Method for estimating the temperature in an internal combustion engine

A circuit for estimating a temperature in an internal combustion engine, the circuit comprising:

• a sensor resistor (RTD) having a predetermined resistance-temperature characteristic;
• a computer (M) connected in parallel to the sensor resistor (RTD) and arranged to:
• measure a sensor voltage (VRTD) across said sensor resistor (RTD);
• calculate a resistance value of said sensor resistor (RTD) based on said sensor voltage (VRTD);
• and
• estimate a temperature value using said resistance value and the predetermined resistance-temperature characteristic of the sensor resistor (RTD);
• a first branch of a current mirror arrangement connected in series to said sensor resistor (RTD);
• a reference resistor (R0) connected in series to a second branch of the current mirror arrangement,
• wherein the computer (M) is connected in parallel to the reference resistor (R0) and being arranged to:
• measure a reference voltage (V0) across said reference resistor (R0);
• and
• calculate the resistance value of said sensor resistor (RTD) based on said sensor voltage (VRTD) and said reference voltage (V0);
• and
• an analogue to digital converter (ADC) in parallel to the sensor resistor (RTD) and the reference resistor (R0) configured to provide digital values representative of the sensor voltage (VRTD) and the reference voltage (V0).