Patent ID: 8583715

Claim:
A method of programmably configuring a programmable integrated circuit device as a CIC filter structure, said method comprising: accepting input, into a software tool for configuring said programmable integrated circuit device as said CIC filter structure, of particular values of CIC filter parameters N, R, M, B in and B out , where N is number of interpolation/decimation pairs or stages, R is interpolation/decimation rate, M is differential delay, B in is input bit width and B out is output bit width; recalling variance error gain terms F j , corresponding to said particular values of CIC filter parameters N, R, and M, from among possible F j terms that were previously calculated for various values of N, R, and M, and were stored in association with said software tool, said particular values being among said various values; and from said recalled variance error gain terms F j and said B in and B out terms, calculating for each stage j a bit width term, B j , for Hogenauer pruning for a CIC filter; wherein: said software tool is created by: defining a respective range, for said various values of each of said CIC filter parameters N, R, and M, supported by said tool, pre-calculating possible variance error gain terms F j for Hogenauer pruning for said various values in said respective ranges of CIC filter parameters N, R, M, and storing said pre-calculated possible variance error gain terms F j for Hogenauer pruning in association with said software tool.