A RFPA (radio frequency power amplifier) circuit (150) which includes a RFPA (101), a supply voltage source (104), means (155) for applying to the RFPA a gain control bias voltage and a feedback control loop (156) for adjusting a voltage applied to the RFPA, the feedback control loop including a sampler (107) for sampling an output of the RFPA, a RF detector (109) for detecting a level of RF power sampled by the sampler, a comparator (115) for comparing an output signal from the RF detector with a reference signal, an integrator (117) for integrating an output signal of the comparator and a voltage regulator (151) having a first input from the integrator and a second input from the supply voltage source and an output connected to the RFPA, the regulator being operable to apply to the RFPA a supply voltage adjusted in response to an input signal from the integrator.
A supply voltage controlled power amplifier that comprises a power amplifier, a closed power control feedback loop configured to generate a power control signal, and a dual voltage regulator coupled to the power control feedback loop, the dual voltage regulator comprising a first regulator stage and a second regulator stage, wherein the closed power control loop minimizes noise generated by the first regulator stage.
Either linear operating mode or saturation operating mode is set as the operating mode of a high-frequency power amplifier on the basis of an operating mode set signal. The gain of a variable gain amplifier provided in front of the high-frequency power amplifier and values of output voltage and bias current supplied from a supply voltage/bias current control circuit to the high-frequency power amplifier are switched. The gain of the variable gain amplifier in the saturation operating mode is formed so as to be higher by a predetermined value than that in the linear operating mode. Accordingly, the high-frequency power amplifier operates in the designated operating mode, so that the output transmission power range can be widened.
