请问滤波器的问题

我需要测试一个TCXO输出时钟的phase noise，16MHz，但是TCXO的输出是方波，测试仪需要输入是正弦波，故需要搭一个大概20M－30MHz的滤波器。请问哪位大侠给点建议，LC的好还是RC的好?对phase noise的测试结果有多大的影响?Thanks！

个人觉得用LC滤波较好，RC滤波会使相位延迟45度（-3db)。不知道对不对，请大家指教。

个人觉得LC好,都有相位延迟,但LC无损耗.可做个LADDER带通.

合乎
很不错了！

I don't know why you need a filer.
A square wave could be tested in spectrum just ignore the harmonic terms.
If you use the oscilloscope, you need the very long sample sizes for FFT.
Or in time domain, you can show the eye diagram for jitter.