TEMPERATURE SENSING CIRCUITS

A temperature sensing circuit suitable for integration with a power semiconductor device (MOSFET/IGBT) includes temperature-sensing p-n diode means (D1, D2, etc . . . ) integrated together with first and second IGFETs (M1 and M2). A current path through the temperature-sensing p-n diode means (D1, D2, etc . . . ) provides a voltage drop (Vf) having a negative temperature coefficient. The IGFETs (M1 and M2) are coupled in separate current paths from each other so as to have separate gate-to-source voltage signals (Vgs1 and Vgs2) between their source and gate electrodes (s and g). The gate-to-source voltage (Vgs1) of the first IGFET (M1) has a negative temperature coefficient of greater magnitude than the temperature coefficient (if any) of the gate-to-source voltage (Vgs2) of the second IGFET (M2). One of the source and gate electrodes (s or g) of the first IGFET (M1) is coupled to the p-n diode means (D1, D2, etc . . . ), and the first and second IGFETs (M1 and M2) are coupled together as or with a comparator (COMP) to compare the voltage drop (Vf) from the p-n diode means (D1, D2, etc . . . ) with any difference between the gate-to-source voltages (Vgs1 and Vgs2) of the IGFETs (M1 and M2) and so provide a logic output signal (Tabs) indicative of a sensed temperature in relation to a temperature threshold. The IGFETs (M1 and M2) are of the same insulated gate field effect type as each other, typically an N-channel enhancement type, so that the second IGFET (M2) has a gate threshold value (VT) which balances that of the first IGFET (M1) and provides the comparator (COMP) with a precision reference level corresponding to the temperature threshold and less susceptible to variation in process parameters associated with the IGFET threshold voltages.