Powerful simulation programs for circuit simulation and IC simulation can be used today to simulate IC circuits to the nth degree. However when the initial design is done it is usually done using some identities for the various DC and AC parameters of the MOSFET. This allows fast hand calculations and possibly a sanity check of the results obtained from the more complex models built into the simulator. A set of these identities can be found on the SPG website under engineer’s corner. Interested readers can access these at http://www.signalpro.biz > engineer’s corner.