OTA-C BIQUAD-BASED FILTER SILICON COMPILER

An integrated software system that facilitates the design, and integra ted-circuit layout of continuous-time OTA-C filter biaquad-based struc tures with typical cutoff frequenceis for a 3 mum technology in the 50 0 kHz-8 MHz range is described. The proposed integrated software syste m consists of three separate software modules written in the C languag e for the Apollo workstation (DN3000). The first module is a general f ilter approximation package. This program can approximate conventional magnitude, arbitrary magnitude, arbitrary group delay equalizer, arbi trary magnitude with group delay specifications. The second module aid es in the synthesis of the biquad-based OTA-C filter structures. This module is unique in that the C code has the rule-based language CLIPS embedded within the code, and takes into account OTA-C filter nonideal ities. An expert system using CLIPS was developed to select an appropr iate OTA-C filter structure based on the nonidealities of the structur es. After the filter structure has been chosen, the program will guide the user in the calculation of the capacitor values. These calculatio ns are based on the nonidealities of the OTAs included in the standard cell library for layout, in addition the design of special purpose OT A as another alternative is also considered. Furthermore, the program will develop the necessary input files for the layout generator. The f inal module is a modified version of AIDE2, a standard cell layout gen erator for switched-capacitor circuits. The input files to the modifie d AIDE2 is a C language program that describes the circuit (i.e., stan dard cells and their netlist). The output file is a CALTECH Intermedia te Format (CIF) file that is required for fabrication.