一种超宽带超低相位噪声频率综合器

为了解决直接频率合成方法频带拓展困难和锁相频率合成方法相位噪声附加恶化严重的问题，设计了一种联合直接模拟频率合成和锁相频率合成的混频锁相频率综合器. 该频率综合器采用梳谱发生器激励超低相位噪声的偏移信号后，再将该信号插入锁相环进行环内混频，降低鉴相器的倍频次数进而优化输出信号的相位噪声，同时解决了超宽带混频锁相环的错锁问题. 该文设计的频率覆盖范围为12~24 GHz、步进为100 MHz的超宽带频率综合器实验测试表明:频率综合器在低频段12 GHz处相位噪声优于?116 dBc/Hz@1 kHz，在高频段24 GHz处相位噪声优于?109 dBc/Hz@1 kHz，相位噪声指标与直接模拟频率合成方法相当，均优于传统锁相方法20 dB以上. 本文混合频率合成方法具有超宽带和超低相位噪声的优点，可以用于高性能的电子设备和系统.

An ultra-wideband ultra-low phase noise frequency synthesizer

In order to solve the problems of frequency band expansion in direct frequency synthesis method and serious additional deterioration of phase noise in phase-locked frequency synthesis method, a mixer phase-locked frequency synthesizer combining direct analog frequency synthesis and phase-locked frequency synthesis is designed. In order to reduce the frequency multiplication times of the phase detector and optimize the phase noise of the output signal, the frequency synthesizer uses a comb spectrum generator to excite an offset signal with ultra-low phase noise for mixing. In the meantime, the error-lock problem is solved in ultra-wideband mixing phase-locked loop (PLL). An ultra-wideband frequency synthesizer with frequency band 12 GHz–24 GHz and step of 100 MHz is designed in this paper. The experimental test of the frequency synthesizer shows that the phase noise of the frequency synthesizer is better than -116 dBc/Hz@1 kHz at low frequency 12 GHz, and ?109 dBc/Hz@1 kHz at high frequency 24 GHz. This phase noise is basically the same as the direct analog frequency synthesis method and is 20 dB better than the conventional phase-locked scheme. The frequency synthesis method has the advantages of ultra-wideband and ultra-low phase noise, and it can be used in the high performance electronic equipment.