Analog Layout Using ALAS-the software tool
An analog layout assistant (ALAS!) is presented that automatically generates common-centroid, interdigitated device pairs and passive components. The user inputs a minimum of input parameters and has the ability to interactively alter the parameters of the program. The program can be used in conjunction with any layout editor that imports CalTech Intermediate Format (CIF) layouts and is platform and technology independent.
ANALOG integrated circuits are typically highly sensitive to process variations. Interdigitation and commoncentroid layout can make key analog components less sensitive to process variation, but requires complicated and time consuming full-custom layout. This paper presents an analog layout assistant (ALAS!) that automatically generates matched and balanced CMOS components with minimal input parameters from the user. There are CAD programs that layout a transistor given the width and length, but these are typically embedded within large synthesis or layout tools which allow the user very little flexibility for critical components.