A temperature compensated crystal oscillator based on analog storage method and its test system

Abstract

Analog storage (function storage) temperature compensated crystal oscillator (ASCXO) is low in price, simple in structure and high in precision. According to the similarity between cubic curve of crystal oscillator frequency control voltage-temperature sensing voltage and the voltage-time characteristics of sine waveform, the control voltage can be obtained through translating V T characteristics of sine waveform into V-V relationship. With compensation and increment regulation, the temperature compensated curve can be obtained. The test and regulation of the voltage curve are also described. ASCXO has a low demand on the accuracy of the temperature chamber, as is the case in MCXO. In the test process, we utilize measurement instead of control to simplify the equipment. When the temperature of chamber changes slowly the temperature sensing voltage and the frequency modification voltage of the oscillator are measured cyclically. Using a computer some special voltages are recorded and the reference temperature curve is obtained. After a temperature cycle experiment, the storage curve adjustment is done at room temperature. Using coincidence process of the curves the adjustment is completed by computer. One can also find out the accuracy of the oscillator at room temperature. This paper also describes some special demands upon the components. It is easy to obtain 10/sup -7/ or better frequency-temperature stability with ASCXO.