The Designer's Guide Community Forum https://designers-guide.org/forum/YaBB.pl Design >> Mixed-Signal Design >> How to find out the BW of a dynamic latch, such as strong arm latch? https://designers-guide.org/forum/YaBB.pl?num=1510942971 Message started by Frank_Heart on Nov 17th, 2017, 10:22am

 Title: How to find out the BW of a dynamic latch, such as strong arm latch? Post by Frank_Heart on 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?ThanksFrank

 Title: Re: How to find out the BW of a dynamic latch, such as strong arm latch? Post by DanielLam on 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 amplitude2) 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 constantsThis 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.

 Title: Re: How to find out the BW of a dynamic latch, such as strong arm latch? Post by Berti-2 on 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).