A Novel Design Criterion of A Bio-Instrumentation Solid-State Pre-Amplifier

Abstract

The impedance matrix of the n-channel FET as an active network device as well as the general matrix equation of performance of an FET cascode (ECG) bio-instrumentation pre-amplifier have been obtained. Further, an interesting design criterion for minimization of interfering noise voltage in the output of the said pre-amplifier circuit has been derived in the text. According to this criterion, the bias point of the pre-amplifier circuit is uniquely related to the active device parameters of a matched pair of FETs. The input to the said pre-amplifier may contain bio-signal source voltage along with the electrode artifacts and electrostatic and electromagnetic interfering voltages from the neighbouring electrical power networks. If the design criterion is fulfilled, there is automatic suppression of the said interfering voltages in the output of the pre-amplifier. The advantage of the present method of eliminating the interfering voltages in the recorded (ECG) bio-signal as compared to the usual frequency domain filtering techniques have been pointed out in the text.

Indexing Terms:

• Bio-instrumentation
• Pre-amplifier
• FET
• Noise

Additional information

Notes on contributors

T.K. Mitra

Dr. T.K. Mitra passed MTech in Applied Physics from University of Calcutta in 1966. He has worked on Transmission and Distribution of Electrical Power in the Calcutta Electric Supply Corporation and later in the Eastern Railway as I.R.S.E. Signal and Telecommunication Engineering Wing. He is at present working as Reader in Instrumentation group, Department of Applied Physics, University of Calcutta. His current fields of research interest include Bio-electric network modelling, circuit theory, microprocessor-based instrumentation, railway traction and signal engineering problems.

S.C. Bera

Shri Satish Chandra Bera was born in West Bengal. He received BTech and MTech degrees in Applied Physics from Calcutta University. Engaged in research work in the department of Applied Physics, C.U. since 1980. Now he is working as an Asstt. Engineer in HFC at Haldia. His research fields of interest include bio-medical instrumentation, bio-electronics etc.

P.C. Dhara

Shri Prakash Chandra Dhara was born in West Bengal in 1956. He received M.Sc. degree in Physiology (Ergonomics special) in 1978 from the Calcutta University. Now, he is working 1 as a research fellow in the department of Applied Physics, C.U. His research fields of interest include biomedical instrumentation, bio-electronics etc.