一种高精度RC振荡器的设计

Design of a High Precision RC Oscillator

提出了一种基于CSMC 0.25μm CMOS工艺、输出高精度方波信号的低成本RC振荡器。采用正负温度系数电阻的线性叠加,产生不受温度影响的充电电流,消除了温度对精度的影响。增加修调电容,补偿工艺偏差对精度的影响,实现高精度的振荡输出。采用Spectre对电路进行温度扫描和电压变化仿真,结果表明在宽温度范围(-55～125℃)和宽电源电压范围(2.7～5.5 V)得到了非常稳定的振荡输出,受温度影响的频偏最大为1%,受电源电压变化的频偏仅为0.26%,适合电源管理芯片应用。

A low-cost RC oscillator based on CSMC 0.25 μm CMOS process and outputting high-precision square wave signal is proposed.The design uses a linear superposition of positive and negative temperature coefficient resistors to generate charge currents that are not affected by temperature,eliminating the effect of temperature on the accuracy and achieving high-precision oscillation output.Using Spectre to perform temperature sweep and voltage output is obtained over a wide temperature range(-55~125℃) and a wide power supply voltage(2.7~5.5 V).The maximum frequency deviation due to temperature is 1%,the frequency deviation of the power supply voltage change is only 0.26%,suitable for power management chip applications.