| 摘要 |
A fast wake-up crystal oscillating circuit includes: a crystal oscillator for generating oscillation signal, an amplifier set, a feedback resistor, first and second triggers and an amplifier switch logic. The amplifier set amplifies the oscillation signal. The feedback resistor supplies DC operation bias to the amplifier set. The first trigger has an input connected to the output of the amplifier set so that the first trigger is triggered by the amplified oscillation signal to generate a first clock. The second trigger has an input connected the output of the amplifier set so that the second trigger is triggered by the amplified oscillation signal to generate a second clock, wherein the second trigger has a hysteresis voltage higher than a predetermined value. The amplifier switch logic is connected to the second trigger to gradually decrease the amplification of the amplifier set when detecting that the second trigger generates the second clock.
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