Patent ID: 7511573

Claim:
In an amplification circuit using amplifying devices in an audio system, an input and output signal preservation circuit of an amplification circuit, comprising: an input signal preservation unit that is connected with an input terminal of an amplification device of an amplification circuit capable of amplifying an AC input signal using a certain amplification device and outputting the same and increases an input resistance value with respect to the input signal and prevents an attenuation of the input signal; and an output signal preservation unit that is connected with an output terminal of the amplification device and increases an output resistance value with respect to the amplification signal and prevents an attenuation of the amplification output signal for thereby compensating a voltage variation ratio with respect to the amplification output signal. wherein said input signal preservation unit includes; a bias resistor connected in parallel with an input terminal of the amplification device; and a reactor that is connected in series with the bias resistor and operates as an AC resistor and increases an input resistance value together with the bias resistor for thereby preventing a leakage of the AC input signal.