A differential impedance to frequency converter for generating a signal having a frequency independent of temperature variations and proportional to impedance variations of a sensor exposed to a physical quantity. The differential impedance to frequency converter comprises a first impedance to frequency converter configured to generate a signal having an output frequency proportional to the impedance variations of the sensor exposed to the physical quantity; a second impedance to frequency converter configured to generate a signal having a reference frequency proportional to the impedance variations of a reference sensor identical to said sensor but unexposed to the physical quantity, the second impedance to frequency converter having a construction similar to the first impedance to frequency converter; and a D flip-flop having a data input terminal, a clock input terminal and an output terminal, the data input terminal receiving the reference frequency from the second impedance to frequency converter, the clock input receiving the output frequency from the first impedance to frequency converter, and the output terminal generating a difference of the reference frequency and the output frequency.