contents             full texthtml,   pdf   

(C-V) Y- p-n





17 2009 .

(C-V) and Y-Parameters Determination of JFETs under Different Environmental Conditions


S. M. El-Ghanam

Womens College for Arts, Science, and Education,
Ain shams University, Heliopolis, Cairo Egypt

Received July 17, 2009


The C-V characteristics of n-channel JFET have been measured as a function of temperature up to 140 0C and γ- rays up to 100 kGy. The results show that the input capacitance Ciss is an increasing function of temperature when measured at small bias voltage and low frequency bands. On the other hand, Ciss was shown to decrease from 11.68 down to 8.17 nF due to γ- exposure up to 100 kGy. In addition, the physical parameters of the gate-source junction were investigated, where their values were to shown to be funcion of both temperature increasing and γ- exposure. The values of the Y- parameters of common-source amplifier were calculated under influence of temperature and γ- rays. The result shows that, the susceptance component of the admittance increases due to temperature increasing, while decreasing after γ- exposure. The investigation was extended to include the temperature and radiation effects on the cutoff frequency fT0 . It is clear from calculations that, as the temperature increases from 30 0C up to 140 0C, fT0 dropped from 47 MHz down to 5 MHz, at 0.8 Volt. On the other hand its value was shown to increase from 43 MHz up to 102 MHz, at 0.8 Volt, due to γ- exposure up to 100 kGy.


Keywords: JFET, input capacitance, Y-parameters, quality factor, dissiption factor, phase angle, impedance, cutoff frequency.