automated placement for custom digital designs
Custom layouts of digital blocks are often used in mixed-signal designs in order to meet the critical performance requirements. Unlike traditional standard-cell based digital placement, custom-cell based digital placement may need to consider special routing patterns and pre-wires, very high design utilization, topology placement constraints, etc. This talk will address several unique placement problems for custom digital designs. First, spine style routing is often used in custom digital designs because of limited layer routing; it is necessary for placement to consider the spine topology to improve the routability. Second, the cell-level oxide diffusion (OD) sharing can help to reduce placement area, if custom cells are designed with common power and ground portions. Third, placement also needs to consider the electrostatic discharge (ESD) issue by enlarging the spacing between some cells to avoid direct power ground path. Last but not least, placement migration is another important and challenging issue; the resulting placement should follow not only the physical hierarchy of the design but also all additional topology placement constraints so that the resulting layout can meet the performance requirements.
placement custom spine electrostatic discharge