Sensor fault detection circuit, relative angle detection device, and motor-driven power steering apparatus

A relative rotation angle detection device comprising:

• a first output unit that outputs a signal which corresponds to a relative rotation angle between two rotation shafts which are coaxially disposed;
• a first amplifier circuit that comprises a first pair of elements operating reversely to each other, and amplifies the output signal from the first output unit to output a first signal;
• a second output unit that outputs a signal which corresponds to the relative rotation angle and which has a characteristic being contradictory to a characteristic of the signal output from the first output unit;
• a second amplifier circuit that comprises a second pair of elements operating reversely to each other, and amplifies the output signal from the second output unit to output a second signal;
• and
• an abnormality detection unit that detects abnormality of the first signal or the second signal based on the first signal output from the first amplifier circuit and the second signal output from the second amplifier circuit,
• wherein characteristics of the first pair of elements of the first amplifier circuit are asymmetrical to each other, and characteristics of the second pair of elements of the second amplifier circuit are asymmetrical to each other in a same relationship with a relationship of the asymmetry between the characteristics of the first pair of elements.

A motor-driven power steering apparatus comprising:

• a first output unit that outputs a signal which corresponds to a relative rotation angle between two rotation shafts which are coaxially disposed;
• a first amplifier circuit that comprises a first pair of elements operating reversely to each other, and amplifies the output signal from the first output unit to output a first signal;
• a second output unit that outputs a signal which corresponds to the relative rotation angle and which has a characteristic being contradictory to a characteristic of the signal output from the first output unit;
• a second amplifier circuit that comprises a second pair of elements operating reversely to each other, and amplifies the output signal from the second output unit to output a second signal;
• and
• an abnormality detection unit that detects abnormality of the first signal or the second signal based on the first signal output from the first amplifier circuit and the second signal output from the second amplifier circuit,
• wherein characteristics of the first pair of elements of the first amplifier circuit are asymmetrical to each other, and characteristics of the second pair of elements of the second amplifier circuit are asymmetrical to each other in a same relationship with a relationship of the asymmetry between the characteristics of the first pair of elements.