In this paper, we present a technique for characterizing CMOS analog circuits based on directed intervals. The technique consists of an analog performance estimator and a characterization table generator. This characterization information may be efficiently used by the constraint transformation step in an analog synthesis system. We present a genetic algorithm based constraint transformation method, that exploits problem structure by using the circuit characterization information. We discuss the design of the genetic operators that capture the characteristics of the constraint transformation problem. The constraint transformation method that uses the characterization information was compared against one using a conventional genetic algorithm and the experimental results obtained demonstrate the effectiveness of the proposed approach. 1 Introduction Automatic synthesis tools that transform the description of a system at a higher-level of abstraction to a lower level typically consist...

This paper defines a VHDL-AMS subset for behavioral synthesis of analog systems. The subset includes language constructs for describing most of the functional aspects pertaining to analog systems. Besides, these constructs can be implemented with electronic circuits. Functional aspects, which can be expressed with the subset, relate to two interacting parts. The analog part continuously processes analog signals, while the control part generates control signals for configuring the flow of signals in the analog part. However, some language constructs have to be constrained or augmented, so that they become effective for synthesis. To motivate that constructs in the subset can be synthesized, we present, by means of an example, how VHDL-AMS programs are compiled into an intermediate format. The intermediate format can be either directly mapped to components from a component library, or used for further synthesis-related optimization steps. Finally, we discuss a complete experiment for spe...

This paper presents a top-down design methodology to synthesize mixed-signal systems described at behavioral level. Our methodology is intended to automate the synthesis process of analog CMOS integrated circuits. Also, the method enables the circuit description at high level of abstraction where complex systems are easier to specify. The behavioral models are represented by a set of simultaneous differential and algebraic equations (DAEs), which are written in VHDL-AMS using simple simultaneous and procedural statements. We present an algorithm to perform the topology selection process. As an example, a Dual-Tone Multiple-Frequency decoder is synthesized from behavioral model to analog CMOS transistor level. 1 Introduction The emerging analog hardware description languages will speed up the analog verification process and enable the analog designer to describe circuits at higher levels of abstraction. Analog integrated circuits have been typically designed at circuit, component and ...

In this paper, we present a constraint transformation and topology selection methodology that explores the system level parameter space to compute acceptable regions in the component parameter space. The search process of an underlying circuit synthesis tool could be confined to these regions of valid solutions. Experimental results showing the impact of parameter space exploration at a higher level on analog circuit synthesis are presented, demonstrating the effectiveness of this technique. 1 Introduction Crucial to a top-down analog design process [10] is an interfacing mechanism to communicate the specifications and constraints on the design elements used at one level with those at the next level. The task of transforming the high-level specifications onto module parameters is called Constraint Transformation [3]. Efficient automation of this task is one of the the most important steps in automating the design of analog and mixed analog-digital systems. There are two important asp...