Hierarchical placement with layout constraints

In analog layout design, devices are required to be placed with matching, symmetry, and proximity constraints to reduce parasitic coupling effects and improve circuit performance. In addition to these basic placement constraints, there exist hierarchical symmetry and hierarchical proximity constraints due to circuit and layout design hierarchies. This chapter first introduces the hierarchical constraints induced by circuit and layout design hierarchies, and then presents a hierarchical placement approach to better consider these hierarchical constraints and effectively reduce the search space.