Modeling and simulation sigma-delta analog to digital converters using VHDL-AMS

The purpose of this paper is to introduce the approach of modeling and simulation of sigma-delta modulators using VHDL-AMS. In this paper is stressed that fast and efficient modeling and simulation methodology can be very helpful in the process of microsystem design. A few sigma-delta modulator structures are presented. From 1^st to 4^th order sigma-delta modulators and also a triple cascade structure are shown. The advantages and disadvantages of the presented structures are discussed. The optimal solution is submitted to use as part of a silicon microsystem. The proposed silicon microsystems are based on two major parts. The first part consists of chemical sensors whereas the second part consists of analog to digital converters, registers, buffers, etc. The analog to digital conversion is performed using the sigma-delta method. Modulators are modeled and tested with the application of a VHDL-AMS simulator. In this paper, the simulation results are presented, and discussion of the advantages of sigma-delta conversion in this kind of measurement is performed.