小型化微处理机温度补偿晶体振荡器的研究

【作者】 安峡；

【导师】 黄显核；

【作者基本信息】 电子科技大学 ， 检测技术与自动化装置， 2006， 硕士

【摘要】 随着电子技术的飞速发展,频率高度稳定的晶体振荡器得到了广泛的应用,特别是温度补偿晶体振荡器(TCXO)更是广泛应用于通信、导航、雷达、测量仪表等电子设备中。在TCXO中,微处理机温度补偿晶体振荡器(MTCXO)是一种比较新型的数字式温度补偿晶体振荡器。本文研究了一种小型化微处理机温度补偿晶体振荡器。首先对石英晶体谐振器的频温特性进行分析,然后通过求解描述固体中弹性声波的Christoffel方程,得到其在切角Φ3 =0 ,Φ1=35 6′处也即AT切石英晶体谐振器的频率温度特性曲线,这是本文进行温度补偿的理论依据。并由此设计了振荡电路的实际电路。接着分析了MTCXO的温度补偿原理,介绍了系统的基本结构及工作原理,器件选择和电路设计,以及微处理器ADμC814的在线调试系统。之后文章详述了单片机的软件程序设计。由于微处理器ADμC814功能强大,内部集成了温度传感器、ADC、DAC和CPU等部分,使得系统可以充分发挥软件的优势。在设计中采用软件以及软硬相结合的方法代替大量的硬件电路,这样就大大减少了晶体振荡器的体积及制造成本。最后进行实验,通过对实验数据的分析,本文提出了一种改进方案,即采用外部温度传感器DS18B20,避免内部传感器的精度不高及干扰带来的误差,能在一定程度上改善系统输出频率。更多还原

【Abstract】 With the quick development of electronic technology, high-stability crystal oscillator is being used more and more widely. Especially, temperature-compensated crystal oscillator (TCXO) is commonly used in electronic equipments such as communication, navigation, radar, measure instruments etc..Therein, microprocessor temperature compensation crystal oscillator (MTCXO) is a comparatively new-type digital compensated crystal oscillator. In this paper, a type of miniature microcomputer compensated crystal oscillator is studied. First, the frequency-temperature (F-T) characteristic of quartz crystal resonator is analyzed. Then, the frequency-temperature (F-T) characteristic curve of AT-cut quartz crystal resonator (at cut angle:Φ3 =0 ,Φ1=35 6′) is obtained based on analyzing the Christoffel equation describing flexibility sound wave in solids, which serves as the theory basis used for temperature compensated, from which the actual circuit of oscillatory circuit is designed. Moreover, the compensation principles of MTCXO are dicussed, and the basic structure and operating principles of the system are introduced systematically. Forethermore, MCU software design is presented detailedly.This powerful microprocessor ADμC814 integrates temperature sensor, ADC, DAC, and MCU, so that it lets the system make full use of the software. In the process of design, a method, which combines the software with the hardware, is used to replace a large number of hardware circuits. Hence, it is beneficial for greatly reducing the size and manufacturing costs of crystal oscillators.Finally, based on the analysis of the experiment results, an improved scheme is put forward, that is, the application of the external temperature sensor DS18B20, which avoids the error caused by low precision of the internal sensor and interference and improves system output frequency to some degree.更多还原