Development of a 5 MHz frequency difference pre-multiplier for a short term frequency stability bench of the oscillators

This paper reports the realization of a 5 MHz frequency difference x10 pre-multiplier, developed in the laboratory to replace an obsolete one. The principle we chose is to synthesize a 45 MHz and a 50 MHz from a reference signal and from the signal to be measured, and to subtract one to the other to generate a 5 MHz, whose precision on the measurement is increased by a factor 10. Obtained Allan variance sigma_y(tau) at 1 s is 5.10^-14 and output spectral density of phase noise floor is about -160 dBc/Hz at 5 MHz.