Research On The Temperature Compensation Oscillators Of LGS With Low Phase Noise

Crystal Oscillator, be called for short:Crystal or Chip, has been widely applied in many fields of electronic communication technology, which tends to be more compact, thin and chip-based and "three high and two low", means:high precision, high stability, high frequency and low power, low phase noise, in the future development. Conventional crystal oscillator is a kind of resonant device, produced by silica crystals (quartz) because of the piezoelectric effect. Because of the characteristics of quartz crystal itself, there is a big shift in the temperature-frequency, especially in some high frequency, high stability occasions, the general temperature compensation also cannot be good to meet application requirements, So to find a new material to replace quartz crystal is imperative. On this basis, this paper proposes a new type of material relatively better, called langasite, short for LGS, Comparative analysis of the frequency-temperature characteristics of LGS and quartz and other relevant characteristics, and compares several of the more common temperature compensation technology, finalized the crystal material and compensation programs.Repeated studies by many domestic and foreign scientists, shows that in addition to the better piezoelectric characteristics and temperature stability characteristics inherited from quartz crystals, it also has a relatively larger electromechanical coupling coefficient, smaller device insertion loss and a wider bandwidth.On the other side, traditional microcomputer temperature compensation technology does not use more advanced processor in hardware, cause the great limitations in the processor resources, and cannot implement complex temperature compensation algorithms, while the temperature unit separate from the processor, analog to digital conversion unit will increase the artificial error. The relative lack of complete control algorithms in the software, always lead to reboot the system, download the program on each experiment, and make the test become more difficulty and need more steps.With the rapid development of computer technology, more and more common for embedded applications, emerging new embedded microprocessors and the performance has become more powerful, integrated on-chip resources have become more and more rich also. This selection is STM32f103rc microprocessor, which is based on ARM’s Cortex-M3 core, with more than 12 of the A/D, D/A module, rich hardware debug interface and peripheral I/Os, combining with a small, stable, well-functioning domestic open-source embedded real-time operating system, called:RT-thread, for online real-time control function, calculating compensation voltage required by a variety of temperature compensation algorithm preferentially on the PC side, thus avoiding repeated download the program, greatly reducing the experimental procedures and improve the intelligence, and also reducing the errors of the system to a certain extent.In summary, this paper uses a new langasite crystal oscillator, combining with more advanced temperature compensation system, greatly improving the accuracy, and even can meet some of the occasions with the stringent accuracy requirements.