Patent ID: 8059777

Claim:
A method of generating phase shifted local oscillator signals for a Cartesian feedback loop in a transmitter, comprising: receiving a local oscillator (LO) signal and a phase control signal by a LO processing unit, the LO processing unit comprising a programmable divider and at least one delay locked loop (DLL), the LO processing unit adjusting a loop phase in a time domain for the Cartesian feedback loop in the transmitter by: generating a first phase shifted LO signal and a second phase shifted LO signal from the LO signal, the second phase shifted LO signal substantially in phase quadrature to the first phase shifted LO signal, and applying the first phase shifted LO signal and the second phase shifted LO signal to a modulator; generating a third phase shifted LO signal from the LO signal, the third phase shifted LO signal having a coarse phase shift; phase shifting the third phase shifted LO signal to generate fine phase shifted LO signals each having a fine phase shift; and selecting a first fine phase shifted LO signal and a second fine phase shifted LO signal of the fine phase shifted LO signals, the second fine phase shifted LO signal substantially in phase quadrature to the first fine phase shifted LO signal, and applying the first fine phase shifted LO signal and the second fine phase shifted LO signal to a demodulator, thereby maintaining stability of the transmitter via time domain phase adjustments in the Cartesian feedback loop.