A device and method for generating a high-purity VHF signal

Abstract

The invention proposes a high-purity VHF signal generation device, including: a low-noise reference source, a power divider, a direct digital frequency synthesizer, a mixer, a single-pole double-throw switch, a high-pass filter, and a low-pass filter , single-pole double-throw switch, programmable frequency divider; the present invention is based on direct digital frequency synthesizer (abbreviated as DDS), by first mixing with a high-purity reference signal, then frequency division method to ensure the advantages of phase noise and frequency resolution Under the circumstances, optimize the spurious suppression index and expand the application range of the DDS circuit. The present invention flexibly sets the frequency division ratio of the DDS and the programmable frequency divider and selects the mixing direction, so that the frequency of the signal output can reach hundreds of megahertz, and a smaller frequency division ratio can even reach gigahertz. Compared with In the traditional frequency synthesis method, the frequency range of the synthesized signal of the present invention is extended from tens of megahertz to hundreds of megahertz under the condition that the phase noise and spurious suppression indexes are very excellent.

Description

technical field [0001] The invention relates to the technical field of testing, in particular to a high-purity VHF signal generation device, and also to a high-purity VHF signal generation method. Background technique [0002] The phase noise and frequency resolution of the local oscillator of the signal analyzer determine the technical indicators of the phase noise level and frequency resolution of the signal analyzer, and these two indicators are important indicators that reflect the analyzer's ability to analyze weak signals. The signal analyzer tunes the minimum step frequency of the phase detection reference signal of the local oscillator to determine the frequency resolution of the signal analyzer. Because the phase noise index of the signal analyzer will definitely not be better than the index of the reference signal, the phase noise level of the phase detection reference signal is a limiting factor of the phase noise index of the signal analyzer. Improving the phase...

AI Technical Summary

Problems solved by technology

The phase noise level and spurious spurs of the fractional ring itself cannot meet the requirements of high-performance measuring instruments, and it is necessary to further reduce the phase noise level after frequency division.

The oscillation frequency of the fractional loop VCO, that is, the operating frequency of the fractional loop is several hundred megahertz to several gigahertz. After frequency division, the signal frequency of ultra-low phase noise, low spurious, and high resolution is generally tens of megahertz; if passed Reduce the frequency division ratio and increase the frequency, and the phase noise and spurious levels will become worse

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