A Method of Generating High-precision Offset Frequency Based on Quadrature Phase Shift

By studying the principle of single side-band mixing, a new method based on quadrature phase shift for generating high-precision offset frequency was proposed. Different solutions of precision quadrature phase shift were designed for different frequencies, including combining analog quadrature splitter and wire delay for 10MHz, combining digital phase shift module using CPLD, digital delay line chip and wire delay for 10kHz. According to the design goal, the design parameters and requirements of narrow-band low-loss filter were analyzed. Finally, an offset frequency generator whose output frequency is 9.99999MHz was developed and an experiment system is constructed to test the performance of the high-precision offset frequency generator. According to the experiment results, the following conclusion can be drawn that the Allan deviation of the 9.99999MHz offset frequency generator is 4.03e-13 which is close to the frequency stability of 10MHz signal of Hydrogen Maser MHM-2010 of Sigma Tau corporation. The high-precision offset frequency generator can be used as a common source in dual mixer time difference and as a reference signal in beat frequency method.