问一个干扰的问题（急）

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我们用的是高通的平台
在Rx中，处于420-460信道的传导灵敏度比其他信道差8dB，这是为什么
先前做过实验，进入Rx芯片的时钟频率TCXO19.2 MHz前加落地电容100pF会改善这种情况，但以前的设计从来没遇到这样的问题。这能完全确认是时钟引起的问题吗？
PCB中时钟信号包地很好
哪位大虾能帮忙分析一下为什么会产生这种问题

看来你的板子存在EMI。我见很多厂家的高通平台的手机，他们都是单独把TCXO屏蔽起来的，不知你是怎么处理的？

注意一下进入主屏的FPC那根时钟线,最好将EMI换换,用RC调试一下!

写错了,刚才说的是无线上的,传导灵敏度你看一下,PM输出的V-RFR是否和PM输出的TCXO-out是否有干扰,我估计主要问题出在V-RFR和TCXO-out以及tcxo中19.2M的输出上,PM输出的TCXO-out并一个50O的电阻看看!我的MSN:dmf1117@hotmail.com

更正：使用39pf会有改善另外，TCXO外加了屏蔽

19.2 MHz的46倍频会落在channel440上,对称的影响420-460 channel SBI_ST控制线加了RC滤波网络没有?
TCXO=19.2MHz; 46th harmonic = 883.2MHz Channel 440 ?
desense in neighboring channels
– Generated unavoidably in TCXO buffer amplifier either external or in the
PM
? Chipx16 clock = 16*1.2288MHz = 19.6608MHz; 45th harmonic =
884.736MHz; Channel 491 ? desense in neighboring channels
– Generated inside the MSM
– Leak out in the digital section such as LCD control lines
? How to confine them?
– Shield both digital and RF sections; separately though
– Layout MSM/memory away from antenna as much as possible
– RC filter all LCD control lines (see example on next page)
– Use a resistor to control TCXO drive level into the buffer amplifier
? General Strategy
– Make sure conductive sensitivity is okay first !
– Try removing LCD completely when re-testing OTA sensitivity
– Measure OTA sensitivity early in the development
– Keep monitoring OTA sensitivity after each board spin
– Does metalized housing help?
– Does EMI gasket/microwave absorber help?