Abstract: A control circuit employed in a programmable gain amplifier disclosed herein, the control circuit in one preferred embodiment of the present invention includes the following devices. The reference voltage generating circuits is to provide a voltage level for the first current generating device, and then the first current generating device produces a first current. The current repeating device generates a first repeating current with the same magnitude as the first current. In addition, the current repeating device is the current mirror of the current sources in the programmable gain amplifier to generate the second repeating current, the third repeating current and so forth. The magnitude of the second repeating current (and the subsequent bias current) is in proportional to that of the first repeating current as well as to that of the first current. An adjustable resistor, which is the emitter resistor of the first current generating device, can be varied to control the first current.