Frequency synthesis chain for the atomic fountain primary frequency standard

The frequency noise of the local oscillator may degrade the long-term stability of high-stability frequency standard; a simple evaluation of this effect is performed to optimize the design of a synthesizer to be used in Cs atomic primary frequency standard. A description of the microwave synthesis chain realized, which is suitable as a local oscillator for Cs atomic primary frequency standard, is reported. Phase noise spectra in the key points of the chain are also reported. The measured fractional frequency stability of the chain is better than 10/sup -17/ at one day.