High performance crystal oscillators for space applications

A family of high performance oven-compensated quartz crystal oscillators has been developed for military and space applications. The devices use precision SC-cut quartz resonators manufactured from Hirst-grown High Purity Quartz (HPQ), which is radiation resistant, and sophisticated crystal ovening techniques including the use of miniature dewars or, most recently, direct-heating of the quartz element. The oscillators exhibit high frequency stability, low phase noise, low power consumption and are very compact. The design process includes acoustic/waveguide modelling of the quartz resonator, thermal simulation of the selected oven configuration, and mechanical/stress modelling of the resonators, dewar, and overall assembly, with due regard to the environmental requirements. The in-house manufacturing capability includes the growth of HPQ, resonator manufacture, electronics assembly and oscillator integration. Oscillators are characterised extensively using comprehensive specialised facilities, for example, a dedicated ageing facility, vibration and g-sensitivity equipments. Several novel high performance oscillators have been developed including designs for extremely demanding space applications and twelve devices are already operating successfully in orbit.