一种基于开关电容的高精度低温度系数振荡器

A High Precision and Low Temperature Coefficient Oscillator with Switched Capacitor

在分析传统环形振荡器的基础上,提出了一种基于开关电容的高精度低温度系数环形振荡器。采用了带开关电容电路的频率负反馈架构,使得输出频率的精度与其温度系数仅取决于外部设定电阻与片上电容,通过合理选择外部设定电阻,即可实现高精度、低温漂的时钟输出。设计的高精度低温度系数的环形振荡器采用0.6μm标准CMOS工艺设计。仿真结果显示,当输出频率为5 MHz时,输出频率误差≤1.74%,频率温度系数≤8.11×10^(-5)/℃。

Based on the analysis of traditional ring oscillators,and a high precision and low temperature coefficient oscillator with switched-capacitor is proposed.A frequency based negative feedback circuit with switched capacitor circuit was designed for the oscillator,in which the precision and the temperature coefficient of output frequency was only dependent on external resistor and integrated capacitor.With an appropriate chosen external resistor,a high precision clock with low temperature coefficient could be achieved.The circuit was designed and implemented in a 0.6μm standard CMOS process.The simulation results show that the frequency error is less than 1.74%and the frequency drift over temperature is less than 8.11×10^(-5)/℃when the output frequency is 5 MHz.