Study of the Gamma-ray Effects on Operational Amplifier Characteristics

Exposing the 'μA 741C' Operational-Amplifiers to gamma-rays with different doses up to 3.5x106 rad was shown to seriously affect their electrical characteristics. Consequently, the devices lose their main features as a result of major defects that cause deviation in the basic behaviors of the system. The differential-mode gain and input resistance values were dropped from 185 V/mV to 70 V/mV and from 9x106 ohm to 1.5x106 ohm respectively. Also, the offset voltage adjustment range was decreased from the band (-12 to +14) mV down to (-1.50 to +2.0) mV. The common-mode rejection ratio which had, as well, an initial value of 100 dB before irradiation reaches a value of 2.0 dB after exposure to 3.5x106 rad. On the other hand, the power supply rejection ratio and input offset voltage and current were shown to have a pronounced increase as a result of gamma exposure. Their values reach 430 μV/V, 75 mV and 50 nA although they have initial values of 20 μV/V, 5.0 mV and 1.0 nA respectively