Patent ID: 9143108
Filing Date: 2015-09-22
Classification: H03G

Abstract:
1. A variable gain amplifier comprising: a first input terminal, a second input terminal and an output terminal; an operational amplifier having a non-inverted input terminal connected to the second input terminal and an output connected to the output terminal; a first resistor interposed between the first input terminal and an inverted input terminal of the operational amplifier; second and third resistors interposed in series between the inverted input terminal of the operational amplifier and the output terminal; and a fourth variable resistor having a first terminal connected to a node between the second resistor and the third resistor and a second terminal connected to the non-inverted input terminal of the operational amplifier, wherein the fourth variable resistor includes a plurality of resistance passes interposed in parallel between the first terminal and the second terminal, each of the resistance passes including a resistor and a switch connected in series.