Static voltage transfer characteristics

[Shackman]

I know how to find the static voltage transfer characteristics (output low voltage, input low voltage etc) for one input gates like an inverter from the graph of Vout v Vin.
My question is how do I apply this to gates with two inputs? These graphs have two curves by keeping one input constant and the fluctuating the other, and then vice versa.
Would the worst-case low noise margin become the smaller input low voltage minus the larger out low voltage and the worst-case large noise margin become the smaller output high margin minus the smaller input high margin?
Or would I find the noise margins as I would for one curve, and taking the smaller of the two?

 

[berkeman]

I know how to find the static voltage transfer characteristics (output low voltage, input low voltage etc) for one input gates like an inverter from the graph of Vout v Vin.
My question is how do I apply this to gates with two inputs? These graphs have two curves by keeping one input constant and the fluctuating the other, and then vice versa.
Would the worst-case low noise margin become the smaller input low voltage minus the larger out low voltage and the worst-case large noise margin become the smaller output high margin minus the smaller input high margin?
Or would I find the noise margins as I would for one curve, and taking the smaller of the two?

I'm not understanding the question very well, but in general there is no interaction between multiple inputs on a gate.

 

[Shackman]

I was tasked with finding the worst case noise margins from two input characteristic curves and I think that in most practical cases it is the same as finding the noise margins for one curve. I thought that the noise margins may be measured as a combination of the two curves doesn't seem likely. I wasn't sure and I had a homework assigned with that question so I wanted to make sure, but I will check back once it is graded to make sure!