NAND or NOR is faster

[alpeshchokshi]

Nand is much faster than Nor

 

[aslijia]

if you use dynamic circuit, then the nor is faster than nand.

 

[vinod_g]

[ nand is faster than nor in CMOS technology

 

[kazemi]

Because of high electron velocity(mobiliti) and low hole velocity (mobiliti), NMOS is faster than PMOS.
The carriers in NMOS are Electrons and in PMOS are holes.

 

[HenryLai]

CMOS
NAND --> stack NMOS
NOR --> stack PMOS

The NAND is faster than NOR.

 

[ppk_402]

Nand is faster than nor....

 

[bunalmis]

Why PMOS slower than NMOS ?

 

[aslijia]

if there are two transistors, a pMOS and a nMOS, with the same size, then the nMOS can drive twice as much as the pMOS can drive.

 

[salma ali bakr]

Why PMOS slower than NMOS ?

cause considering two transistors with the same W/L ratio, the mobility of the electrons is higher than that of holes, so this leads to higher current for NMOS and thus it's considered faster

for comparing nand and nor, if they have the same electric effort and same number of inputs(same parasitic delay), then since the nand has less logical effort, then the delay in nand is less and thus nand is faster (the logical effort indicates how the topology of the gate affects its ability to output current independent of the external charge (cout) and the transistors sizing (cin))

 

[anmolvlsi13]

Nand is Faster whatever Technology USE?
Because
Pmos w/l is 3 times than NMOS.
So,
risetime is directly prop. to AREA i.e W
Since Wp =3 Wn.
SO, Trp =3 Trn

Anmol

 

[tsavvy]

nand is faster than nor in cmos technology

 

[dsairajkiran]

NAND is faster than NOR gate. The way u r thinking is not correct because at the transistor level NAND gate PMOS transistors are in parallel and there by effective resistance is lesser than the least of their both. And mostly PMOS has more resistance
than NMOS because of the mobility of holes is lesser than electrons. Therefore you are effectively reducing the resistance of PMOS and charging time would be less for NAND than NOR.

More over the symmetry of the signal is maintained both for charging and discharging through PMOS and NMOS.

 

[shachi]

NOR is faser than NAND.
for the following reasons:
1. considering the power dissipation nand dissipates less power than, considering the speed power product. it should be almost constant for a given technology. hence nor is faster.
2. in many text books its given that when the decisions are to be taken in any digital circits or a system NOR is faster than NAND.

 

[yb820903]

NAND is faster than NOR

 

[dsairajkiran]

for nand rise time is less but nor fall time is less.Since in nand pmos are in parallel.both rise time and fall time are symmetric,so nand is better than nor.