Research on High Precision Oscillator Design with Wide Power Supply Range

Abstract

In order to solve the problem of poor frequency stability of CMOS oscillator, a circuit structure of high-precision wide power supply range oscillator based on threshold voltage is proposed. The capacitor is charged and discharged by controlling the on-off of the MOS transisor to generate a clock signal with a duty cycle of 50%.The process trimming is realized by using the fuse resistor to control the current mirror trimming circuit. Based on $0.25 \mu \text{m} B C D$ process, the test results show that the center frequency of the clock signal is 36.5 kHz when the power supply voltage is 3V. The process trimming range is $54.14 \% \sim 219.18 \%$, and the trimming precision is $-0.82 \% \sim+2.53 \%$. Within $2 \text{V} \sim \mathbf{4 V}$ variation range, the frequency change coefficient is $0.97 \% / \text{V}$. Within the power supply voltage range of $1.8 \text{V} \sim 5.8 \text{V}$, the frequency change coefficient is 2.47%/V. The power supply voltage is in the range of $1.8 \text{V} \sim 12 \text{V}$, and the frequency variation coefficient is 1%/V, which has a wide power supply adaptability.