Patent ID: 8265894

Claim:
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 (V RTD ) across said sensor resistor (RTD); calculate a resistance value of said sensor resistor (RTD) based on said sensor voltage (V RTD ); 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 (R 0 ) connected in series to a second branch of the current mirror arrangement, wherein the computer (M) is connected in parallel to the reference resistor (R 0 ) and being arranged to: measure a reference voltage (V 0 ) across said reference resistor (R 0 ); and calculate the resistance value of said sensor resistor (RTD) based on said sensor voltage (V RTD ) and said reference voltage (V 0 ); and an analogue to digital converter (ADC) in parallel to the sensor resistor (RTD) and the reference resistor (R 0 ) configured to provide digital values representative of the sensor voltage (V RTD ) and the reference voltage (V 0 ).