The Designer's Guide Community
Forum
Welcome, Guest. Please Login or Register. Please follow the Forum guidelines.
Oct 31st, 2024, 4:51pm
Pages: 1
Send Topic Print
IP3 in mixers (Read 4377 times)
Superowl
New Member
*
Offline



Posts: 1

IP3 in mixers
Feb 25th, 2005, 2:13am
 
I've been noticing that single-balanced MOS mixers have slightly better IP3 than double-balanced MOS mixers. Anyone have enlightenment as to why that's so?
Back to top
 
 
View Profile   IP Logged
nano_RF
Community Member
***
Offline



Posts: 50
madison
Re: IP3 in mixers
Reply #1 - May 10th, 2005, 11:43am
 
As for as I know the IIP3 of the mixer or measure of linerity depends on the gate overdrive of the rf input. The higher the overdrive(Vgs-Vt) the better the IIP3 would be.

In single balanced case u might be using a transconductor as a V-I converter,wheras in double balanced case usualy a tail current source is also used for current matching purposes in left and right side branch. or to say to keep the IF amplitude constant. In that case the allowable overdrive of the RF input must have been reduced. And that could be reason for a lower IIP3. In my view if a tail current source is not used than one can expect the same IIP3 in both cases.

I am a self learner of RFIC design, so may be my analysis is fundamentally wrong. But i wish if somebody can correct me if I am wrong.

Thanks,
--Vikas
Back to top
 
 
View Profile   IP Logged
J
Guest




Re: IP3 in mixers
Reply #2 - May 10th, 2005, 12:17pm
 
are you assuming the RF goes into the transconductance stage and the LO goes into the switching stage? cuz that's what I was assuming.
Back to top
 
 
  IP Logged
nano_RF
Community Member
***
Offline



Posts: 50
madison
Re: IP3 in mixers
Reply #3 - May 10th, 2005, 12:39pm
 
yes I am assuming that RF is fed in to V-I converter and LO to switching .
Back to top
 
 
View Profile   IP Logged
J
Guest




Re: IP3 in mixers
Reply #4 - May 10th, 2005, 3:29pm
 
The higher the overdrive(Vgs-Vt) the better the IIP3 would be .. can you refer to me a source that talks about this?

How would you determine the overdrive of current source, and why does a transistor have more overdrive than a current source?
Back to top
 
 
  IP Logged
Pages: 1
Send Topic Print
Copyright 2002-2024 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.