一种低杂散低相噪频率源的设计与实现

Design and implementation of a low phase noise frequency synthesizer

为了降低频率综合器的相噪和复杂度,提出了一种新的低相噪频率综合器的设计方法。它利用谐波发生器产生低相噪的高频信号,同时采用集成压控振荡器的频率合成器芯片LMX2820来直接产生输出信号和反馈信号,反馈信号和低相噪高频混频后产生低频的反馈信号,通过这种内置混频来降低分频值的方式来实现低相噪。采用该方法实现的13.75 GHz~16.25 GHz(不包含15 GHz)频率合成器,其相噪指标优于-102 dBc/Hz@1kHz。

In order to reduce the phase noise and complexity of the frequency synthesizer,a new design method of low phase noise frequency synthesizer is proposed in this paper.It uses the harmonic generator to generate the high-frequency signal with low phase noise.At the same time,the frequency synthesizer chip LMX2820 integrating the voltage controlled oscillator is used to directly generate the output signal and feedback signal.The feedback signal and low-phase noise high-frequency mixing generate the low-frequency feedback signal,Low phase noise is achieved by reducing the frequency division value through this built-in mixer.The phase noise index of the frequency source of 13.75 GHz~16.25 GHz(excluding 15 GHz)is better than-102 dBc/Hz@1kHz.