A low phase noise broadband microwave local oscillator source circuit and its realization method

Abstract

The present invention proposes a low-phase-noise wide-band microwave local oscillator source circuit, which is composed of two phase-locked loops. The frequency-division signal of the broadband voltage-controlled oscillator directly enters the phase detector and the reference signal to form a phase-locked loop, realizing the whole The preset setting of the loop; then through the switch, the output signal of the voltage controlled oscillator is mixed with the frequency multiplication and frequency division of the output signal of the sampling loop, and the phase locking is performed again to realize the low noise function. The low phase noise broadband microwave local oscillator source circuit of the present invention adopts a broadband VCO chip, and the output frequency range is 3GHz‑‑‑10GHz, and the phase noise of the 10GHz signal can reach ‑120dBc / Hz@10kHz; the present invention obtains While the phase noise is extremely low, the number of components used is greatly reduced, and PCB space is saved. The volume is only 16cm×9cm×2cm, which reduces the difficulty of debugging and reduces power consumption.

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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