or the like application_number US 23330708 A description referring now to fig1 the present invention provides an amplifier 10 including an npn heterojunction bipolar transistor 12 having a collector base and emitter terminal labeled c b and e respectively according to typical common base configuration the base of the transistor 12 is connected to signal ground possibly through one or more passive components the collector of the transistor 12 is connected to an output terminal 14 from which an amplified radiofrequency signal will be obtained and the emitter of the transistor 12 is connected to an input terminal 16 at which an input signal is applied an input bias circuit 18 of a type generally known in the art biases the emitter of the transistor 12 with respect to its base within the operating range of the transistor 12 in the present invention the collector of the transistor 12 is biased by an active current source 20 in distinction from a voltage source under voltage source biasing a variable current to the collector is supplied as a function of the output power at the output terminal 14 in contrast the active current source 20 delivers a substantially constant current to the collector of the transistor 12 regardless of the output power referring to fig2 the present invention can alternatively be used with.