Method to pre-charge crystal oscillators for fast start-up

摘要

A method and apparatus for charging a crystal oscillator are provided. A voltage generating module outputs a ramp voltage signal to a ring oscillator. The ring oscillator generates and outputs a waveform based on the ramp voltage signal. The ramp voltage signal facilitates the ring oscillator to output the waveform at a frequency that varies with time, wherein the varying frequency is within a frequency range of the crystal oscillator. An inverter generates a digital input signal based on the waveform. The digital input signal is sent to an input of the crystal oscillator for charging the crystal oscillator. A feedback module outputs a feedback signal based on the digital input signal, wherein the feedback signal controls the voltage generating module to generate a fixed voltage signal that facilitates the ring oscillator to output the waveform at a frequency that is equal to a resonance frequency of the crystal oscillator.

主权项

1. An apparatus for charging a crystal oscillator, comprising:
a voltage generating module configured to output a ramp voltage signal; a ring oscillator configured to output a waveform based on the ramp voltage signal, wherein the ramp voltage signal facilitates the ring oscillator to output the waveform at a frequency that varies with time, the varying frequency being within a frequency range of the crystal oscillator; an inverter configured to generate a digital input signal based on the waveform, wherein the digital input signal is sent to an input of the crystal oscillator for charging the crystal oscillator; a feedback module configured to output, based on the digital input signal, a feedback signal to the voltage generating module, wherein the feedback signal controls the voltage generating module to output a fixed voltage signal that facilitates the ring oscillator to output the waveform at a frequency that is equal to a resonance frequency of the crystal oscillator.