Main circuit of quartz crystal oscillator

Abstract

The invention applies to the field of oscillation integrated circuits, and provides a main circuit of a quartz crystal oscillator. The main circuit comprises a frequency-selecting network of a three-point oscillator consisting of an oscillating transistor and two capacitors, a bias voltage generation circuit, a reference level generation circuit connected with the bias voltage generation circuit, as well as a peak-value detection-comparison circuit, wherein the main circuit also comprises a feedback gain control circuit which is connected with the reference level generation circuit, a the peak-value detection-comparison circuit and the frequency-selecting network; the feedback gain control circuit is used to automatically control the gain of an oscillation transistor in the frequency-selecting network till the oscillator achieves balance when output signals of the frequency-selecting network exceed reference level generated by the reference level generation circuit and the peak-value detection-comparison circuit; and the frequency-selecting network is connected with the reference level generation circuit and the peak-value detection-comparison circuit through blocking capacitors.

Description

technical field [0001] The invention belongs to the field of oscillating integrated circuits, in particular to a quartz crystal oscillator main circuit. Background technique [0002] Quartz crystal integrated circuit oscillator is an important integrated module of radio frequency communication system and digital circuit. Because of its high no-load quality factor and extremely small access coefficient, it has high frequency stability and low phase noise. , which can provide a very accurate clock signal reference. [0003] figure 1 It shows the composition of a typical capacitor three-point Colpitts structure parallel quartz crystal oscillator main circuit, which includes quartz crystal J1, capacitors C1 and C2, inverting amplifier, bias voltage generation circuit, reference level generation circuit and peak detection comparison circuit. At the oscillation frequency, the quartz crystal J1 is equivalent to an inductance, thus forming a capacitive three-point LC oscillator ...

AI Technical Summary

Problems solved by technology

[0005] The purpose of the present invention is to provide a main circuit of quartz crystal oscillator, which aims to solve the problem that the output signal waveform will be distorted without external gain control under the condition of large signal operation of the oscillator circuit.

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