Question about driving capability of nmos and pmos

Status
Not open for further replies.
I

icx

Junior Member level 2
Joined
Mar 12, 2006
Messages
21
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Activity points
1,447
About driving capability

in one inverter,nmos size is wn/ln and pmos size is wp/lp. In order to
design one 2 input nand gate with same driving capability as inverter,what
is the size of nmos and pmos in nand gate?

a.nmos=wn/ln,pmos=wp/lp
b. nmos=2wn/ln,pmos=wp/lp
c. nmos=wn/ln,pmos=2wp/lp
d. nmos=2wn/ln,pmos=2wp/lp
 

Re: About driving capability

hear you are what i think... since a NAND gate involves two series NMOS transistors and two parallel PMOS transistors, and since you need the overall PMOS to NMOS aspect ratios to be about 2 (actually, it is 2.4), you'll need to have Wn/Ln=2 (the overall Wn/Ln now is 1)and Wp/Lp=1 (the overall Wp/Lp now is 2)...

hope this helped...
 

Re: About driving capability

for this OVT's interview test,

2 is correct. but actually the ratio depends on process. normally 3times.
 

About driving capability

i think in the p-network we take worst case senario (i.e. only one of the mos is working) so the wp/lp=2
so i think d is correct
 

Re: About driving capability

safwatonline said:
i think in the p-network we take worst case senario (i.e. only one of the mos is working) so the wp/lp=2
so i think d is correct
Click to expand...

that's right... i have mistaken.... safwatonline is correct
 

Status
Not open for further replies.

Similar threads

Menu
Log in
Register
Cookies are required to use this site. You must accept them to continue using the site. Learn more…