Very low power consumption, ultra low phase noise, miniature conventional OCXO

Battery powered equipment, whether instrumentation, underwater exploration, or military require high performance frequency sources with very low power consumption for obvious reason. Current state of the art in the area of very low power consumption OCXO [1]., [2]. employs evacuation of the entire (or almost entire) electronic circuit with crystal resonator in metal enclosure and internally heating the content. Although achieving the goal of significant reduction in power consumption (60-80 %), this approach has some serious drawbacks. The phase noise performance of one of the implementations is average at best, of another - is outright poor. Evacuation of the entire OCXO requires very complex and tedious processes, since any minute contamination can destroy deep vacuum, needed for device to operate. The availability of die semiconductor components, a necessity for inside the vacuum, is very limited. The devices are susceptible to exposure of elevated temperatures, which might induce internal outgassing and deterioration of vacuum level. The goal of this work was to create a device, which would eliminate above mentioned drawbacks i.e. employ conventional heating technique, use off-the shelf widely available components, have comparable to evacuated devices power consumption and size, and exhibit superior phase noise performance. The goal was achieved by implementing special thermal insulation technique, and NELs ULPN technology in 20×20×10 mm package. While the steady state power consumption at room temperature is less than 250 mW, the phase noise at 10 Hz offset at <;-145 dBc/Hz is better by 20 to 45 dBc than published specifications, and at -174 dBc/Hz, by 10 to 30 dBc on the floor.