Abstract: A RC charging time zero crossing invariant oscillator is designed to provide high precision and high stability clock signals insensitive to voltage and temperature. This paper analyzes and deduces the characteristics that the time of zero crossing voltage does not vary with the power supply voltage in the process of RC charging, and adopts the temperature compensation technology to ensure that the time of zero crossing voltage does not vary with the temperature to the maximum extent. The simulation results show that the oscillator can output 2 MHz stably, the frequency fluctuation from 2.5 V to 5.5 V is less than 1%, the temperature fluctuation from -40 ℃ to 125 ℃ is less than 1%, and the maximum current under PVT condition is less than 150 μA.

Key words: RC charging time zero crossing invariance, high precision, high stability, oscillator