A comparative study of gamma radiation effects on ultra-low input bias current linear circuits under biased conditions

Abstract

Abstract-Ultra-low input bias current linear circuits are used in several applications requiring them to work under varying conditions of temperature, humidity, radiation etc. which influence their performance. This paper presents a first time study of gamma radiation effects on ultra low input bias current linear circuits under biased conditions for small signal dc applications. Under biased conditions, radiation-induced photo currents play a significant role. A noncatastrophic radiation leakage environment has been considered. The linear circuits selected are of different makes and have different input stages, such as those based on JFET and MOS structures. Variations of dc characteristic parameters, such as input offset voltage and input bias current have been studied. Extensive experimental results are presented, including the effects of annealing, on critical parameters. It is seen that these devices behave differently on exposure to gamma radiation, depending on the structure of their input stage. The MOSFET-based stages show a greater change in input offset voltage, whereas FET-based input stages exhibit a greater change in input bias currents. Chopper stabilised linear circuits exhibit lesser deviation in their offset voltages and bias currents due to an inherent chopping action at their input stage that automatically compensates for any variations in these parameters.

Taguchi Based Performance and Reliability Improvement of an Ion Chamber Amplifier for Enhanced Nuclear Reactor Safety

“…It has been observed that the input bias current, input offset voltage, and input offset current of very low input bias current op-amps change significantly on exposure to gamma radiation. The input bias current of op-amps DN8500A, OPA111AM and INA101AM varies drastically [5], [9] with exposure to gamma radiation. The input bias current of the op-amp DN8500A increases from 0.023 pA to 0.145 pA after exposing to 5 krads.…”

“…However, as mentioned earlier, the ion chamber bin is located adjacent to the reactor core for sensing neutron flux responsible for producing reactor power. A small fraction of the gamma radiation is able to leak out and may affect the semiconductor devices of the neighboring electronic systems, which are sensitive to gamma radiation exposure [6]- [9]. For example, it is well known that the basic parameters of an op-amp, e.g., the input bias current, the input offset voltage and the input offset current, change in the nuclear radiation environment [10].…”

“…Since the currents during the reactor start-up (not source range start-up, but normal power range start-up after typically a few days of shut-down) are in the range of pA to A, it is imperative that the resistance of the input stage of the DC amplifier (log amplifier) is of the order of and its bias current is of the order of 0.01 pA. This high input impedance necessitates mounting of these ICs on Teflon "stand-offs" [9], since the glass-epoxy Printed Circuit Board (PCB) has an impedance of the order of only . Further, the amplifier is housed in a hermitically sealed container in order to prevent moisture condensation on its input leads, which could result in a low impedance path parallel to the input impedance stage.…”

Minimum dropout voltage on a serial pnp transistor of a moderately loaded voltage regulator in a gamma radiation field

“…The re sponse of volt age reg u la tors in the ra di ation en vi ron ment has been in ten sively ex am ined in previ ous years, pri mar ily due to their ad van tages over switch ing reg u la tors: a sim ple elec tric cir cuit, low price, re duced noise and rapid tran sient re sponse to load con di tions [1]. Con cern over the ex am i na tion of voltage reg u la tors par tic u larly arose af ter the dis cov ery of the en hanced low dose rate sen si tiv ity (ELDRS) ef fect, lead ing to the anal y sis of nu mer ous pro ce dures an tic ipated for the pro cure ment of pre cise in for ma tion on the ra di a tion tol er ance of sam ples de signed for ser vice on sat el lites in the space ra di a tion en vi ron ment [1][2][3][4][5][6][7][8][9][10][11][12][13][14].…”