To provide a charge detection circuit that allows an easy adjustment of an input gain of a differential amplifier.
In a differential charge detection circuit, one end of physical quantity detection sensors 1A and 1B composed of either a charge generation type sensor or capacitance change type sensor is connected to a negative input terminal of a differential amplifier 3, the other end is connected to a positive input terminal of the differential amplifier 3, a feedback resistor Rf and a feedback capacitor Cf are connected in parallel between an output terminal and the negative input terminal of the differential amplifier 3, and a cancel resistor Rc and a cancel capacitor Cc are connected in parallel between the positive input terminal and a reference voltage of the differential amplifier. Variable capacitance diodes D1 and D2 to which a reverse bias potential is applied by reverse bias power supplies 7 and 9 are connected to at least one of the negative input terminal and positive input terminal of the differential amplifier, allowing the differential charge detection circuit to adjust a gain.
| JPS5545230 | VARIABLE GAIN AMPLIFIER CIRCUIT |
MATSUO NAOYUKI
KISHIRO MASAMI
Hide Tanaka Tetsu
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