Abstract—A low power CMOS crystal oscillator was proposed with high accuracy by tuning capacitors. Based on the analysis concerning power consumption, start-up time, and frequency stability of the crystal oscillator, an amplitude regulation circuit was employed to limit the current consumption. Simulation results showed the measured currents of 27 µA and 20 µA with and without the output stage under 1.5 V supply voltage, respectively. Index Terms—amplitude regulation, low power, quartz crystal oscillator. I