The Microcomputer Compensated Crystal Oscillator Based On TLC320AC02I

The rapid development of modern electronics technology demands much higher frequency stability, smaller package and lower power consumption on quartz crystal oscillator. For adapting this situation, a novel kind of microcomputer compensated crystal oscillator (MCXO) is successfully designed which uses a 14-bit AD/DA digital processor TLC320AC02I and a single-chip-microcomputer AT89C4051 as its core. In the thesis, it is introduced in detail that the operating principle, the system structure and the operating program of the MCXO. For TLC320AC02I, the thesis describes its data format setup protocol in primary and secondary communication serial, the method to startup its internal A/D and D/A converter synchronously, and the realization of its power-down mode. The phase and amplitude balance condition for colpitts oscillator circuit are analyzed and deduced from the concept of "negative resistance", which has been used to design the practical oscillator circuit. And Pt resistor is used as the thermistor for the temperature sensor. Especially, an innovative on-line calibration method for MCXO is presented, with which the whole calibration process is controlled with digital system, and can be operated after all packaging is completed, so as to largely improve the temperature compensated precision, realize the best optimized match on calibration mode and operating mode, and accord with the technical requirements for mass production. Using microcomputer as the key device, the linear interpolation arithmetic has been developed to give the best fit to the crystal's 3^rd order polynomial frequency versus temperature curve, the crystal ageing can be modified automatically, and the MCXO's frequency can be fine adjusted by connecting a simple keypad to its communication I/O pin. At the same time, by optimizing the design on both hardware and software, the size and power consumption of the system are largely decreased. The whole MCXO is encapsulated by resistance weld to improve the system performance on anti-electromagnetism interference and adapting the ambient. Finally, the samples were strictly tested in Japanese Systec Research Inc. and Hunan University. The achieved results are listed in the end of the thesis: frequency-temperature stability ≤±2× 10^-7(-40℃ + 85℃), size: 35×23 × 10mm³, average power consumption ≤50mW.So far, there is yet a widening gap between the domestic and the developed country on the research and manufacture level of MCXO, and it has not been reported...