Synthesis of Adaptable Hybrid Adders for Area Optimization under Timing Constraint

• Authors: Yonghwan Kim;Sanghoon Kwak;Taewhan Kim
• Venue: ACM Transactions on Design Automation of Electronic Systems (TODAES)
• Year: 2012

Satisfying the timing constraint is the utmost concern in the integrated circuit design and it is true that most critical timing paths in a circuit cover one or more arithmetic components such as adder, subtractor, and multiplier of which addition logic is commonly involved. This work addresses the problem of redesigning the addition logic (in a form of hybrid adder) on a critical timing path to meet the timing constraint while minimally allocating the required addition logic. Unlike the conventional hybrid adder design schemes in which they assume uniform or specific patterns of input signal arrival times and minimize the latest timing of the output signals, our work extracts the required timing of each output signal as well as the input arrival times directly from the circuit and resynthesizes the addition logic by creating a customized hybrid adder that is best suited, in terms of logic area, for meeting the timing constraint of the circuit. Specifically, we propose a systematic approach of hybrid adder design exploration, basically following the principle of dynamic programming with well-controlled pruning techniques. This work is realistic and practically very useful in that it can be used as a timing optimizer to the computation-intensive circuits with a tight timing budget. We provide a set of diverse experimental data to show how much the proposed hybrid adder scheme is effective in meeting or reducing timing while maintaining the circuit area as minimal as possible.