S-band Broadband Frequency Agile Frequency Source Research

Broadband, low spurious and agile frequency-hopping are the key technology for electronic and electrical systems. The agile frequency-hopping synthesizer is widely used in systems of radar and spread spectrum communication, not only does it be able to resist the interference, but also largely improve the processing capability, which presently is the hot research focus among designers of electronic and electrical systems. Currently, super high speed frequency-hopping communication and radars are lack of comprehensive development, the reason for which is that performance of the frequency-hopping synthesizer cannot reach the standards. Thus, further explorations on broadband, fast frequency-hopping have significantly practical valuables to enhance the performances of electronic countermeasure, radar, guidance and control, remote sensing and testing, as well as millimeter-wave communication.In this paper, on the basis of theories of frequency synthesizer, several frequency-hopping proposals are discussed and compared. In order to satisfy different needs of customers, different frequency-hopping synthesizers are adopted. Generally, three different frequency-hopping synthesizers are explored, which adopts phase-locked loop(PLL), direct digital synthesizer combined with FPGA respectively to exert their own advantages, further to overcome each proposal's deficiency.During the research process, based on PLL technology with DDS in loop band, the frequency-hopping synthesizer adopts dual loop with DDS, which realizes that the frequency-hopping time reaches nearly 9us when the frequency step is less than 100MHz frequency step in the band from 2710MHz to 3210MHz. Moreover, based on DDS technology with higher speed frequency-hopping, such frequency synthesizer can realize frequency-hopping time less than 4us with any frequency step; Lastly, based on the technology of DDS,FPGA and PLL with external mixer, the synthesizer can be able to realize frequency-hopping time less than 1.5us with any frequency step. All three proposals mentioned above not only simultaneously solve the problems with different frequency-hopping times, but also have good spurious compression better than 60dBc and great phase noise better than -97dBc/Hz@1KHz. Therefore, the goal of this project is perfectly accomplished.