crystal oscillator

Abstract

The present application discloses a crystal oscillator, including: a crystal; an oscillator circuit, including a first oscillator transistor and a second oscillator transistor, wherein the first oscillator transistor and the second oscillator transistor are used for starting the crystal Oscillating and maintaining oscillation to provide transconductance; a first drive circuit, used to generate a stable reference current; and a second drive circuit, used to provide an operating voltage for the oscillating circuit, and make the first oscillate according to the reference current Working currents of the transistor and the second oscillating transistor are stable currents, wherein the working voltage is used to control the first oscillating transistor and the second oscillating transistor to work in a sub-threshold region.

Description

technical field [0001] The embodiments of the present application relate to the field of circuits, and more particularly, to a crystal oscillator. Background technique [0002] Pierce oscillator (Pierce oscillator, or Pierce crystal oscillator) is a crystal oscillator using an inverter structure, two metal oxide semiconductor field effect transistors (Metallic Oxide Semiconductor Field Effect Transistor, MOSFET) in the Pierce oscillator Both contribute to transconductance, which is beneficial to reduce the power consumption required to sustain oscillation. However, the Pierce oscillator has some problems. The bias current of the two MOS tubes is affected by the gate-source voltage V of the MOS tubes. GS Influence, and the sum of the gate-source voltages of the two MOS transistors is the power supply voltage V DD , so if V DD When larger, the V of the MOS tube GS It must also be large, which may lead to serious high-order effects. The problem is that although the power co...

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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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