一种频率稳定的低功耗振荡器电路设计

Circuit design of a low power oscillator with stable output frequency

设计了一种频率稳定的低功耗张弛振荡器电路。采用恒流源对电容两端同时充电和放电,然后将电容两端电压送入后级比较器进行判决,使得输出频率只与恒流源电流、电容以及比较器比较窗口相关。该电路采用GSMC 0.18μm CMOS工艺,在5 V电源电压以及室温条件下仿真,输出频率为123.6 kHz,平均电流消耗为2.67μA;在2 V～5.5 V电源电压和-40℃-+85℃的温度变化范围内,输出频率精度在-6.5%-1.3%范围内。

A Low-power relaxation oscillator with stable output frequency is presented in this paper. The method that the ca- pacitor is charged and discharged on its both ends is adopted. Since the voltages on both ends of the capacitor are used as the in- puts of comparator, the output frequency of the oscillator is only related to the bias current, the value of the capacitor and the hysteresis window of the comparator. The oscillator has been implemented in GSMC 0.18 I, zm CMOS process. The simulation results show that the oscillator only consumes 2.67 IxA with the output frequency of 123.6 kHz at a 5 V power supply and room tempera- ture. And the output frequency error is within -6.5%~1.3% when the supply voltage varies from 2 V to 5.5 V, as well as the temperature changes from -40 ℃ to 85 ℃.