Patent ID: 6137365
Filing Date: 2000-10-24
Classification: H03G,H03H

Abstract:
A variable-gain amplifier circuit comprising:an operational amplifier having a gain and containing an inverting input terminal and an output terminal;a first set of resistors fabricated on a semiconductor substrate, said resistors being connected in series, said first set of resistors having a first end connected with the output terminal of said operational amplifier and a second end forming a signal-input terminal of said variable-gain amplifier circuit, said resistors of said first set being connected to each other at junctions, all or some of said junctions forming first connectable junctions capable of being connected with said inverting input terminal of said operational amplifier;a second set of resistors fabricated on said semiconductor substrate, each of said resistors of said second set having a first end connected with said signal-input terminal and a second end connected with a respective one of said junctions of said resistors of said first set; anda control means for controlling connection of said first connectable junctions with said inverting input terminal of said operational amplifier to control the gain of the operational amplifier.