A comparative study of gamma radiation effects on a logarithmic amplifier based multiplier circuit using common and Precision Devices

Abstract

Logarithmic circuits facilitate the compression of a wide range of current signals and are, therefore, highly suitable in nuclear instrumentation. Functioning of these circuits, however, can be seriously affected if the characteristic properties of operational amplifiers (Op Amps) (which make up these circuits) such as input offset voltage and input bias current get altered in the harsh nuclear environment. Reliability considerations demand that performance of such circuits be predicted under such conditions. This paper reports a comparative study of the performance of logarithmic amplifier circuits, comprising of different types of Op Amps, when exposed to gamma radiation. Study is done using a multiplier circuit where log and antilog circuits are used. A useful approach has been adopted wherein the multiplier circuit is modelled using the commonly used Op Amp model which allows simulation of the effect of gamma radiation damage using the experimentally obtained bias current and offset voltage values, without the need for dedicated software. The type of input stage of the Op Amp (FET, Bipolar etc.) significantly affects the performance of these circuits under radiated conditions. Therefore, a wide range of commonly used devices (HA17741, LM324 etc. having bipolar stages) and precision devices (OP15, OPA128JM and LMC6001AIN having JFET stages) are considered. Simulation and experimental results are included.

Key Words:

• Logarithmic circuits
• input offset voltage
• input bias current
• gamma radiation

Additional information

Notes on contributors

Vivek Agarwal

Vivek Agarwal

Vivek Agarwal received a bachelor’s degree in Physics from St. Stephen’s college, Delhi University. He then obtained an integrated Master’s degree in Electrical Engineering from Indian Institute of Science, Bangalore. Subsequently he pursued a Ph.D. degree in the dept. of Electrical and Computer Engineering, University of Victoria, Canada. After obtaining the Ph.D. degree, he briefly worked for Statpower Technologies, Burnaby, Canada as a research engineer. In 1995 he joined the department of Electrical Engineering, Indian Institute of Technology-Bombay, where he is currently a professor. His main field of interest is power electronics. He works on the modelling and simulation of new power converter configurations, intelligent control of power electronic systems, power quality issues, EMI/EMC issues and conditioning of energy from non-conventional sources. He is a senior member of IEEE, Fellow of IETE and a life member of ISTE.

V P Sundarsingh

Vp Sundarsingh

Vp Sundarsingh obtained an M.Sc. in Electronics from Madras University, India. He then obtained a Master’s degree, followed by a Ph.D. in Electrical Engineering from Indian Institute of Technology, Bombay, India. In 1967 he joined as a faculty member in the Department of Electrical Engineering, Indian Institute of Technology – Bombay. His areas of research include power electronics, power devices, power quality and solar power conditioning. He is a fellow of IETE. He superannuated from active service in 2002 but is still very active in research.

Vishwanath Ramachandran

Vishwa Ramachandran

Vishwa Ramachandran received a bachelor’s degree in Instrumentation Engineering from University of Mumbai, Mumbai, India in 1999. In 2003, he received his Master’s degree in Electrical Engineering from the Indian Institute of Technology – Bombay. He is currently working towards his M.S./Ph.D. in the Department of Electrical Engineering and Computer Science from Vanderbilt University, USA. His main field of interest is modelling of radiation effects on electronic circuits and microelectronic devices, due to both single events and total dose. He is a student member of IEEE and a member of Nuclear and Plasma Sciences Society.