CIRCUIT FOR ADJUSTING FREQUENCY OF CRYSTAL OSCILLATOR

摘要

A circuit for adjusting frequency of a crystal oscillator includes a basic input output system (BIOS), a platform controller hub (PCH), a buffer, and a capacitor module with a number of capacitors. The crystal oscillator is connected to clock pins of the PCH. An input pin of the buffer is connected to the crystal oscillator. A first end of the each of the capacitors is connected to an output pin of the buffer. A second end of the each of the capacitors is grounded. The buffer includes two enable pins and a control unit controlled by the enable pins. The enable pins of the buffer receive a control signal from the PCH according to the BIOS, and control the control unit to appoint the corresponding capacitor of the capacitor module to be connected to the input pin of the buffer.

主权项

1. A circuit, comprising:
a basic input output system (BIOS) outputting a control signal; a platform controller hub (PCH) receiving and outputting the control signal outputted from the BIOS, the PCH comprising a first clock pin connected to a first end of a crystal oscillator and a second clock pin connected to a second end of the crystal oscillator; a buffer comprising an input pin, a plurality of output pins, a plurality of enable pins, and a control module, wherein the input pin is connected to the second end of the crystal oscillator, the plurality of enable pins receives the control signal from the PCH, to control the input pin to be connected to or disconnected from the corresponding output pins through the control module, according to a logic state of the control signal; a capacitor module comprising a plurality of capacitors, wherein a first end of each capacitor is connected to a corresponding one of the plurality of output pins of the buffer; a second end of each capacitor is grounded; when the input pin of the buffer is controlled by the control module to be connected to one output pin of the buffer, the capacitor connected to the output pin is connected to the second end of the crystal oscillator.