Which one is better for designing circuits, NAND or NOR ?

[rogger123]

NAND or NOR

hi,
when designing circuits which one is preferred NAND or is the NOR gate preferred. any particular reasons.
Whihc would occupy more area NAND or NOR?

Rogger

 

[starfish]

Re: NAND or NOR

NAND gate is preffered...............

NAND is a universal gate and u can form any gate using NAND gate......i:e AND , OR , INVERTER etc call all be formed by using NAND gate.............

 

[rogger123]

Re: NAND or NOR

NOR is also an universal gate all gates can be implemented using NOR gate ..
Question is which one is preferred

 

[manitooo]

NAND or NOR

Well...; it depends the way you want to use this memories...

in a simple way, NOR is a good choice for program memories

NAND is a good way for data memories...


NOR : random read, page read or burst read, but it is more difficult to write (you have to respect a spécial protocol.... and you also need to erase the entire page before write in it..

good for instructions fetching because of the read access... when jumping to an instruction, just change the adress and it's ok

NAND : page managing mempories with buffer... you work with buffers (like cache memories) and manipulate them... good choice to put and read big chunk of data (images, video, songs and so on...) but because of its pages access, it's difficult to use it as a program memories because of jump.... when jumping to a new instruction, you can point to an another page which involved the complete reloading of the new page, while discarding the old one and that takes a lot of time in terms of instruction processing...


nevertheless, you can use RAM cache memories like RAM, PSRAM or SDRAM to prefetch a chunk of program...


BTW, in terms of cost, NAND is cheaper than NOR... but NOR is more reliable than NOR in terms data reliablity retention... it is why NAND users often use algorythm for error detection..

bye

 

[s0shinde]

Re: NAND or NOR

Depends on which technology is used. In CMOS NAND is preffered for designing. Mobility of electrons is more than holes. In NOR gates the two PMOS gates are in serial while in NAND the two PMOS gates are in parallel.

 

[chaitu2k]

Re: NAND or NOR

well in terms of area nand would be preffered because of the logical effort involved in nand is 4/3 compared to 5/3 in nor.....this is given in digital circuit design by rabey...refer it...

 

[konqueror]

Re: NAND or NOR

if u are using complementry mos than nand will be preferred due
to area considerations.
but if u are using dynamic logic nor gate will be preferred as it
constitutes lesser delay during evaluation cycle.as in nand the
n-transistors are in series & delay increase quadratically as the
no. of transistors

 

[carrot]

Re: NAND or NOR

hi

NAND gate is preferred than NOR GATES.

Y=Abar.bbar
Y=Abar+Bbar

In NAND gate if u observe nmos is in series and pmos is in parallel. So the mobility of electrons is higher since nmos is higher.

In NOR gate if u observe nmos is in parallel and pmos is in series. So the mobility of electrons will be distributed.

In terms of Area NAND is preferred

 

[chandreou]

NAND or NOR

nand because of effort

 

[gevy]

Re: NAND or NOR

In CMOS NAND gates are more preferable, as have the smaller area.
It is determined by a choice of a threshold of gate equal to half of supply voltage. In this case NAND gate has the sizes of transistors are close, and NOR gate has the sizes of transistors differ more and therefore the area more.

 

[spauls]

Re: NAND or NOR

NAND gate has Less Propagation delay as compared to NOR , so NAND is preferred.

 

[DrDolittle]

Re: NAND or NOR

NAND gate is most commonly and wodely used logic.Even in supercomputing architecture multiplexers and all adder units uses NAND logic prevelantly.

regards
drdolittle

 

[maharshi_qis]

Re: NAND or NOR

for low power dissipation we design with NAND logic..
if u need ur ckt to be faster,u ll go for NOR logic..

 

[sivakumar_tumma]

Re: NAND or NOR

hi,
when designing circuits which one is preferred NAND or is the NOR gate preferred. any particular reasons.
Whihc would occupy more area NAND or NOR?

Rogger

NAND gate is prfrerred over NOR gate. Y I dont remember eactly...........

It is due to 1. Logical effort ==>realetd to delays in bothe paths
2. symmetry of construction

Both are applied to CMOS technology........

 

[nguyennam]

Re: NAND or NOR

NAND is much easier to find out in the market than NOR, and cheaper.

However, there is the case when you have to use NOR, cannot replace by the circuit with NAND.

nguyennam

 

[tronix]

Re: NAND or NOR

Hey Rogger123

You can have a look at this


The choice depends on logic used eg in CMOS Logic Nand is preferred as it ocuppies less space and NOR is used in pseudo-logic again for same reason (you can refer to CMOS Logic text in Sedra Smith for explanation).

Regards
tronix

 

[raghu_836]

Re: NAND or NOR

As per the timing analysis the nand gate is worst i think
but nor gate is fast

 

[ffrontech]

Re: NAND or NOR

NAND gate is preffered...............

NAND is a universal gate and u can form any gate using NAND gate......i:e AND , OR , INVERTER etc call all be formed by using NAND gate.............

even nor is a universal gate