We present a new synthesis strategy that can automate fully the path from an analog circuit topology and performance specifications to a sized circuit schematic. This strategy relies on asymptotic waveform evaluation to predict circuit performance and simulated annealing to solve a novel unconstrained optimization formulation of the circuit synthesis problem. We have implemented this strategy in a pair of tools called ASTRX and OBLX. To show the generality of our new approach, we have used this system to resynthesize essentially all the analog synthesis benchmarks published in the past decade; ASTRX/OBLX has resynthesized circuits in an afternoon that, for some prior approaches, had required months. To show the viability of the approach on difficult circuits, we have resynthesized a recently published (and patented), high-performance operational amplifier; ASTRX/OBLX achieved performance comparable to the expert manual design. And finally, to test the limits of the approach on industrial-sized problems, we have synthesized the component cells of a pipelined A/D converter; ASTRX/OBLX successfully generated cells 2-3/spl times/ more complex than those published previously.

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Synthesis of high-performance analog circuits in ASTRX/OBLX

This tutorial paper gives an overview of the history and present state of the art in symbolic analysis of electronic circuits at the so-called circuit level. Symbolic analysis is defined as a technique generating a closed-form analytic expression for a circuit characteristic with the circuit's elements represented by symbols. Such analytic information complements the results from numerical simulations. The paper then describes the different application areas of symbolic analysis for the design of analog circuits. Symbolic analysis is mainly used as a means to obtain insight into a circuit's behavior, to generate analytic models for automated circuit sizing, and in applications requiring the repetitive evaluation of circuit characteristics. Next, the present capabilities and limitations of symbolic analysis, both in functionality and efficiency, are discussed. The major symbolic analysis methods are presented, and algorithmic details are provided for symbolic approximation, hierarchical decomposition, and symbolic distortion analysis. Finally, existing symbolic simulators are compared, and directions for future research are pointed out. >

Symbolic analysis methods and applications for analog circuits: a tutorial overview

This paper introduces an automated circuit design system for the evolution and subsequent invention of CMOS amplifiers. The proposed system relies on a mix of genetic programming and a new topology-independent design optimization method referred to as current-flow analysis. Genetic programming evolves new circuit topologies from the collection of primitive devices and basic building blocks. Current-flow analysis screens and corrects circuits using topology-independent design rules. Experimental results show a promising improvement on the design of operational amplifiers that make the automated analog design environment using genetic programming a lot more practical.

The invention of CMOS amplifiers using genetic programming and current-flow analysis

A method of specifying design parameters is provided for configuring circuits for programmable ICs. A design database describing a circuit is displayed in table-based format on a computer screen display. The design database may include a memory map including data to be placed in bit-storage space in the target programmable IC. This design database requires no schematics or HDL description of the circuit, even for complicated application-specific circuits. The desired parameters are entered by the user, typically using toggle buttons, pull-down menus, or keyboard entry. The selected parameters are then entered into the design database, thereby configuring the design database in accordance with the selected parameters. Next, the design database is transmitted over a data communications link such as the internet to a second computer, on which the compilation software resides. The design is then compiled and the resulting netlist is transmitted back to the originating computer. In one embodiment, a schematic symbol or HDL instantiation is also generated by the second computer, and transmitted back to the originating computer.

Method for configuring circuits over a data communications link

An analog circuit design environment and its key features are presented These are multifunctionality, advanced modeling, novel simulation approaches, general sizing algorithms, hierarchy, and automatic and interactive layout generation capabilities Also, several developments in the field of analog design automation are discussed >

Towards an analog system design environment

An analog design automation system is presented. The system is capable of designing, analyzing and optimizing analog circuits in MOS, bipolar or BiCMOS technologies. Its main feature is that it is open to the user's expertise. The expertise that can be introduced is knowledge concerning the topology and functionality of a customer circuit, which can be complemented with knowledge about its device sizing sequence. Due to the fact that it is open, it assists and encourages designers in storing their expertise in a structured way, so that it can be reused. The tool includes Monte-Carlo analysis algorithms which ensure an extensive verification and characterization of the design. >

An open design tool for analog circuits

An open analog design system is presented that can generate layouts of analog cells and subsystems starting from desired functional specifications and a technology description which can be CMOS, bipolar, or BICMOS The design system includes model parameter verification, symbolic analysis, design, optimization, and automatic documentation of cells The schematics of the analog cells can be selected out of a library or can be entered by the designer Either a full description of the schematic is given or a new schematic is composed starting from a library of subblocks The layout generator, which is process portable, handles typical analog layout constraints during placement and routing All tools can be used in a full automatic mode or can be used interactively to allow more experienced designers to impose their point of view >

The ADAM analog design automation system

Basic sizing routines of a synthesis program for MOS analog circuits [1] are presented. A class of routines is given that allows the design of single components as well as basic analog structures for a large domain of operating conditions. These routines can have any of their characteristics imposed as input parameters or output variables. Moreover, a general valid routine useful to size circuits according to 1/f noise, offset and gain specifications is given.

http://ieeexplore.ieee.org/iel5/5468225/5468226/05468357.pdf

Sizing Algorithms for Linear Analog Circuits

The integration of a synthesis tool for analog circuit in a general design framework is presented. It is based on a schematic editor and uses the graphical interface to visualize results of the synthesis. Main features of the tool are openness to external topologies, technologies (CMOS and BiCMOS) extended characterization capabilities and integration in a general design framework. The synthesis part is done by the program IDAC. The tool is integrated into the design framework UNICAD developed by SGS Thomson. >

C. Meixenberger

Papers

An open design tool for analog circuits

The ADAM analog design automation system

Sizing Algorithms for Linear Analog Circuits

A schematic driven synthesis tool for analog circuits