(C-V) and y-parameters determination of JFETs under different environmental conditions

The C-V characteristics of n-channel JFET have been measured under different environmental conditions of temperature up to 140 °C and γ-rays up to 100 kGy. For low bias voltage and frequency, the input capacitance, Ciss, is shown to be a direct function of temperature. On the other hand, its value was shown to decrease from 11.68 down to 8.17 nF due to γ-exposure up to 100 kGy. The y-parameters of common source amplifier were calculated under the influence of temperature and γ-rays. The results show that the susceptance component of the admittance increases due to increase in temperature, while decreasing after γ-exposure. Considering the cutoff frequency fT0, it is clear that as the temperature increases from 30 up to 140 °C, fT0 dropped from 47 MHz down to 5 MHz, measured at 0.8 V. On the other hand its value was shown to increase from 43 MHz up to 102 MHz, measured at the same bias voltage, due to γ-exposure up to 100 kGy.