To keep outputs almost constant even if temperature chances.
Magnetoresistive elements 4, 5 detect changes in magnetic field caused by a gear 2 rotating in conjunction with a shaft 1. An amplification circuit 6 has a gain-determining input resistance 8 placed at the input terminal of an operational amplifier 7 and a gain-determining feedback resistance 9 placed on a feedback course from the output terminal to the input terminal of the operational amplifier 7, and signals outputted from the magnetoresistive elements 4, 5 having temperature characteristics are inputted to the amplification circuit 6, which in turn amplifies the signals for output. The gain-determining input resistance 8 and the gain-determining feedback resistance 9 are constructed of a P well region and a P+ region and have temperature characteristics, and the temperature characteristics of gains specified by the gain-determining input resistance 8 and the gain-determining feedback resistance 9 cancel out the temperature characteristics of the magnetoresistive elements 4, 5.
MAKINO YASUAKI
SHINODA TAKESHI
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