Patent ID: 7787565

Claim:
A Cartesian feedback system comprising: a forward path for receiving an input baseband signal having two components, and performing up-conversion to output a radio frequency (RF) signal; a power amplifier for amplifying the RF signal output from the forward path; and a feedback path for down-converting at least a sample of the output from the power amplifier to produce a feedback baseband signal comprising two components, and providing the feedback baseband signal to the forward path in order to be summed with the input baseband signal at a summing junction; and wherein the forward path includes a baseband phase shifter followed by one or more loop filters for adjusting the phase of a baseband signal output from the summing junction in order to compensate for any phase shifts induced in the system, the forward path including a quadrature up-converter driven by a local oscillator and phase splitter, and the feedback path including a quadrature down-converter driven by the same local oscillator and phase splitter as the quadrature up-converter.