I/O pad assignment based on the circuit structure

Abstract

An algorithm is presented for assigning off-chip I/O pads for a logic circuit. The technique, which is based on the analysis of the circuit structure and path delay constraints, uses linear placement, goal-programming, linear-sum assignment and I/O pad clustering to assign locations to I/O pads. The I/O pad assignment is then used by placement tools. Experimental data show that as a result of using the I/O pad assignment procedure, the total interconnection length and circuit delay (after placement and routing) are reduced by 8-15% and 3-4%, respectively. This technique is general and can handle I/O pad assignment prior to logic synthesis or detailed placement procedures.<>