| 摘要 |
A variable gain amplifier circuit with a small-sized configuration can accurately adjust the gain without causing a transmission loss of an input signal. A plurality of amplification portions are connected with each other between an amplification coupling line and a grounding line in parallel. The amplification portion includes a switching device and an amplification transistor, which induces a current corresponding to an input signal to flow between the amplification coupling line and the grounding line via the switching device when the switching device is in the on state. The amplitude gain is varied by, according to a gain control signal, separately switching on and off the switching devices of the respective amplification portions. |
