Low Noise Junction Field Effect Transistors Exposed to Intense Ionizing Radiation

The low noise junction field effect transistor (JFET) is an essential active component in the input stages of low noise amplifiers. The changes in the characteristics of low noise JFETs have been studied after exposure to high doses of intense ionizing radiation as may be experienced in nuclear and space applications. The experimental results show that the source-drain current, transconductance and threshold voltage are only slightly degraded and that the gate junction leakage current and the noise voltage generated by the JFET both increase considerably, the latter especially at low frequencies. It is concluded from the results that JFETs should perform in low noise amplifiers provided the radiation dose does not exceed 10 Krad (Si), and that JFETs should be useable as active devices to very high doses if allowance is made for the degraded gate junction properties in specially designed circuits.