Patent ID: 8841969

Claim:
An automatic gain control feedback amplifier, comprising: an amplification circuit unit configured to amplify voltage input from an input terminal and output the amplified voltage to an output terminal; a feedback circuit unit connected between the input terminal and the output terminal and including a feedback resistor unit of which a total resistance value is determined by one or more control signals and a feedback transistor connected to the feedback resistor unit in parallel; and a bias circuit unit configured to supply predetermined bias voltage to the feedback transistors; wherein the amplification circuit unit includes a first transistor of which a base is connected to the input terminal and an emitter is grounded, a first resistor of which one end is connected to a collector of the first transistor and the other end is connected to a power supply, a second transistor of which a base is connected to the collector of the first transistor, a collector is connected to the power supply, an emitter is connected to the output terminal, and a second resistor of which one end is connected to the output terminal and the other end is grounded.