SPEAKER 1: In the final part of the lecture sequence, I'm
going to show you a fun little demo.
In this demo, I'm going to use an AND gate, like the ones
you've seen before, and apply some inputs to it in a fun
matter, and at the same time, superimpose some noise on one
of the signals.
So for example, what I might do is take a noisy signal,
take some noise, and add that to the y-input.
And if you really believe in all that you've done so far,
then even if noise is added to the signal on y, then the
output of this gate might still be pristine, despite the
noise on the y-input, because this gate is adhering to the
static discipline.
If the gate is correctly interpreting its output low
and output high voltages, then the output must be correct,
even if the inputs are noisy, provided, of course, inputs
adhere to the static discipline.
So let's take a look.
So I'm going to apply a signal x that looks as follows.
And I'm going to apply a signal y that looks a little
bit different, like so.
And so you would expect that the output z is going
to look like this.
So my output is going to be an ANDing of the two inputs.
So not surprisingly, notice that starting at this point,
both x and y are a 1, so z is going to a 1.
And then at this point, x goes to 0, while y stays at 1, so
therefore z pops down to a 0, and then stays at 0 until both
x and y go back up to a 1.
So this is pretty much similar to what we did earlier, and
this is a signal that I expect to see.
Now I want to inject noise into the system.
Then what is going to happen is that the signal y is going
to have some noise superimposed on it.
And what you'll see is that even with the noise
superimposed on the signal, my output is going to stay
pristine because of the static discipline.
Of course, if the noise is so much, so large, that it begins
to overwhelm the gate, the gate is not designed to handle
the noise, then things will go haywire.
But provided the noise is within the noise margin, then
my gate should work correctly.
OK?
Watch and have some fun.