This paper describes how to extend the capabilities of SIMULINK for the time-domain simulation of ZA modulators implemented by using switched-capacitor, switched-current and continuous-time circuits. considering the most important error mechanisms. The behavioural models of these circuits are incorporated into the SIMULINK environment by using C-language S-function blocks, which leads to a drastic saving in the simulation time as compared to previous approaches based on MATLAB functions. The outcome is a complete SIMULINK block library that allows interactive, fast and accurate simulation of an arbitrary ZA topology.EU ESPRIT IST Project 2001-34283 TAMES-2 Spanish CICYT Project TIC2001-0929/ADAVERE.Peer reviewed