Abstract: A novel closed loop FET biasing circuit featuring a standard logic control format for operational mode switching between operating states of an FET power amplifier. In a preferred embodiment, an FET gate bias control device is provided for configuring a gate bias circuit in an FET power amplifier to accommodate a broad range of output power levels, wherein the configuration is responsive to a command which establishes an FET bias condition. The gate bias control device of the present invention comprises a circuit having a controllable switching unit which connects a plurality of resistors in the source-drain voltage circuit portion individually or in parallel to provide a multiple of resistance values each corresponding to one of four amplifier operating modes.