Takeo Oita

Temperature Coefficients Improvements of VHF Oscillator Circuit for OCXO

This paper presents the improvements of the temperature coefficient of the VHF oscillator circuit for OCXO. The solution for this discrepancy, not only to regulate the temperature precisely, but also the temperature coefficients of oscillator loop itself should be considered and reduced for better frequency-temperature performance to get higher frequency stability for the OCXO.

Dual mode SC-cut crystal oscillator

The simultaneous dual mode oscillation circuit of the 5 MHz 3/sup rd/ overtone SC-cut crystal is designed using mode-selective linear phase crystal filters, for each C and B mode. The perturbable dual mode oscillation has been successfully eliminated over the temperature range from -20/spl deg/ C to +90/spl deg/ C. Temperature regulation is also achieved using B mode oscillation frequency which provides the temperature information of the SC-cut quartz crystal itself. Over the temperature range of -20/spl deg/ C to +70/spl deg/ C, the temperature of the SC-cut crystal has been locked within /spl plusmn/0.002/spl deg/ C converted by the heat frequency between C and B modes. The total power consumption at supply voltage of 12V, is less than 2.4W at +25/spl deg/ C in still air.

Combination of FEM/Harmonic Balance analysis of OCXO

Combination of FEM for thermal analysis and Harmonic Balance oscillation analysis can achieve the highly frequency/temperature stable OCXO such as a few parts per billion frequency/temperature performance for the wide temperature range by simple single oven. This design method basically has been applied to the new OCXO for the LTE(Long Term Evolution)base-station of the next generation of the mobile communication network.