Generation device and method for high-purity very high frequency signal

Abstract

The invention provides a generation device for a high-purity very high frequency signal. The generation device comprises a low noise reference source, a power divider, a direct digital synthesizer, a mixer, a single-pole double-throw switch, a high pass filter, a low pass filter, the single-pole double-throw switch and a programmable frequency divider. According to the device, on the basis of the direct digital synthesizer (DDS for short), through adoption of a method of carrying out mixing with the high-purity very high frequency signal and then carrying out frequency division, under the condition of ensuring phase noise and frequency resolution advantages, spur suppression indexes are optimized, and an application range of a DDS circuit is expanded. According to the device, through flexible setting of the DDS and a frequency division ratio of the programmable frequency divider and through flexible selection of a mixing direction, the signal output frequency may reach hundreds of megahertzs, or even gigahertzs when the relatively small frequency division ratio is selected. Compared with a traditional frequency synthesis mode, the device has the advantages that under the condition that the phase noise and spur suppression indexes are very excellent, a frequency range of a synthesized signal is expanded from original dozens of megahertzs to hundreds of megahertzs.

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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