AMPLIFYING CIRCUIT DEVICE

摘要

PROBLEM TO BE SOLVED: To provide an amplifying circuit device capable of avoiding the occurrence of drain current exceeding the standard value by preventing the input of an unintended low-frequency signal.

SOLUTION: In a sealing member of a J-FET 1, capacitance 4 is added in series with a gate. The capacitance 4 and a resistor 2 connected between the gate and a source of the J-FET 1 constitute a high-pass filter. The setting of the cutoff frequency of the high-pass filter to less than 20 Hz can cut off frequencies lower than the lower limit of the audible frequency band without degrading an audio signal. An insulating layer is provided on the rear surface of a substrate constituting a chip. The parallel-plate-type capacitor 4 using the insulating layer as a dielectric is constituted by a conductive member and the substrate.

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