Patent ID: 7224010
Filing Date: 2007-05-29
Classification: H03F,H03G

Abstract:
1. A voltage-controlled amplifier for a signal processing system, comprising: an input voltage reception end for receiving an input voltage; a first voltage-to-current converter coupled to the input voltage reception end, for outputting a first current according to the input voltage received by the input voltage reception end; a reference current generator for generating a second current; a gain adjustment circuit coupled to the first voltage-to-current converter and the reference current generator, for receiving the first current and the second current, and adjusting a gain of the voltage-controlled amplifier, the gain adjustment circuit comprising: a first current mirror coupled to the first voltage-to-current converter, the gain adjustment circuit, and the reference current generator, comprising: an output circuit coupled to the gain adjustment circuit, for determining a difference value between a current of the collector of the first bipolar junction transistor and a current of the collector of the fourth bipolar junction transistor, for outputting an output voltage; wherein the output voltage outputted from the output circuit is controlled according to the control voltage outputted from the gain adjustment circuit.