Designer’s Guide Community

New Member

Offline

Posts: 6
Bangalore

mismatch analysis
May 01^st, 2007, 11:57pm

Hi all,

Am trying to find mismatch in current mirrors through DC analysis. I try to measure the current output by varying the three parameters w, l and vtho of the key transistorsm in the current mirror. I am able to sweep the two component parametrs w and l. Since vtho is a model parameter am not able to introduce mismatch to it.

Is there any way to declare it as a variable so that i can use it as another sweep parameter? Is it like the pdk should support the variations of the vtho? any suggestions??????

Am using spectre simulator.

Thanks in advance.

PS: No model files available to run monte Carlo or dcmatch analysis.

Back to top

IP Logged

ACWWong Community Fellow Offline Posts: 539 Oxford, UK	Re: mismatch analysis Reply #1 - May 2^nd, 2007, 8:04am A simple (but crude) method would be to introduce a voltage source in the gate of the transistor to sweep the impact of vgs mismatch, which is correlated to threshold mismatch.
Back to top	IP Logged

John O Donovan Junior Member Offline Posts: 29 San Jose, CA	Re: mismatch analysis Reply #2 - May 2^nd, 2007, 9:34am Hi, If you are using BSIM4 or BSIM3v3 models, then there are instance parameters for doing this in Spectre. You can use delvto shift in zer0-bias threshold voltage vth0. delk1 shift in body bias coefficient k1. delnfct shift in subthreshold swing factor nfactor. You can find descriptions in 'spectre -h' Regards, John
Back to top	IP Logged

Andrew Beckett

Senior Fellow

Offline

Life, don't talk to
me about Life...

Posts: 1742
Bracknell, UK

Re: mismatch analysis
Reply #3 - May 8^th, 2007, 1:41pm

There's also spectre's dcmatch analysis (see spectre -h dcmatch for more details). There are parameters in bsim4 and bsim3v3 (and some other models too), for example:

Code:

DC-mismatch dependent parameters:
816     mvtwl=0.0 V*m     Threshold mismatch area dependence.
817     mvtwl2=0.0 V*m^1.5
				  Threshold mismatch area square dependence.
818     mvt0=0.0 V	  Threshold mismatch intercept.
819     mbewl=0.0 m	 Beta mismatch area dependence.
820     mbe0=0.0	    Beta mismatch intercept.

Regards,

Andrew.

Back to top

IP Logged