| 摘要 |
PROBLEM TO BE SOLVED: To miniaturize a sensor module offset cancel circuit. SOLUTION: The sensor module offset cancel circuit comprises a strain sensor, operational amplifiers (27-29), a controller for controlling an AD/DA converter, an RFIC connected to the controller, and an antenna connected to the RFIC where the strain sensor is formed of a bridge circuit. Voltage VIN- is outputted from a first terminal (b), voltage VIN+ is outputted from a second terminal (d), the voltage VIN- is sent to the noninverting input terminal of the amplifier 27 via a first input resistor, the voltage VIN+ is delivered to the + terminal of the amplifier 28 via a second input resistor, an output terminal of the amplifier 27 is connected to the inverting input terminal of the amplifier 29, the output terminal of the amplifier 28 is connected to the + terminal of the amplifier 29, output of the amplifier 29 is sent to an AD converter, a gain regulation signal is sent from a CPU to the power supply terminal of the amplifier 29, and a third input resistor is connected between the + terminal of the amplifier 28 and a DA converter, which sends an analog output voltage via the third input resistor. COPYRIGHT: (C)2007,JPO&INPIT
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