An ultra-miniature rubidium frequency standard with two-cell scheme

An ultra-miniature, general-purpose rubidium gas cell frequency standard with a two-cell scheme has been successfully developed, with the aim of developing one of the smallest atomic frequency standards in the world. The new rubidium frequency standard embodies new electrical and structural design features, such as a miniature physics package incorporating a cylindrical TE111 microwave cavity in which an integrated filter-resonance cell is entirely loaded, a 10MHz ultra-miniature slave oscillator using voltage controlled TCXO(VC-TCXO) technologies established in the mobile telecommunication field, state of-the-art electronic circuit/assembly technologies, and a simplified, fabrication-oriented structure. As a result of these features, the new rubidium standard has an extremely small volume (310 cc), light weight (700 grams), and a wide operating temperature range (-10 degree C to +60 degree C). A series of measurements have been made to characterize the performance of the new rubidium frequency standard. In spite of the substantial reduction in size, it exhibits excellent performance, comparable to that of existing high performance models of commercial rubidium frequency standards, including previous models which Fujitsu has developed. Presented in this paper are the details of the design concepts and electronic performance of this newly-developed frequency standard.