| 摘要 |
There is provided an active filter, having a first high-pass filter for receiving an input signal, performing filter processing of the input signal, and outputting a first signal, a second high-pass filter, an input terminal of which is connected to an output terminal of said first high-pass filter, and which receives the first signal, performs filter processing, and outputs a second signal, a differential amplifier, one input terminal of which is connected to an output terminal of said second high-pass filter to receive the second signal, the other input terminal of which is connected to the output terminal of said first high-pass filter to receive the first signal, and which outputs a third signal obtained by multiplying a difference between the first and second signals with a gain, and an adder for receiving and adding the third signal output from said differential amplifier and the input signal, and outputting a sum signal. Since the active filter can be constituted by the first and second high-pass filters, the differential amplifier, and the adder, the number of elements is reduced. <IMAGE>
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