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PA - RF Cafe Forums

Because of the high maintenance needed to monitor and filter spammers from the RF Cafe Forums, I decided that it would be best to just archive the pages to make all the good information posted in the past available for review. It is unfortunate that the scumbags of the world ruin an otherwise useful venue for people wanting to exchanged useful ideas and views. It seems that the more formal social media like Facebook pretty much dominate this kind of venue anymore anyway, so if you would like to post something on RF Cafe's Facebook page, please do.

To the left are all of the forum threads, including all the responses to the original posts.







Post subject: PA Posted: Fri Jun 17, 2005 7:50 am
am new in microwave power amplifiers.
I can build the system using couple of tranistors , capacity and inductors .
the probleme is how we can find the transistor model that we need to use .
and how we can find the system layout using ADS
please answer at


Post subject: Posted: Sun Jun 19, 2005 9:07 pm


Joined: Tue Mar 15, 2005 11:43 pm
Posts: 65
Location: Singapore

For choosing transistors for RF PA, you need to consider the specifications of the PA, such as how much gain are you needed, how much power and linearity to be achieved. and whether it's single-stage or multi-stages PA?

For example, at multi-stages PA, usually we use high-impedance transistor at first stage and low impedance transistor at last stage. The high impedance gives us lower input reflection with simpler input and interstage matching networks .

While the high impedance at the last stage (output side) will give us some room for power matching at the end.

and also , you may consider the gain you need, and check the GMax of the transistors, and see whether it is possible to achive certain gain.

If you could provide me more details, I might be able to help you.

Hope it helps,



Post subject: PAPosted: Wed Aug 10, 2005 3:54 pm
thanks alot for answering my request .and sory for not responding earlier n that time
in fact my problem is when designing the PA , i needed to choose a model for my FET transistors (am using ADS software), and i don't have do u need any place were i can telecharge the library that i will need .

thanks alot for all


Post subject: Posted: Thu Aug 11, 2005 7:31 pm
You can visit some transistor supplier for more infor: advanced power technologies RF, macom or philip...

You can find more info by talking to their application engineers....good luck to you

Posted  11/12/2012