一种超低功耗RC振荡器设计

Design of an Ultra-Low Power Consumption RC Oscillator

基于SMIC 55 nm CMOS工艺,设计并制备了工作在1.2 V电源电压下的超低功耗RC振荡器。该振荡器主要包括运算放大器、压控振荡器（VCO）、基准电流源、低温漂电阻和可修调开关电容以及非交叠时钟产生电路。该振荡器用工作在亚阈值区的运算放大器和VCO取代了传统单比较器型RC振荡器中的比较器,显著降低了功耗;用开关电容取代了充放电电容,并且将输出时钟的频率转换成了阻抗,与参考电阻进行比较。利用负反馈环路锁定了输出时钟信号频率,从而得到了稳定的时钟信号。测试结果表明,1.2 V电源电压、27℃环境下,该RC振荡器的输出时钟信号频率为32.63 kHz,功耗为65 nW;在-10-100℃,其温度系数为1.95×10（-4）/℃;在0.7-1.8 V电源电压内,其电源电压调整率为3.2%/V。芯片面积为0.168 mm2。

An ultra-low power consumption RC oscillator under 1. 2 V power supply voltage was designed and fabricated based on SMIC 55 nm CMOS process. The oscillator mainly consists of the operational amplifier,voltage controlled oscillator（ VCO）,reference current source,low temperature drift resistor, repairable switching capacitor and non-overlapping clock generation circuit. The proposed oscillator replaced the comparator in the traditional single comparator RC oscillator with the operational amplifier and VCO working in sub-threshold region,which significantly reduced power consumption. The switched capacitors replaced the charge and discharge capacitors,and the output clock frequency was converted to the impedance,which was compared with the reference resistance. The output clock signal frequency was locked by the negative feedback loop,thus the stable clock signal was obtained. The test results show that the RC oscillator outputs a 32. 63 kHz output clock signal frequency while consuming65 nW at 1. 2 V supply voltage at 27 ℃. The temperature coefficient of the RC oscillator is 1. 95 ×10（-4）/℃ between-10 ℃ to 110 ℃. The supply voltage line sensitivity is 3. 2%/V between 0. 7 V to 1. 8 V. The chip area is 0. 168 mm2.