High-frequency amplifier of a radio transmitter

A radio transmitter including antenna means for transmitting a radio signal and amplifier means coupled to receive an input signal from a voltage oscillator means for generating an output to said antenna means, said amplifier means comprising:

• an amplifier stage having a two-gate field-effect transistor, a first gate of said two-gate transistor being coupled to said input signal, wherein the operating point of the two-gate transistor is set by appropriately biasing said first gate;
• and
• control feedback means coupled to a second gate of said two-gate transistor from any subsequent amplifier stage, said control feedback means comprising comparator means having a first input for receiving a feedback signal proportional to the actual transmission power, a second input for receiving a set value signal corresponding to a desired transmission power;
• and
• an output for applying a control signal which is a function of the difference between the signals received at said first and second inputs of said comparator means to the second gate of said two-gate transistor for controlling a gate of said transistor.