Patent ID: 7138881
Filing Date: 2006-11-21
Classification: H03B

Abstract:
1. A fast wake-up crystal oscillating circuit, comprising: a crystal oscillator for generating an oscillation signal; an amplifier set for amplifying the oscillation signal and generating an amplified oscillation signal at its output terminal so that the amplifier set has a maximum amplification when a power supply is applied; a feedback resistor connected in parallel with the amplifier set for supplying a DC operation bias to the amplifier set; a first trigger having an input terminal connected to the output terminal of the amplifier set so that the first trigger is triggered by the amplified oscillation signal to generate a first clock output, wherein the first trigger has a first hysteresis voltage; a second trigger having an input terminal connected the output terminal of the amplifier set so that the second trigger is triggered by the amplified oscillation signal to generate a second clock output, wherein the second trigger has a second hysteresis voltage higher than the first hysteresis voltage; and an amplifier switch logic connected to the second trigger to gradually decrease the amplification of the amplifier set when detecting that the second trigger generates the second clock output.