Ultralow phase noise reference signal generating device for frequency synthesizer

Abstract

The invention relates to an ultralow phase noise reference signal generating device for a frequency synthesizer. The reference signal generating device comprises a crystal oscillator, a first phase locked loop and a second phase locked loop which are in sequential connection. The first phase locked loop comprises a first phase discriminator, a first loop filter and a voltage-controlled crystal oscillator which are in sequential connection, wherein the voltage-controlled crystal oscillator is connected with a feedback input end of the first phase discriminator. The second phase locked loop comprises a second phase discriminator, a second loop filter and a voltage-controlled surface acoustic wave oscillator which are in sequential connection, wherein the voltage-controlled surface acoustic wave oscillator is connected with a feedback input end of the second phase discriminator. Phase noises of reference signals generated by the ultralow phase noise reference signal generating device are optimal values at different frequency deviation positions of each oscillator, and the reference signal at each frequency deviation position can acquire the optimal phase noise.

Description

technical field [0001] The invention relates to an ultra-low phase noise reference signal generating device, in particular to an ultra-low phase noise reference signal generating device for a frequency synthesizer. Background technique [0002] Phase noise is a very important technical index of a frequency synthesizer, and it has a great influence on the performance of the entire system to which the frequency synthesizer is applied. In the communication system, the phase noise will reduce the signal-to-noise ratio of the channel and increase the bit error rate; in the radar system, the phase noise will reduce the ability of the radar system to distinguish the target, that is, the improvement factor; in the receiver, the phase noise will Increase the effective noise figure of the receiver. [0003] In a direct frequency synthesizer, the phase noise of the output signal of the frequency synthesizer and the phase noise of the reference frequency satisfy the relationship of 20l...

AI Technical Summary

Problems solved by technology

[0007] The purpose of the present invention is to provide an ultra-low phase noise reference signal generator to solve the problem that the best phase noise cannot be obtained at each frequency offset when a single oscillator of a certain type or a certain frequency is used to generate a reference signal , to provide a reference signal for the direct frequency synthesizer that can achieve the best phase noise at each frequency offset

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