Turbocharger rotation detector

A turbocharger rotation detector for detecting a rotational speed of a compressor wheel of a turbocharger, wherein the turbocharger comprises a turbine mounted on an exhaust gas path of a vehicle internal combustion engine and comprised of a turbine wheel rotationally driven by the exhaust gas from the internal combustion engine, and a compressor mounted on an air intake path of the internal combustion engine and comprised of the compressor wheel rotationally driven by rotation of the turbine wheel, the turbocharger rotation detector comprising:

• an oscillator circuit that comprises a coil generating a magnetic field inducing an eddy current in blades of the compressor wheel and outputs an AC signal as a detection signal, the AC signal having an amplitude varying with approach and recession of the blades;
• a first detector circuit comprising a first integrator circuit for integrating, of the detection signal, a signal component that is of a positive voltage higher than a reference potential;
• a second detector circuit comprising a second integrator circuit for integrating, of the detection signal, a signal component that is of a negative voltage lower than the reference potential;
• a first interrupter circuit that passes, of an output signal of the first detector circuit, an AC component that varies in voltage with approach and recession of the blades and that interrupts a DC component;
• a second interrupter circuit that passes, of an output signal of the second detector circuit, an AC component that varies in voltage with approach and recession of the blades and that interrupts a DC component;
• and
• a differential amplifier circuit to which the signals passing through the first and second interrupter circuits are input.