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[Help] How to connect PA with LNA to share the same antenna!

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guilinwxb

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Hi, everyone. I am design a 2.4GHz CMOS transceiver IC. But I don't know how to connect PA with LNA to share the same antenna, and has TX/RX switch. The PA core and LNA core are depicted as the figure below. Anybody can help me? Thanks!
guilinwxb


 
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vfone

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Re: [Help] How to connect PA with LNA to share the same ante

You need a balun on each side (RX and TX), and the outputs of the baluns routed to the SPDT T/R switch.
 

kspalla

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use two spdt switches.
let say +ant, -ant is the common signal on state 1of swich it connects +ant to +PA and -ant to -PA on the switch toggle +ant to +LNA and -ANt to -LNA
You need tWO SPDT switches to have the required isolation.

Added after 36 seconds:

I mean DPDT should be OK
 

DDavid

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Re: [Help] How to connect PA with LNA to share the same ante

Hi

You can design the switch with 2 diodes!!
of course you must consider the isolation.

Also you can use with cilculator and isolator!!!

David
 

guilinwxb

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Re: [Help] How to connect PA with LNA to share the same ante

Thans everybody, after reference some IEEE paper, I decide to use this switch such as below and use a match network off chip. Tune the LC network to let the LNA's noise as low as possable and the output power of the PA is as large as possable. But I feel it's difficult to tune. Do you have any suggestion?

Thanks
guilinwxb
 
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