Temperature measurement of a power semiconductor switching element

A method for measuring a temperature of a semiconductor power switch having a built-in temperature-dependent gate resistor via a circuit comprising a non-inverting amplifier circuit having an operational amplifier and a feedback resistor that is disposed between a negative input and an output of the operational amplifier, wherein the built-in temperature-dependent gate resistor is disposed between the negative input of the operational amplifier and an input of the circuit, the method comprising:

• operating the circuit with an input signal having a frequency that is in a predefined frequency range such that the built-in temperature-dependent gate resistor forms a substantial part of input impedance of the semiconductor power switch;
• measuring a gain of the non-inverting amplifier circuit;
• and
• calculating a resistance of the built-in temperature-dependent gate resistor by way of the measured gain and determining the temperature of the semiconductor power switch.

A method for measuring a temperature of a semiconductor power switch having a built-in temperature-dependent gate resistor via a circuit comprising a non-inverting amplifier circuit having an operational amplifier and a feedback resistor that is disposed between a negative input and an output of the operational amplifier, wherein the built-in temperature-dependent gate resistor is disposed between the negative input of the operational amplifier and an input of the circuit, the method comprising:

• operating the circuit with an input signal having a predefined frequency that is in a predetermined frequency range such that the built-in temperature-dependent gate resistor forms an integral part of input impedance of the semiconductor power switch;
• measuring an output signal from the non-inverting amplifier circuit for at least two temperature settings;
• calculating a temperature dependence of the output signal;
• and
• determining the temperature of the semiconductor power switching element based on the output signal and the calculated temperature dependence.