Analytic macromodeling and simulation of tightly-coupled mixed analog-digital circuits

The approach discussed is based on the efficient integration of the analog simulator with an analytic digital macromodel via the mixed A/D circuit partitioning, error and timestep control, and latency checking schemes. While maintaining accuracy constraints at every timepoint, this approach efficiently decouples the digital processing completely from the iteration-based analog algorithms. The waveform information of the digital subcircuits is provided at each timepoint by an accurate digital macromodel, which is derived analytically from the technology files. Therefore, advanced CMOS technologies can be incorporated easily. The proposed technique has been integrated into MISIM, a flexible CAE system for mixed A/D verification and rapid technology characterization. Several mixed A/D benchmark circuits have been tested and the results show that MISIM provides accurate mixed A/D simulation capability with a speed advantage of up to three orders of magnitude over SPICE3.<>