一种应用于MCU的低温漂RC振荡器设计

Design of a low temperature drift RC oscillator for MCU

针对高稳定性MCU的应用需求,设计了一种低温度灵敏度的RC振荡器。采用平均电压反馈电路降低比较器延迟对振荡器输出频率的影响,采用温度补偿技术补偿温度对振荡器输出频率的影响,实现RC振荡器高稳定性输出。设计了一种选频网络,实现宽频率范围内高精度输出,满足MCU对多种时钟频率的需求。RC振荡器基于SMIC 110 nm CMOS工艺设计,并完成Cadence Spectre后仿真验证。结果表明,在1.2 V电源电压、TT工艺角、27℃室温环境下,RC振荡器输出频率为16 MHz,动态功耗为47μW;在1~1.3 V的电源电压变化范围内,输出频率的变化范围在±0.19%以内;在-30~120℃温度变化范围内,输出频率的变化范围在±0.13%以内。同相似结构RC振荡器相比,该RC振荡器的输出频率受温度影响较低,稳定性较高,适合高稳定性MCU的应用。

Aiming at the application requirement of high-stability MCU,a RC oscillator with low-temperature sensitivity was designed.The oscillator utilized a voltage averaging feedback circuit to reduce the impact of the delay of the comparator on the output frequency,and the temperature compensation technology was employed to compensate the temperature influence on the output frequency so as to achieve high-stability output.A frequency selection network was designed to achieve highprecision output in a wide frequency range to meet the needs of MCU for a variety of clock signals.The oscillator was implemented in SMIC 110 nm CMOS technology and analyzed with Cadence Spectre simulator.Post-layout simulation results show that the output frequency of RC oscillator is 16 MHz and the dynamic power consumption is 47μW at 1.2 V power supply voltage,process angle TT and room temperature;In the power supply voltage ranges from 1 V to 1.3 V,the output frequency of RC oscillator changes within±0.19%;When the temperature changes from-30℃to 120℃,the output frequency of the RC oscillator changes within±0.13%.Compared with other oscillators with the similar structure,the output frequency is less affected by temperature and has higher stability,which is suitable for high-stability MCU applications.