Crystal oscillator

Abstract

The present invention discloses a crystal oscillator. The crystal oscillator comprises: a crystal, an oscillating circuit, a first driving circuit, and a second driving circuit, wherein the oscillating circuit comprises a first oscillating transistor and a second oscillating transistor; the first oscillating transistor and the second oscillating transistor are used for providing transconductance for oscillation starting of the crystal and maintenance of oscillation; the first driving circuit is used for generating a stable reference current; and the second driving circuit is used for supplyingan operating voltage to the oscillating circuit, and enabling the operating current of the first oscillating transistor and the second oscillating transistor to be a stable current according to the reference current; and the operating voltage is used to control the first oscillating transistor and the second oscillating transistor to operate in a subthreshold region.

Description

technical field [0001] The embodiments of the present application relate to the circuit field, and more specifically, relate to a crystal oscillator. Background technique [0002] The Pierce oscillator (Pierce oscillator, or Pierce crystal oscillator) is a crystal oscillator using an inverter structure. Two metal oxide semiconductor field effect transistors (MetallicOxide Semiconductor Field Effect Transistor, MOSFET) in the Pierce oscillator Both contribute to the transconductance, which is beneficial to reduce the power consumption required for sustaining oscillation. However, there are some problems with the Pierce oscillator. The bias current of the two MOS tubes is affected by the gate-source voltage V of the MOS tubes. GS , and the sum of the gate-source voltages of the two MOS transistors is the power supply voltage V DD , therefore, if V DD When larger, the V of the MOS tube GS It is also bound to be large, which may lead to serious high-order effects. The proble...

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Problems solved by technology

However, there are some problems with the Pierce oscillator. The bias current of the two MOS tubes is affected by the gate-source voltage V of the MOS tubes. GS , and the sum of the gate-source voltages of the two MOS transistors is the power supply voltage V DD , therefore, if V DD When larger, the V of the MOS tube GS It is also bound to be large, which may lead to serious high-order effects. The problem is that although the power consumption of the MOS tube is large, in fact the MOS tube does not provide enough transconductance, which is not conducive to the rapid start-up of the crystal.

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