AHD languages-a must for time-critical designs

In this article, Brian Antao of Motorola Inc., presents an overview of the state-of-the-art in analog modeling and hardware description languages. The emphasis is on higher-level circuit and system behavioral models for modeling complete analog and mixed analog-digital systems. An essential component required for this level of modeling is a Hardware Description Language (HDL) to encode the models in a consistent manner which can be later simulated as well as used for design documentation. Hardware Description Languages are a prominent feature of the digital design process, and the newer generation of the mixed-analog-digital systems require compatible hardware description language support that provides for the analog sections. Two popular digital HDLs are VHDL and Verilog. To provide natural extensions to these existing digital standards, analog hardware description language (AHDL) standardization efforts are underway to develop analog extentions to VHDL, called VHDL-A, and to Verilog, called Verilog-A