fanfelle@iris.ucdavis.EDU (Rob Fanfelle) (11/14/90)
Hello all, (sorry for the length) I am hoping that I could get some feedback on people's experiences with (digital) circuit simulators. At the moment I am using IRSIM v8.6 (included in V6 of Magic) to simulate the functionality and general timing characteristics of my single- chip processor. IRSIM models each transistor as a resistor in series with a voltage controlled switch. No resistance is used from the extracted layout, but each node does have a lumped capacitance derived from the layout. I also have access to NYU's Crystal (enhanced by Richard Kenner for CMOS), although I do not yet have it up and running. Does anyone know how IRSIM stacks up against Crystal as far as the accuracy of timing [Assuming a relatively well behaved layout; fairly standard CMOS with some transmission gates and a few NMOS techniques employed (ex. pmos pull-ups)] Does Crystal have advantages/strengths over IRSIM? I have considered simulating "non-standard CMOS" cells with SPICE and then using a form of backannotation for IRSIM (use the netchange command). Has anyone tried this? Did you find that the increase in accuracy was worth the trouble? Are there other INexpensive simulators that are fast and that (fairly 10-15%) accurately model the timing of high-speed VLSI designs? Any indication as to how they compare to other simulators or actual tested chips? Either general or specific information would probably assist me in making my decision for which simulator to use. Right now I intend to use IRSIM for general design characterization and then switch to SOMETHING else for the accurate timing and fine tuning of the design. I apologize if it seems I am asking a lot but I would just like to get a feel for what tools are avaiable and how accurately I should expect them to perform. (especially IRSIM) I will gladly post a summary of information that I obtain so that others can benifit. (I've already been contacted by a few interested people) Thanks for your time!! Rob login: fanfelle Inet: iris.ucdavis.edu (128.120.57.20)