Design of a low temperature drift low power RC oscillator
In order to reduce the impact of temperature on MCU clock frequency and reduce MCU power consumption,a low power RC oscillator based on 0.18μm standard CMOS technology is designed.The capacitor is charged by adding PTAT(Proportional To Absolute Temperature)current and CTAT(ComplementaryTo Absolute Temperature)current,which temperature compensates the frequency of the oscillator.Reduce the effect of temperature on the output oscillation frequency.The low power subthreshold operational amplifier is used instead of the traditional comparator,which greatly reduces the power consumption of the oscillator.The current adjusting circuit is designed to improve the accuracy of the oscillator output frequency.The power supply voltage of the oscillator is 1.8 V,and when the process angle is TT,the output oscillation frequency is 231 kHz,and the static working current is 9.6 μA.When the temperature changes from-25℃to 125℃,the frequency variation range is within 1%,the temperature coefficient is 5.9×10-5℃-1,and the maximum working current is only 12 μA;When the power supply voltage changes by 0.1 V,the frequency variation range is within 1.8 kHz.