| 摘要 |
PURPOSE: A low noise amplifier and a gain control circuit of the amplifier are provided to reduce nonlinear characteristics by controlling a gain within an allowance range. CONSTITUTION: An amplifier(101) amplifies an input signal by a gain controlled according the first or the second gain control signal and outputs the amplified signal. A controller(103) generates a selection signal in accordance with a comparison result between a size of the amplified signal and a reference voltage. A gain controller(105) outputs the first gain control signal in accordance with the size of the amplified signal or the second gain control signal in accordance with the size of the reference voltage in response to the selection signal. The first gain control signal is made of binary codes with code values varied according to the size of the amplified signal. The second gain control signal has one among binary code values of the first gain control signal.
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