[phyrrus9]

So, I started talking about IGFETs and CMOS the other day, and just went back to play a little more. Basically there are 4 rules to making a CMOS circuit:

1. Only pull down with n-channel FETs
   
2. Only pull up with p-channel FETs
   
3. Never pull up and down simultaneously
   
4. Always pull the output
   

So, sounds simple enough, right? Yeah, until you try to implement a basic AND gate and realize its not possible. I want you to take a look at this AND2 gate and tell me if it looks familiar to you:


Well it should, because that's not actually an AND gate, it's a NOT NOT AND gate...... For some comparison, here's a NAND (NOT AND) gate:


Still not getting it? I'll put them side by side for you....


And that's why its a fucking pain in the ass.....