| 摘要 |
PROBLEM TO BE SOLVED: To provide an infrared detecting device capable of facilitating frequency adjustment of a band-pass filter characteristic of a voltage amplification circuit, capable of executing high-gain voltage amplification without generating output saturation, and capable of being integrated. SOLUTION: This infrared detecting device having a pyroelectric element 1, an I/V conversion circuit 2 for converting a current signal outputted from the pyroelectric element 1 into a voltage signal, and a voltage amplification circuit 3 for amplifying the voltage signal outputted from the I/V conversion circuit 2 with a prescribed frequency band, and for outputting a detection signal, has such a characteristic that the voltage amplification circuit 3 is composed by connection of a plurality of steps of primary filters and composed of a switched capacitor filter in which a resistance of the primary filter is used as a switched capacitor.
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