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Crystal oscillator

  • US 9,030,265 B2
  • Filed: 08/13/2010
  • Issued: 05/12/2015
  • Est. Priority Date: 08/14/2009
  • Status: Active Grant
First Claim
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1. A crystal oscillator that generates an output oscillating signal by a crystal, the crystal oscillator comprising:

  • a first pad and a second pad, coupled to two nodes of the crystal;

    an amplifier, coupled to the first pad, for amplifying a crystal oscillating signal received from the first pad and generating an amplifying signal, wherein the amplifier comprises;

    a first transistor, having a first gate for receiving the crystal oscillating signal, having a first source coupled to a first operating voltage;

    a second transistor, having a second drain coupled to a first drain of the first transistor, having a second source coupled to a second operating voltage;

    a third transistor, having a third gate coupled to a second gate of the second transistor, having a third source coupled to the second operating voltage; and

    a fourth transistor, having a fourth drain coupled to a third drain of the third transistor, having a fourth source coupled to the first operating voltage, wherein the second and the third transistors form a current mirror circuit, wherein the first and the fourth transistors are implemented by NMOS transistors and the second and the third transistors are implemented by PMOS transistors; and

    an inverter, coupled to the amplifier, for inverting the amplifying signal and generating the output oscillating signal,wherein the amplifier has a first power consumption, the inverter has a second power consumption, and the first power consumption is smaller than the second power consumption.

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