New optimising feature in SPICE

The field of optimisation is still not appropriately covered in modern computer programs for circuit analysis as SPICE, which was originally developed at the University of California at Berkeley. The last official release of SPICE was published in 1992 and includes interactive interpreter language called Nutmeg, which is at first glance very convenient for coding optimisation loops. But it turns out that Nutmeg has numerous of bugs and is therefore unsuitable for optimising larger circuits with more parameters. Because of that reason the original code was modified. The majority of bugs were found and fixed. The code was also modified in order to run under Windows 95/98/NT. New compilation of SPICE, which offers a native SPICE environment on PC and allows longer coding (for example optimisation method) in Nutmeg, is introduced in this paper. Further, Nutmeg shows as to slow because of its interpreter nature. To overcome this problem in optimisation loops, a new command for circuit optimisation was added. In the paper, coding of optimisation loop in Nutmeg and the new optimize command are presented through two cases. All simulation files as well as the new compilation of SPICE may be downloaded from http://fides.fe.unilj.si/spice/.