatile low power headphone driver that can be used in a variety of portable electronic devices is desirable for compatibility and design cycle time reasons. Several multistage amplifier compensation schemes that achieve high power efficiency for large capacitive loads were recently published. However, little attention has been paid to the problem of maintaining stability under large load variations. A simplified analysis of 3-stage amplifier compensation that allows easy modeling of load variations effects will be presented. This will be used to derive a new load-capacitance-aware compensation scheme. Design of a class-AB 16 headphone driver in 0.13m CMOS technology using this scheme will be shown. The driver can handle 1pF to 22nF capacitive load while consuming as low as 1.2mW of quiescent power. It delivers a maximum RMS power of 20mW to the load with -84.8dB THD and 92dB SNR. It occupies 0.1mm2 area.

Vijay Dhanasekaran received B.E. degree from P.S.G. College of technology, India in 1999. He was with Broadband Silicon Technology Center, Texas Instruments, Bangalore, India between 2000 and 2003. Since August 2003, he is working towards the Ph.D. degree at Texas A&M University. His research interests include active filters, line drivers, audio interface amplifiers and delta-sigma ADCs. He has authored/co-authored 3 refereed journal publications and holds the US patents 6653711, 7239195 and 7259627.