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What will happen if we swap the transistors of an inverter?

Posted: Wed Apr 09, 2014 3:46 pm
by Arvind
What will happen if we swap the transistors of an inverter?

Re: What will happen if we swap the transistors of an invert

Posted: Wed Apr 09, 2014 3:51 pm
by Narveer
If we swap the transistors of an inverter that means NMOS will acts as pull-up transistor and PMOS acts as pull-down. So

1. when input is HIGH then PMOS is in cut-off region and NMOS pull-up output to HIGH state. But output voltage will Vtn( i.e threshold voltage for NMOS) less than VDD. NMOS is BAD-1 switch.
2. When input is LOW then NMOS is in cut-off region and PMOS pull-down output to LOW state. But output voltage will Vtp( i.e. threshold voltage for PMOS) high than VSS. PMOS is BAD-0 switch.

So we have less output voltage swing and less noise margins.

Nmh(Noise margin in HIGH state)= Voh-Vih
Mml(Noise margin in LOW state)= Vil-Vol

Voh= Maximum output voltage available in high state
Vih= Minimum input that can be considered as high
Vil= Maximum input voltage that can be considered as low
Vol= Minimum output voltage available in low state

Re: What will happen if we swap the transistors of an invert

Posted: Tue Apr 15, 2014 12:36 pm
by nikhilp
A BAD BUFFER...thats all!