Anomalous noise behavior of the junction-gate field-effect transistor at low temperatures

Measurements are reported on the noise resistance and the noise conductance of the junction-gate FET in the temperature range 77°K-400°K. At low temperatures anomalous noise behavior has been observed. The measurements are discussed in the light of existing theories and, when necessary, the theoretical model has been extended. The agreement is satisfactory. Generally the extra noise is caused by mobility saturation, increased free-carrier temperature, free-carrier trapping and multiplication effects in the pinched-off region. Finally, several applications are discussed in relation to the limiting noise sources.