A new RF architecture for cesium frequency standards

A novel RF chain is described which overcomes many of the limitations of previous RF chains. The new architecture greatly reduces the four main problems in existing RF chains: excessive spurious sidebands, temperature-induced phase instability, inadequate isolation of internal and external subsystems, and significant modulator distortion. The cesium standard realizes higher performance by utilizing amplitude modulation in addition to frequency modulation and controls the RF level with a servo loop based on atomic interactions. The RF chain described implements these techniques. It also has sufficient available drive power for the beam tube to allow considerably lower Ramsey cavity Q