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network matching for RF module FXTH87

Question asked by sunrme on Nov 23, 2015
Latest reply on Jun 30, 2017 by David Ramirez

Hello,

I’m working with FXTH871511 and now I'm testing RF module. So I have a problem, because it works not so well like others analogs.

I’m not a professional in RF and don’t know much in this orea, so if any of my thoughts are not right please correct me.

So, I found two solutions for network matching in documents.

     1)      From KIT. This scheme for 434 MHz (from here) :

1.png

I remove extra components like DNP or 0 Ohm, and get scheme like on right side. In this case RF module work but I think only for 30% of opportunities (I check the distance from transmitter and receiver).

     2)      Second scheme I also get from the same file:

RF transmitting does not work. Because need to pull up L2 to VDD (like in datasheet)

Also need add capacitance between RF and GND (FXTH87EDRM: a parasitic capacitance of 3 pF is added between the RF out and ground to reach the device output impedance.)

So we get scheme like this:

Now, the transmitter works but I think for 70% of max optimal values.

 

So, please help me to choose right solution and how I can improve it to get better work for RF module.

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