Patent ID: 7061314

Claim:
A system for operating a power amplifier in a mobile handset, comprising: a carrier amplifier having a carrier input terminal and a carrier output terminal; a peak amplifier having a peak input terminal, a peak output terminal and a control terminal for receiving a voltage control signal, the peak amplifier configured to vary at least one characteristic of the power amplifier based upon the voltage control signal; an active phase shifter, coupled to the carrier input terminal and the peak input terminal, for generating a peak amplifier input signal delayed in phase from a carrier amplifier input signal, the active phase shifter further comprising: a lower differential unit, coupled to an input stage and the peak input terminal, for generating the peak amplifier input signal, an upper differential unit, coupled to the input stage and the carrier input terminal, for generating the carrier amplifier input signal, and a phase control unit, coupled to the input stage and the upper differential unit, for tuning a phase difference between the peak amplifier input signal and the carrier amplifier input signal within a phase tolerance; and an output matching unit, coupled to the carrier output terminal and the peak output terminal, for receiving a carrier output power signal and a peak output power signal and forming a power amplifier output power signal at a power amplifier output stage.