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LNA Help!!! - RF Cafe Forums

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Post subject: LNA Help!!!

Unread postPosted: Thu Jul 14, 2005 10:27 am



Joined: Mon May 30, 2005 9:16 am

Posts: 1

I'm a gilr who isn't able to design a LNA for ZigBee application at University.The constraints are: Vcc = 1.8V, frequency = 915MHz NF lower as possible,power consumption as well . Could you give me the formulas and one simple (single ended input, differential output) circiut. Please could you give me any suggestions ? I really need it.








Post subject:

Unread postPosted: Thu Jul 14, 2005 10:49 am


Site Admin

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Joined: Mon Jun 27, 2005 2:02 pm

Posts: 373

Location: Germany

Hello Ginevra,

First of all, you will need to select a transistor matching for your frequency band and gain.

There are plenty of formulas to use when you design an LNA: Stability, Gain, Return Loss, Noise Figure etc. Nowadays, Engineers mostly use CAE (Computer Aided Engineering) tools for designing LNA, Filter and other RF circuits. All of these formulas are entered into the design tool and by that save the designer lot of time and calculations.

Attached is a link to a PDF that will certainly give you a good staring point to design your LNA (It includes a discussion about the design and formulas involved in LNA design):

http://www.odyseus.nildram.co.uk/RFMicr ... torial.pdf

Should you need additional help, please let me know.

Good luck!! :wink:


Best regards,

- IR




Post subject:

Unread postPosted: Thu Jul 14, 2005 11:41 am

Dear IR,

Firstly, I have to thank you, I'm reading your link and I think it will be useful.

Secondly, I have to use a CMOS or TSMC 0.18um tecnology, input matching 50 ohm. Do you have any documents about CMOS LNA?

Finally, it is possible to show a circiut in the topic reply without to have a web space?

Thank you again



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