| 摘要 |
A variable gain amplifier, VGA, and related method are provided. A reference current variably controlled by a control signal is provided, then the reference current is divided to a load current and an input-control current according to differential driving between a constant reference signal and the control signal. Then the input-control current and the load current are used to respectively bias an input stage and an active load of the VGA, such that a gain of the VGA is controlled by a ratio between the input-control current and the load current. In this way, the gain can be controlled by the control signal. The VGA can provide wider gain range and better variable gain characteristics because a sum and a difference of the input-control current and the load current are both controlled by the control signal.
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