Wide-band agile low-phase noise frequency integrated generator

Abstract

The invention belongs to the technical field of frequency integrated generators, and particularly provides a wide-band agile low-phase noise frequency integrated generator, which comprises a high-stability crystal oscillator, a down-conversion mixed-frequency phase-locked loop module, a preset traction module and a control module. The down-conversion mixed-frequency phase-locked loop module adopts a twice down-conversion structure of coarse frequency conversion and fine frequency conversion. Therefore, the down-conversion mixed-frequency phase-locked loop module has the advantages of higher frequency output and lower phase noise, while the size of the down-conversion mixed-frequency phase-locked loop module is kept small. Meanwhile, the preset traction module completes the traction and the coarse tuning of a VCO, so that the wrong locking is avoided. Moreover, the locking speed of the phase-locked loop is remarkably improved, and the agility is realized. According to the technical scheme of the wide-band agile low-phase noise frequency integrated generator, the advantages of low phase noise, small stepping, wide bandwidth and agility are realized.

Description

technical field [0001] The invention belongs to the technology of frequency synthesis generators, in particular to frequency synthesis generators with wide-band agility and low phase noise. Background technique [0002] Radar technology is developing rapidly, and as one of its core technologies, the requirements for frequency synthesis generators are getting higher and higher. With the gradual increase of frequency, low phase noise and spurs have become more and more difficult to achieve, and the structure of the traditional built-in reference crystal oscillator and single phase-locked loop has gradually failed to meet the technical requirements. Due to the characteristics of radar technology itself, in addition to the requirements for low phase noise and low spurs, frequency synthesis generators are often required to achieve wide bandwidth, small steps, high stability, and fast transitions. [0003] In order to achieve small steps and low spurs, an effective way is to use ...

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Problems solved by technology

[0003] In order to achieve small steps and low spurs, an effective way is to use DDS (Direct Digital Synthesizer, Direct Digital Synthesizer) to drive the phase-locked loop; but such a structure is limited by the noise floor of the phase-locked loop itself. It is difficult to achieve low enough phase noise; in addition, with such a structure, the frequency hopping time is still determined by the phase-locked loop, so the frequency hopping speed of DDS cannot be reflected, and fast hopping is still impossible

In order to obtain a sufficiently low phase noise, the general method is to use a high-frequency crystal oscillator as a reference to reduce the frequency multiplication N of the phase-locked loop. However, for crystal oscillators, it is difficult to achieve satisfactory stability at too high a frequency; for To obtain a fast enough jump speed, the general measure is to relax the loop filter, but an overly wide loop filter will lead to insufficient suppression of spurs, and even lead to link instability

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