Patent ID: 8576006

Claim:
A variable gain amplifier, comprising: a first input transistor having a base for receiving a first radio frequency (RF) input signal; a second input transistor having a base for receiving a differential RF signal; a first plurality of differential transistor pairs, said first plurality of differential transistor pairs connected in parallel to a first biasing transistor, the first biasing transistor configured to receive a bias voltage at its gate to keep the first biasing transistor in a conducting state; a second plurality of differential transistor pairs, said second plurality of differential transistor pairs connected in parallel to a second biasing transistor, the second biasing transistor configured to receive a bias voltage at its gate to keep the second biasing transistor in a conducting state; a first output transistor having its gate connected to the drain of one transistor in each differential transistor pair of the first plurality of differential transistor pairs and the drain of the first biasing transistor, and the first output transistor having its drain connected to an output terminal for delivering an output based on the first RF signal; and a second output transistor having its gate connected to the drain of one transistor in each differential transistor pair of the second plurality of differential transistor pairs and the drain of the second biasing transistor, and the second output transistor having its drain connected to an output terminal for delivering an output based on the differential RF signal; wherein the first and second pluralities of differential transistor pairs are configured in a cascade configuration as a single device having individually controllable fingers to provide a wideband gain control of the variable gain amplifier.