| 摘要 |
A variable gain amplifier is provided by an embodiment of the present invention. The variable gain amplifier includes a first-stage amplifier circuit composed of a first self-bias transistor load, an adjustable resistance load, a first pair of differential tubes, a first resistor and a current source, wherein all of them are connected in sequence; and the variable gain amplifier also includes a second-stage amplifier circuit composed of a second pair of differential tubes, a second self-bias transistor load, a second resistance load and a third resistance load. The variable gain amplifier adopts the structure of the two-stage amplifier circuit, so that a higher gain could be realized and a gain regulating circuit could be simplified. |
