A low-distortion output stage with improved stability for monolithic power amplifiers

Author

Seevinck, Evert ; De Jager, Wim ; Buitendijk, Piet

Author_Institution

Philips Res. Labs., Eindhoven, Netherlands

Volume

23

Issue

3

fYear

1988

fDate

6/1/1988 12:00:00 AM

Firstpage

794

Lastpage

801

Abstract

A low-distortion class AB output stage with improved stability suitable for monolithic power amplifiers (P/sub 0/>or=40 W) is described. The concept has been verified on a 12-W breadboard version as well as on a partly integrated prototype, and is supported by computer simulations for P/sub 0/>or=40 W A biasing control law which guarantees predictable conduction of both output transistors at all times is implemented. This reduces crossover distortion and allows the customary quasi-p-n-p compound transistor to be eliminated, thus also improving stability. Linearity is improved by use of local negative feedback. Phase margin is improved by application of high-frequency feedforward. Measured phase margin is around 60 degrees and total harmonic distortion for a load of 7 Omega is about -80 dB at 20 kHz.<>

Keywords

audio-frequency amplifiers; bipolar integrated circuits; feedback; linear integrated circuits; operational amplifiers; power amplifiers; stability; 40 W; biasing control law; bipolar IC; class AB; high-frequency feedforward; local negative feedback; low-distortion output stage; monolithic power amplifiers; operational amplifiers; stability; Circuit stability; Computer simulation; Distortion measurement; Linearity; Negative feedback; Operational amplifiers; Phase measurement; Pollution measurement; Power amplifiers; Virtual prototyping;

fLanguage

English

Journal_Title

Solid-State Circuits, IEEE Journal of

Publisher

ieee

ISSN

0018-9200

Type

jour

DOI

10.1109/4.320

Filename

320