The Designer's Guide Community
Forum
Welcome, Guest. Please Login or Register. Please follow the Forum guidelines. Dec 14th, 2017, 8:44am
  HomeHelpSearchLoginRegisterPM to admin  
 
Pages: 1
Send Topic Print
How to find out the BW of a dynamic latch, such as strong arm latch? (Read 114 times)
Frank_Heart
Junior Member
**
Offline



Posts: 29

How to find out the BW of a dynamic latch, such as strong arm latch?
Nov 17th, 2017, 10:22am
 
Hi, Everyone,

  If there is no pre-amp, just a dynamic latch, such as strong arm lath, in the CMP design, how we calculate its BW?

Thanks
Frank
Back to top
 
 
View Profile   IP Logged
DanielLam
Community Member
***
Offline



Posts: 55

Re: How to find out the BW of a dynamic latch, such as strong arm latch?
Reply #1 - Nov 27th, 2017, 7:33pm
 
I usually just sim it with the worst case corner.

Otherwise, this is what I would try.

1) Pick smallest input amplitude
2) Find output time constant (need to spec and output load). The time constant will be gm/Cl or gm/(2*Cl) depending on how you want to calculate the output gms.
3) Find number of time constants needed to amplify input to a "valid" output". For example maybe when the differential output voltage is > 0.6 Vdd.
4) BW =  1/number of tau constants

This would be a rough approximation as the strongarm input transistors go through a saturation to linear mode. For very small inputs, I think you might need to break the amplification time into 2 parts, a linear and a positive feedback portion.

Note: You should just sim it with parasitics. And I've never tried the method I described.
Back to top
 
« Last Edit: Nov 28th, 2017, 9:18am by DanielLam »  
View Profile   IP Logged
Berti-2
Junior Member
**
Offline



Posts: 12

Re: How to find out the BW of a dynamic latch, such as strong arm latch?
Reply #2 - Nov 28th, 2017, 4:30am
 
Why do you want to calculate a bandwidth?
I suggest to just consider and specify the delay of your latch (for the smallest input -> LSB/2).
Back to top
 
 
View Profile   IP Logged
Pages: 1
Send Topic Print
Trouble viewing this site? Copyright © 2002-2014 Designer's Guide Consulting. 'Designer's Guide' is a registered trademark of Designer's Guide LLC. All rights reserved.

Our colleges are not as safe as they seem. Sexual assault is pervasive and the treatment of the victim by the adminstration is often as damaging as the assault: Campus Survivors, Campus Survivors Forum.

Some of our other sites that you might find useful: Avendesora and QuantiPhy.