High stability, miniature OCXOs for severe environmental conditions. High temperature effects on aging and retrace characteristics

A.R. Electronique has developed a new generation of high stability compact OCXOs, especially designed for tactical, on board avionic/missile application or geophysical use. These oscillators are built with SC cut, low g sensitivity resonators, associated with fully integrated electronics (monolithic ASIC). The extremly severe environmental requirements induces a hard mounted resonator structure, fully compatible with high stability. The extended temperature range (up to +115°C) involves a temperature regulation on the 2^nd turn over point of the SC cut thermal curve, at about +120°C. After giving the environmental conditions and associated electrical requirements, the paper describes the crystal resonator, oscillator and assembly designs. Practical experimental results are showed, including: resonator´s g sensitivity measurements; phase noise under high level random vibrations (50g/2000 Hz); frequency stability versus wide temperature range (-40, +120)°C; fast warm-up (frequency, power); internal temperature gradient effect. The aging and retrace behavior is pointed out : the effect of very high ovenized temperature is presented, based on comparative long term stability measurements done on first and second turn-over point (characterizations on 18 months). Some other parallel oscillator developments, based on the use of the same type of high reliability resonator are briefly described