VERDI: an acoustically programmable and adjustable CMOS mixed-mode signal processor for hearing aid applications

A CMOS mixed-mode fully-differential signal processor (VERDI), that constitutes the core of a hearing aid system, is introduced. Its characteristics (frequency response, compression level, and output sound pressure level) are wireless controlled by means of dual tone multi-frequency (DTMF) encoded signals transmitted by an external unit. A system description is provided, and the implementation and experimental results of the key components (preamplifier, antialiasing filter, automatic gain control, filter section, output amplifier, and DTMF receiver/decoder) are covered in more detail. The circuit has been fabricated in a conventional 1.2 /spl mu/m CMOS n-well process and operates from a single 1.3 V battery, although a dc/dc converter is required. It consumes typically less than 1 mA and occupies 28 mm/sup 2/ of silicon. The dynamic range is larger than 66 dB for the maximum input signal (54 mV/sub rms/=108 dB SPL).

[1]  Masao Hotta,et al.  Measurement of digital noise in mixed-signal integrated circuits , 1995 .

[2]  Albert C. van der Woerd,et al.  Analog circuits for a single-chip infrared controlled hearing aid , 1993 .

[3]  Qiuting Huang,et al.  A novel technique for the reduction of capacitance spread in high-Q SC circuits , 1988, 1988., IEEE International Symposium on Circuits and Systems.

[4]  Edgar Sanchez-Sinencio,et al.  Programmable switched-capacitor bump equalizer architecture , 1990 .

[5]  M. J. Callahan.  Integrated DTMF receiver , 1979 .

[6]  W.M.C. Sansen,et al.  A micropower low-noise monolithic instrumentation amplifier for medical purposes , 1987 .

[7]  Rolf Becker,et al.  "Sigfred" - A Low-Power DTMF and Signalling Frequency Detector , 1990, ESSCIRC '90: Sixteenth European Solid-State Circuits Conference.

[8]  Z. Czarnul.  Novel MOS resistive circuit for synthesis of fully integrated continuous-time filters , 1986 .

[9]  J. F. Duque-Carrillo.  Control of the common-mode component in CMOS continuous-time fully differential signal processing , 1993 .

[10]  D.F. Bowers.  A Fast Settling FET Input Monolithic Instrumentation Amplifier , 1985, ESSCIRC '85: 11th European Solid-State Circuits Conference.

[11]  J. F. Dickson,et al.  On-chip high-voltage generation in MNOS integrated circuits using an improved voltage multiplier technique , 1976 .

[12]  F. Callias,et al.  A set of four ICs in CMOS technology for a programmable hearing aid , 1989 .

[13]  Wouter A. Serdijn,et al.  A Low-Voltage Low-Power Fully-Integratable Automatic Gain Control for Hearing Instruments , 1993, ESSCIRC '93: Nineteenth European Solid-State Circuits Conference.

[14]  M. Mauthe,et al.  A Micropower CMOS Circuit for Hearing Aids , 1990, ESSCIRC '90: Sixteenth European Solid-State Circuits Conference.

[15]  P.R. Gray,et al.  MOS operational amplifier design-a tutorial overview , 1982, IEEE Journal of Solid-State Circuits.

[16]  T. R. Viswanathan,et al.  Switched-capacitor frequency control loop [digital transducer] , 1982 .

[17]  Yannis Tsividis,et al.  Errata to continuous-time MOSFET-C filters in VLSI , 1986 .

[18]  Theodore P. Adams,et al.  Hearing aid with programmable remote and method of deriving settings for configuring the hearing aid , 1994 .

[19]  José Silva-Martínez,et al.  A CMOS preamplifier for electret microphones , 1995, Proceedings of ISCAS'95 - International Symposium on Circuits and Systems.

[20]  G.F. Landsburg,et al.  A monolithic dual tone multifrequency receiver , 1979, IEEE Journal of Solid-State Circuits.

[21]  Guido Torelli,et al.  Voltage multiplier with output stabilization , 1995, 38th Midwest Symposium on Circuits and Systems. Proceedings.

[22]  M. A. Tan,et al.  The problem of on-chip automatic tuning in continuous-time integrated filters , 1989, IEEE International Symposium on Circuits and Systems,.

[23]  Guido Torelli,et al.  Fully differential basic building blocks based on fully differential difference amplifiers with unity-gain difference feedback , 1995 .

[24]  Gabor C. Temes,et al.  Offset-compensated switched-capacitor integrators , 1990, IEEE International Symposium on Circuits and Systems.

[25]  Edgar Sanchez-Sinencio,et al.  A MOSFET-C variable equalizer circuit with simple on-chip automatic tuning , 1992 .

[26]  Edgar Sanchez-Sinencio,et al.  A wireless volume control receiver for hearing aids , 1995 .

[27]  Yannis Tsividis,et al.  Continuous-time MOSFET-C filters in VLSI , 1986 .