VLSI CMOS - Layout to Schematic help!

Hey guys,

I've got my exam for VLSI coming up next week and need some help converting these layouts to schematics. Any ideas how it can be done or where I should look?

Many thanks

 

Hi, you need a "map" to translate it. i.e. look at the attached file

 

thanks for your quick response I haven't been given a map for them, is it possible to guess which pattern is the n-type substrate which is metal 1 ... etc etc from the way it is drawn?

Cheers

 

Yes, you can guess based on how the structures are drawn. The "legs" crossing the substrate are going to be either poly or M1. A poly between two metal legs = a transistor. Typically, for basic diagrams PMOS devices are drawn above NMOS devices (you'll see the two rows of diffusion in each problem). In the circuits without wire labels (VCC/VSS, cat, dog, etc.), start assigning arbitrary labels to keep things straight as you create the schematic. The thick horizontal wires in #2&3 are VCC (top) and VSS (bottom). Be careful though, I'm not sure if your prof wants you to guess at those labels or not.

Note: the first diagram is evidently all NMOS devices...