Threshold voltage variations with temperature in MOS transistors

Variations with temperature in the threshold voltage of n- and p-channel MOS transistors are obtained by calculation as well as measurement, with the results comparing quite closely. The amount of voltage change per °C under normal operating conditions is found to be dependent upon the channel doping concentration. The calculations show that for either n- or p-channel devices the voltage change per °C is -4 mV/°C for an impurity concentration of 3 × 10¹⁶/cm³and -2 mV/°C for an impurity concentration of 10¹⁵/cm³. This information is important because if the MOS transistor is subjected to a changing temperature environment, the accompanying threshold voltage change may be intolerable.