A low-voltage low-power fully-integratable front-end for hearing instruments

Author

Serdijn, Wouter A. ; van der Woerd, Albert C. ; Davidse, Jan ; Van Roermund, Arthur H M

Author_Institution

Fac. of Electr. Eng., Delft Univ. of Technol., Netherlands

Volume

42

Issue

11

fYear

1995

fDate

11/1/1995 12:00:00 AM

Firstpage

920

Lastpage

932

Abstract

The front-end of a universally applicable analog integrated circuit for hearing instruments is presented. This IC comprises the following functions: a microphone preamplifier, a pickup-coil preamplifler, a second-order high-pass filter and a second-order low-pass filter, both with a controllable cutoff frequency, and an input-controlled automatic gain control with an adjustable knee level. By applying a compression/expansion system and operating all the circuits in the current domain as much as possible, all these functions can be implemented in a single IC, without the need for external components. The test chip demonstrates operation down to 1.05 V and a current consumption between 120 and 175 μA. The full-custom chip area in a 2.5-μm BiCMOS process (using only vertical NPN´s and lateral PNP´s) amounts to 2.4 mm²

Keywords

BiCMOS analogue integrated circuits; active filters; analogue processing circuits; application specific integrated circuits; audio-frequency amplifiers; automatic gain control; biomedical electronics; hearing aids; high-pass filters; low-pass filters; preamplifiers; 1.05 V; 120 to 175 muA; 2.5 micron; BiCMOS process; adjustable knee level; analog integrated circuit; automatic gain control; compression/expansion system; controllable cutoff frequency; current domain operation; full-custom chip; hearing instruments; input-controlled AGC; low-voltage low-power front-end; microphone preamplifier,; monolithic IC; pickup-coil preamplifler; second-order high-pass filter; second-order low-pass filter; Analog integrated circuits; Auditory system; Circuit testing; Cutoff frequency; Gain control; Instruments; Knee; Low pass filters; Microphones; Preamplifiers;

fLanguage

English

Journal_Title

Circuits and Systems I: Fundamental Theory and Applications, IEEE Transactions on

Publisher

ieee

ISSN

1057-7122

Type

jour

DOI

10.1109/81.477203

Filename

477203