A 230-nW 10-s time constant CMOS integrator for an adaptive nerve signal amplifier

This paper describes a micropower CMOS integrator with an extremely large time constant for use in a variety of low-frequency signal processing applications. The specific use of the integrator in an implantable biomedical integrated circuit is described. The integrator is based on the OTA-C approach and a very small transconductance of 100 pA/V was achieved by cascading a short chain of transconductance-transimpedance stages. The time constant of the integrator is tunable between about 0.2 and 10 s, and any offset voltages at the output terminal can be trimmed out. The circuit was fabricated in a 0.8-/spl mu/m CMOS process, dissipates 230 nW from /spl plusmn/1.5 V power supplies (excluding the bias circuitry and output buffers) and has a core area of 0.1 mm/sup 2/. The integrator offers superior performance in terms of power consumption, die area and time constant when compared to previously published work.

[1]  Mohammed Ismail,et al.  Micropower CMOS GM-C filters for speech signal processing , 1997, Proceedings of 1997 IEEE International Symposium on Circuits and Systems. Circuits and Systems in the Information Age ISCAS '97.

[2]  Jorge Salcedo-Suñer,et al.  IC Voltage to Current Transducers with Very Small Transconductance , 1997 .

[3]  Robert Rieger,et al.  Design of an adaptive interference reduction system for nerve-cuff electrode recording , 2004, IEEE Transactions on Circuits and Systems I: Regular Papers.

[4]  P. Garde.  Transconductance cancellation for operational amplifiers , 1977, IEEE Journal of Solid-State Circuits.

[5]  Yannis Tsividis,et al.  Integrated continuous-time filter design - an overview , 1994, IEEE J. Solid State Circuits.

[6]  Iasonas F. Triantis,et al.  Comparison of three ENG tripolar cuff recording configurations , 2003, First International IEEE EMBS Conference on Neural Engineering, 2003. Conference Proceedings..

[7]  Yannis Tsividis,et al.  Integrated continuous-time filter design , 1993, Proceedings of IEEE Custom Integrated Circuits Conference - CICC '93.

[8]  Franco Maloberti,et al.  A 60-dB dynamic-range CMOS sixth-order 2.4-Hz low-pass filter for medical applications , 2000 .

[9]  Peter R. Kinget,et al.  Full integration of extremely large time constants in CMOS , 1991 .

[10]  W.M.C. Sansen,et al.  An area-efficient approach to the design of very-large time constants in switched-capacitor integrators , 1984, IEEE Journal of Solid-State Circuits.

[11]  A. Demosthenous,et al.  Design of a low-noise preamplifier for nerve cuff electrode recording , 2003, IEEE J. Solid State Circuits.

[12]  L.J. Stotts.  Introduction to implantable biomedical IC design , 1989, IEEE Circuits and Devices Magazine.

[13]  M. Haugland,et al.  Natural neural sensing and artificial muscle control in man , 2004, Experimental Brain Research.

[14]  U. Yodprasit,et al.  Micropower transconductor for very-low frequency filters , 1998, IEEE. APCCAS 1998. 1998 IEEE Asia-Pacific Conference on Circuits and Systems. Microelectronics and Integrating Systems. Proceedings (Cat. No.98EX242).

[15]  T. Sinkjaer,et al.  Cuff electrodes for long-term recording of natural sensory information , 1999, IEEE Engineering in Medicine and Biology Magazine.

[16]  Kenneth R. Laker,et al.  Design of analog integrated circuits and systems , 1994 .

[17]  Iasonas F. Triantis,et al.  Experimental assessment of imbalance conditions in a tripolar cuff for ENG recordings , 2003, First International IEEE EMBS Conference on Neural Engineering, 2003. Conference Proceedings..

[18]  Edgar Sanchez-Sinencio,et al.  Transconductance amplifier structures with very small transconductances: a comparative design approach , 2002 .