A Miniature Oven-Controlled Crystal Oscillator (OCXO) with ppt Stability over Temperature Using High-Order Polynomial Temperature Control

This work presents an ASIC-based miniature oven-controlled crystal oscillator (OCXO) with ppt (part-per-trillion) stability over ambient temperature from -40 to 85°C using high-order polynomial temperature control. The proposed OCXO integrates the high-order polynomial temperature control circuit in an IC, thus realizing ppt stability in a miniature 9mm x 7mm footprint. The high-order polynomial temperature control is applied to compensate the complicated non-linear frequency stability error over ambient temperature contributed from higher thermal loss due to miniaturized package and more sensitive thermal effect of integrated circuit. As a result, the proposed OCXO with ppt stability in a miniature footprint provides highly accurate synchronization reference for base station, distributed unit (DUs), and centralized units (CUs) that need longer holdover capability.