Tutorial #6

6-0: Basis schematic: Creation of a ‘sized pair’ file for efficient construction of CMOS circuits

Create a schematic file that contains one each of an nMOS and a pMOS transistor, as shown

Parameterize these transistors so that sizes can be uniformly affixed and manipulated by the pSPICE parametric option. In this case we assume that the source/drains for each transistor extend out from the transistor by 2mm.

As indicated, we have identified the lengths of the transistors to be the same = {Lx}. Widths are {Wn} for the nMOS and {Wp} for the pMOS transistors.

Now create declaration tables (PARAM part) that ensure that these parameters are accessible in the most likely form for circuit scaling and assessment..

Save the file as ‘sizedpair’ (or some other), with the idea in mind that this file and pair of transistors will serve as a start pair that can be copied and pasted into a new schematic screen, and therefore become a basis file for use as a starting point for any analog circuit configuration that we may desire to test.