00:01
Alright, so we'd like to find the amplifier gain here, which is the output voltage divided by the input voltage.
00:09
Sorry, that's our o -i -m -i in green.
00:13
Output voltage, v -o, divided by input voltage v -s, which is v -o over 250 millivolts.
00:23
Let's see what exactly is v -o.
00:27
Well, what i can see happening here, i'm going to just arbitrarily assign this guy to ground.
00:37
This is 250 millivolts.
00:42
Mills typically means milliamps.
00:44
This here is 4 times 10 to the 5 times i -b.
00:53
What is i -b? what i see is that this voltage here is going to be i -b times 500 ohms, whatever that is.
01:06
Which means this is also i -b times 500 ohms, and our current down through here will be v divided by r.
01:13
So i -b times 500 ohms divided by 5 kilohms, 5 ,000 ohms, which is 0 .1 times i -b.
01:28
0 .1 times i -b.
01:33
Now, 0 .1 i -b coming out through there.
01:36
I -b, of course, is coming out through there.
01:39
So the voltage through this whole thing must then be equal to, the current through that thing must be 1 .1 times i -b.
01:49
And that is equal to the voltage divided by the resistance, right? so that's the voltage, 250 millivolts, divided by the resistance, 100 ohms...