Chip Temperature Measurement
Original Publication Date: 1985-Jun-01
Included in the Prior Art Database: 2005-Feb-18
Semiconductor chip temperature is measured by using a single non-calibrated diode which may be a transistor connected as a diode. Currents having a ratio of two to one are alternately switched through the diode and the resulting AC voltage measured. Theory shows that this voltage is proportional to absolute temperature and so calibration is theoretically not required. The well-known relationship between collector current and base-emitter voltage for a bipolar transistor is: Vbe = (kT/q)loge(Ic/Is) (1) provided Ic/Is >>1 where k=Boltzmann's constant (1.38 x 10-23 joules/ŒK) T=absolute temperature, ŒK q=charge of an electron (1.6 x 10-19 coulomb) Is=theoretical reverse saturation current-approx 1.