Behavioral modeling for high-level synthesis of analog and mixed-signal systems from VHDL-AMS

Abstract

High-level synthesis is highly demanded for managing the complexity of analog and mixed-signal system designs. However, synthesis methods are currently in their infancy. The absence of a high-level specification notation is an important limitation for the development of efficient synthesis methods. This paper presents a behavioral model and a VHDL-AMS subset for high-level synthesis of analog and mixed-signal systems. The model (named aBlox) offers a composition semantics for functionality description and an orthogonal declarative mechanism for expressing the performance requirements of a system. The model was developed after analyzing a large number of systems for telecommunication, signal processing, control engineering, and analog computing. The model expresses the meaning of: 1) analog and digital data; 2) continuous and event-driven functionality (behavior); 3) analog performance attributes; and 4) analog-digital interactions. The aBlox model serves as a foundation for defining a semantically sound VHDL-AMS subset for synthesis. Also, the VHDL-AMS subset is identified so that its constructs can be mapped to architectures of circuits. We introduce several restrictions to the VHDL-AMS instructions, such that their semantics match that of the aBlox model. To motivate the usefulness of the model and the VHDL-AMS subset, we present a case study that uses VHDL-AMS inputs.