Local oscillator with non-harmonic ratio between oscillator and RF frequencies using XOR operation

摘要

A novel and useful apparatus for and method of local oscillator (LO) generation with non-integer multiplication ratio between the local oscillator and RF frequencies. The LO generation schemes presented are operative to generate I and Q square waves at a designated frequency while avoiding the well known issue of harmonic pulling. A synthesizer provides 4/3 the desired frequency f_RF. This frequency is divided by two to obtain in-phase and quadrature square waves at 2/3 f_RF. The in-phase signal is divided by two again to obtain in-phase and quadrature square waves at 1/3 f_RF. The signals are then logically combined using XOR operations to obtain I and Q branch signals containing spectral spurs. Since the spurs are located in non-disturbing bands, they can be filtered out resulting in the desired output signal.