A system comprising: a multi-stage RF amplifier (120; 220; 420); a single active bias circuit (110; 210;410) arranged to actively bias the multi-stage RF amplifier to at least partially compensate for amplifier manufacture processing variations and/or bias circuitry temperature changes and to control a bias to each of a plurality of amplification stages of said multi-stage RF amplifier substantially independently of the amplifier manufacture processing variations and/or the bias circuitry temperature changes, the single active bias circuit (110; 210; 410) having a single bias output (151; 251; 451) configured to provide the bias to each of the plurality of amplification stages of said multi-stage RF amplifier and wherein the single active bias circuit is electrically connected to each of said plurality of amplification stages; and a differential device configured to receive said single bias output and cause the bias provided to one of said plurality of amplification stages to be different from the bias provided to another of said plurality of amplification stages, wherein each of said plurality of amplification stages comprises a transistor device, and wherein two terminals of each transistor device are electrically connected to said single active bias circuit thus forming a bias loop for each of said plurality of amplification stages; the system further comprising a stabilization resistor (140; 440) connected to the single bias output (151; 251; 451) at one end and to either a gate or a base of each transistor device at another end, wherein each bias loop includes said stabilization resistor (140; 440). a multi-stage RF amplifier (120; 220; 420); a single active bias circuit (110; 210;410) arranged to actively bias the multi-stage RF amplifier to at least partially compensate for amplifier manufacture processing variations and/or bias circuitry temperature changes and to control a bias to each of a plurality of amplification stages of said multi-stage RF amplifier substantially independently of the amplifier manufacture processing variations and/or the bias circuitry temperature changes, the single active bias circuit (110; 210; 410) having a single bias output (151; 251; 451) configured to provide the bias to each of the plurality of amplification stages of said multi-stage RF amplifier and wherein the single active bias circuit is electrically connected to each of said plurality of amplification stages; and a differential device configured to receive said single bias output and cause the bias provided to one of said plurality of amplification stages to be different from the bias provided to another of said plurality of amplification stages, wherein each of said plurality of amplification stages comprises a transistor device, and wherein two terminals of each transistor device are electrically connected to said single active bias circuit thus forming a bias loop for each of said plurality of amplification stages; the system further comprising a stabilization resistor (140; 440) connected to the single bias output (151; 251; 451) at one end and to either a gate or a base of each transistor device at another end, wherein each bias loop includes said stabilization resistor (140; 440).