An ultra-miniature Rb atomic clock compatible with OCXO

This paper shows a traditional Rubidium atomic clock - XHTF1031. The incorporate lamp and ultra-miniature waveguide cavity introduced in the physics package is the main means to downsize the volume of the clock; the electronics consisting of 6.8GHz direct synthesizer and digital servo system is to enhance the automatic functions which ensure massively fabrication available with low costs. At all, the clock has the physical dimensions of a ovenized crystal oscillator (OCXO), measuring 51mm×51mm (2´×2´) and standing at a mere 25mm (1´). The Allan deviation of instability is 3E-11/s; the temperature coefficient is 3E-10 in the range of -20~60°C the frequency aging is below 5E-12/d. The clock has the same dimension and pins´ definitions with OCXO used in telecom, but higher performance, and would be popularly used in telecom equipments and base-stations instead of OCXO in future.