Characterization and Operation of Some Operational Amplifiers at Different Environmental Conditions
S. M. El-Ghanam, F. A. S. Soliman, and H. A. Ashry
This paper introduces the effect of temperature and γ-radiation on four types of operational amplifiers (HA17741 OK, HA17741 1D1, LM741 CN and μA741 CN). The op-amp parameters (input offset voltage, input bias current, offset current, common mode rejection ratio, input impedance, output impedance, closed loop gain, and slew rate) were measured at different elevated temperature levels, in the range from 17 up to 75ºC. Where they all were shown to be temperature dependent with different degrees, depending on the op-amp type. For example; the input offset voltage temperature sensitivity for the op-amps HA17741 1D1 and μA741 CN were 0.454 and 13.008 respectively. On the other hand, characterization of the samples was carried out before and after γ-irradiation with total dose levels up to 200 kGy. For the types LM741 CN and μA741 CN and HA 17741 IDI, the input offset voltage values increased from initial values of –2.12, 2.56 and 1.4 mV up to 2.21, 4.42 and 4.82 mV, respectively, due to gamma expose up to 50 kGy. Finally, it is clearly shown that the radiation dependence of the op-amp electrical parameters is a function of the fabrication technique of the op-amps.
Keywords: Operational amplifiers, γ-irradiation, input offset voltage, common mode rejection ratio, input and output impedance, closed loop gain, and slew rate.