Patent ID: 7570932

Claim:
A radio frequency (RF) system capable of operating in one of a first mode and a second mode comprising: quadrature power amplifier circuitry adapted to: when operating in the first mode, provide a first amplifier signal; when operating in the second mode, provide the first amplifier signal and a second amplifier signal; and select one of the first mode and the second mode based on a power control signal; a quadrature power divider and combiner circuit adapted to: when operating in the first mode, receive, divide, and phase-shift the first amplifier signal into two first mode output signals of approximately equal amplitude, which are phase-shifted approximately 90 degrees from each other; and when operating in the second mode, receive, phase-shift, and combine the first amplifier signal and the second amplifier signal into a second mode output signal; an impedance shifting circuit coupled to the quadrature power divider and combiner circuit, which when operating in the first mode is adapted to present an impedance to the quadrature power divider and combiner circuit that causes one of the two first mode output signals to be substantially reflected, phase-shifted, and combined with the other of the two first mode output signals to create a combined first mode output signal; and control circuitry adapted to provide the power control signal.