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How NMOS must b connected?

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jeet_asic

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Is it mandatory tht we should connect source of nmos to ground ? can't drain of nmos b grounded? ... pls tell reason behind connections. :grin:
 

recall that 'source' is supplying carriers.
for n channel mos , source should supply electrons.

if source at ground and drain towards more +ve voltage , the gate has c ontrol on on-off of the mosfet.
but an isolated nmos with symmetry in making , source and drain are for our reference only.
 

In my understanding, the purpose of having source and drain is to get a good ohmic contact. Electrons that flows through the channel are provided by power supply not source. In symmetrical MOSFET, both source and drain are same. This naming convection is used for our understanding. The terminal at lower potential is treated as source and terminal at higher potential is called drain.
 
If specifically, NMOS terminals are not denoted by source or drain ( as DEMOS devices), source and drain are symmetric and can be interchanged. There is no difference in the functionality. Terminal with less potential will tern into source and higher potential in to Drain. During functionality itself, they can change their role.
 

Ok , so it means that we differentiate pins for our understanding , unless it is symmetric , Drain n source pins can b interchanged. Though i am little confused . Why terminal at lower potential is treated as source . As "Source" name suggests , it should b connected to higher potential (Vdd) n drain to ground? Doesn't "drain" mean that charge (taking capacitor as load) inside capacitor will drain out when NMOS is applied high input i.e. 1 ... pls Correct me .
yadavvlsi said:
In my understanding, the purpose of having source and drain is to get a good ohmic contact. Electrons that flows through the channel are provided by power supply not source. In symmetrical MOSFET, both source and drain are same. This naming convection is used for our understanding. The terminal at lower potential is treated as source and terminal at higher potential is called drain.
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Yes, Source and drain can be interchanged. The terminal at lower potential is considered as source while terminal at higher potential is called drain.
The Conventional current is defined to flow in the same direction as positive charges while electronic current is same as direction of flow of electrons. In case of MOSFET electrons flows from source to drain which are provided by power supply. If you see MOSFET only, it seems electrons are coming from source and collected at drain.
 
If you see MOSFET only, it seems electrons are coming from source and collected at drain.
Click to expand...
In case of NMOS yes, source provides the electrons, but what about PMOS case, are you telling here source again provides electrons.
I understand , MOSFET is uni carrier devices, current flows by either holes or by electrons. NMOS case source provides electrons, PMOS case , source provides holes.
 

How can a source provide only electrons or hole when connected to nmos or pmos? does it mean that PMOS holes attract electrons from VDD and NMOS electrons attract holes from ground.
varunkant2k said:
In case of NMOS yes, source provides the electrons, but what about PMOS case, are you telling here source again provides electrons.
I understand , MOSFET is uni carrier devices, current flows by either holes or by electrons. NMOS case source provides electrons, PMOS case , source provides holes.
Click to expand...
 

The source is so named because it is the source of the charge carriers (electrons for n-channel, holes for p-channel) that flow through the channel; similarly, the drain is where the charge carriers leave the channel.

---------- Post added at 11:29 ---------- Previous post was at 11:28 ----------

MOSFET - Wikipedia, the free encyclopedia
 
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