Performance-Aware Common-Centroid Placement and Routing of Transistor Arrays in Analog Circuits

Abstract

The common-centroid (CC) layout style is widely used to minimize the impact of variations among matched devices in analog blocks such as current mirror banks and differential pairs. This paper presents a constructive, performance-aware CC placement and routing algorithm for transistor arrays. Specifically, the proposed approach maximizes diffusion sharing, incorporates length of diffusion (LOD) based stress-induced performance variations, and mitigates resistive parasitics and electromigration (EM) hotspots, all of which are critical in modern technology nodes. The proposed algorithms are validated using cell- and circuit-level test cases in a commercial 12nm FinFET process. As compared to existing works, the cells generated using the proposed approach are shown to provide better performance in the presence of systematic variations, LOD, layout parasitics, and EM-induced degradation.