The Designer's Guide Community
Forum
Welcome, Guest. Please Login or Register. Please follow the Forum guidelines.
Oct 21st, 2020, 12:18pm
Pages: 1
Send Topic Print
Max power gain for LNA (Read 3323 times)
N Logan
Guest




Max power gain for LNA
Feb 03rd, 2004, 2:19pm
 
If I designed an LNA with the input stage being a classical common source type (N-type) and then using a P-type as a unity gain current buffer.

Now I am not quite sure how or what would be wrong, but if the 1st stage had an excellent voltage gain (i.e. biased to have such a low current since current inversely proportional to Av.

And then for the 2nd stage I biased the P-type current buffer with a larger current.

Now why will this not provide the best power gain? Or will it? thanks
Back to top
 
 
  IP Logged
jdeng
New Member
*
Offline



Posts: 1

Re: Max power gain for LNA
Reply #1 - Feb 12th, 2004, 4:22pm
 
I'm not sure whether you have considered the effect of mismatch between first stage and buffer.
Back to top
 
 
View Profile   IP Logged
n.logan
Guest




Re: Max power gain for LNA
Reply #2 - May 8th, 2004, 1:45pm
 
Can I put it another way.- If I terminate the output to a large impedence I have a great voltage gain. If I matched it to 50 ohms I don't. How will I buffer the output so that I don't lose gain Av=GmRo

Thanks
Back to top
 
 
  IP Logged
kokabanga
Junior Member
**
Offline



Posts: 28

Re: Max power gain for LNA
Reply #3 - May 20th, 2004, 3:48am
 
the 1st stage will see a load cap in the gate of the second stage. you need to cleverly tune out this capacitance int he gate of ur second stage CD buffer. and then match the CD buffer to a 50Ohm.

I am doing same thing here and it works
Back to top
 
 

naren
View Profile   IP Logged
Pages: 1
Send Topic Print
Copyright 2002-2020 Designer’s Guide Consulting, Inc. Designer’s Guide® is a registered trademark of Designer’s Guide Consulting, Inc. All rights reserved. Send comments or questions to editor@designers-guide.org. Consider submitting a paper or model.