Patent ID: 7679417

Claim:
An attenuator, comprising: an input port, an output port, an attenuation control port, and first and second supply voltages; a first series attenuation branch, including a first field effect transistor, connected between the input port and an intermediate node; a second series attenuation branch, including a second field effect transistor, connected between the node and the output port; a shunt attenuation branch, including a third field effect transistor, connected between the intermediate node and the first supply voltage connection, a gate of third field effect transistor receiving the attenuation control signal from the attenuation control port; and a bias control circuit, comprising a fourth field effect transistor receiving at a gate thereof the attenuation control signal from the attenuation control port, and having a first terminal connected to the first supply voltage, and a resistor connected between a second terminal of the fourth field effect transistor and the second supply voltage, wherein a voltage at the second terminal of the fourth field effect transistor is coupled to gates of the first and second field effect transistors to supply a bias voltage thereto in response to the attenuation control signal.