Koan/Anagram II: New Tools for Device-Level Analog Placement and Routing

This paper describes KOAN and ANAGRAM II, new tools for device-level analog placement and routing. A block place-and-route style from macrocell digital IC's has recently emerged as a viable methodology for the automatic layout of custom analog cells. In this macrocell style, parameterized module generators produce geometry for individual devices, a placer arranges these devices, and a router embeds the wiring. However, analog layout tools that merely apply known digital macrocell techniques fall far short of achieving the density and performance of handcrafted analog cells. KOAN and ANAGRAM II differ from existing approaches by employing general algorithmic techniques to find critical device-level layout optimizations rather than relying on a large library of fixed-topology module generators. New placement algo rithms implemented in KOAN handle complex layout symmetries, dynamic merging and abutment of individual devices, and flexible generation of wells and bulk contacts. New routing algorithms implemented in ANAGRAM II handle arbitrary gridless design rules in addition to over-the-device, crosstalk avoiding, mirror-symmetric, and self-symmetric wiring. Examples of CMOS and BiCMOS analog cell layouts produced by these tools are presented.