关键词: RC振荡电路, MCU, 低功耗, 高精度

Abstract: With the development of the internet of things, smart home and other industries, the demand for low-power micro-control unit (MCU) products is increasing. A step-down voltage, adjustable frequency, low-power, high-precision 16 MHz RC oscillator circuit is proposed for low-power MCU product requirements. The circuit is designed with the operating characteristics of the CMOS sub-threshold region, which effectively reduces the operating current; MCU low-power designs mostly support step-down operation. In order to ensure the accuracy of the output frequency of the oscillation circuit when the operating voltage is reduced, the built-in low power consumption and low dropout regulator (LDO) provides a stable operating voltage for the RC oscillator circuit. In addition, due to the process, temperature, voltage and parasitic effects, the actual output frequency deviation is large, the RC oscillator circuit is equipped with 8-bit FM control bit, which can be controlled by the FM control bit to recall the ideal frequency. The circuit is designed based on the 0.11 μm CMOS process, and the circuit is simulated using Cadence Spectre. The simulation results are as follows: the operating voltage varies from 1.6 V to 3.6 V, and the accuracy deviation of the output frequency of the oscillation circuit is from -0.48% to +0.2 %, the temperature changes within the range of -40-85 ℃, the accuracy deviation of the output frequency is -0.24%-+0.18%, after stable operation, the total current is 82.2 μA, the minimum power consumption is only 131.5 μW, and the frequency is adjustable within -32.84%-+33.47%. Simulation results show that the RC oscillator circuit is very suitable for integration into low-power MCU chips due to its advantages of low power consumption, high precision, and adjustable frequency.

Key words: RC oscillator circuit, MCU, low power consumption, high precision