Low phase noise wideband microwave local oscillator source circuit and realization method thereof

Abstract

The present invention provides a low phase noise wideband microwave local oscillator source circuit which is formed by two phase-locked loops. The frequency division signal of a broadband voltage-controlled oscillator directly enters a phase detector to form phase-locked loops with a reference signal, and the preset of the whole loop is realized. Then through switch switching, the output signal of the voltage-controlled oscillator and the frequency doubling and frequency division of a sampling ring output signal are mixed, the phase locking is carried out again, and the function of a low noise is realized. According to the low phase noise wideband microwave local oscillator source circuit, a wideband VCO chip is used, the outputted frequency range is 3GHz to 10GHz, and the phase noise of a 10GHz signal can reach -120dBc / Hz@10kHz. According to the low phase noise wideband microwave local oscillator source circuit, while very low phase noise is obtained, the number of used devices is greatly reduced, a PCB space is saved, the volume is only 16cm by 9cm by 2cm, the debugging difficulty is reduced, and the power consumption is reduced.

Description

technical field [0001] The invention relates to the technical field of frequency synthesis, in particular to a low-phase-noise wide-band microwave local oscillator circuit and a method for realizing a low-phase-noise wide-band microwave local oscillator. Background technique [0002] Frequency synthesizers are widely used, such as in radar, communication, navigation and other fields, and are an important part of modern electronic systems. With the continuous development of electronic technology, various electronic systems have higher and higher requirements for the performance indicators of frequency synthesizers, such as frequency conversion time, phase noise, spurious, frequency range and other indicators. . Among them, phase noise is a key factor that determines the performance of the frequency synthesizer. Low phase noise performance can improve the improvement factor of the radar and improve the ability to detect signals in a strong background environment of the radar;...

AI Technical Summary

Problems solved by technology

[0007] In the existing broadband phase-locked loop circuit, most commonly used phase-locked loop solutions are built with integrated phase-locked loop chips and dedicated VCOs, which have the characteristics of simple circuit structure and low power consumption. However, due to the high frequency band and wide frequency range, Phase noise can not achieve good results

[0008] The commonly used phase-locked loop frequency synthesis technology uses the signal after the frequency division of the output signal as the feedback signal, and mixes it with the reference signal. The mixed signal is used as the input phase detection signal of the phase detector, and the phase noise index of the signal is poor. , the output frequency range is narrow

[0009] Direct digital frequency synthesis technology is limited by the highest available clock frequency of the device. The upper limit of the output frequency is not high enough to produce the output signal frequency of the radio frequency band. The use of the DAC device that is indispensable in this technology makes its output signal produce a comparison Many spurious signals affect the signal quality

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