Frequency deviation control crystal oscillation circuit

Abstract

The invention discloses a frequency deviation control crystal oscillation circuit. The frequency deviation control crystal oscillation circuit comprises a NMOS tube N1, a frequency deviation control circuit which is connected between the grid and the drain of the NMOS tube N1, the resistance Rf and the frequency selective network, and a programmable current source that connects the input end of the frequency deviation control circuit; the output end of the frequency deviation control circuit is connected with the input end of an external frequency deviation detection module, and the input end of the programmable current source is connected with the output end of the external frequency deviation detection module; the frequency deviation control circuit receives the oscillation signal, adjusts the frequency deviation of the signal according to the control parameters output by the programmable current source, and outputs the adjusted signal; and the programmable current source sets the corresponding control parameters according to the configuration parameters fed back by the external frequency deviation detection module, and outputs to the frequency deviation control circuit. According to the invention, the programmable current source sets the corresponding control parameters to the frequency deviation control circuit according to the size of the signal frequency deviation fed back by the external frequency deviation detection module, so that the adjusted signal frequency deviation is more in line with the demand of the user, and the output signal frequency is more stable.

Description

technical field [0001] The invention relates to the technical field of semiconductor integrated circuits, in particular to a frequency offset control crystal oscillation circuit. Background technique [0002] Quartz crystal itself has a piezoelectric effect, which shows the combination of the mechanical properties and electricity of the quartz crystal; the quartz crystal oscillator is a passive resonant device made of the piezoelectric effect of the quartz crystal, because the quartz crystal has Very high quality factor, so the quartz crystal plus the oscillator circuit can produce a frequency accurate and stable oscillation waveform with an accuracy of up to 10 -5 —10 -4 , and cheap, widely used in military, industrial, GPS and other fields. [0003] Such as figure 1 As shown, it is a Pierce crystal oscillating circuit. The capacitors C1 and C2 in the figure together with the quartz crystal form a frequency selection network. The NMOS transistor N1 is used as a gain ampl...

AI Technical Summary

Problems solved by technology

[0004] Because in this circuit structure, the output XOUT terminal loop has no feedback, so the clock signal output by the XOUT terminal has a large frequency deviation, which directly affects the stability of the oscillation frequency.

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