Leveraging FDSOI through body bias domain partitioning and bias search

In FDSOI, sophisticated body biasing schemes can greatly reduce leakage or improve performance as well as efficiency. This paper proposes algorithms to determine body bias domain candidates which then merge those to reach a desired number of domains. Domain candidates are determined using an activation based approach, analyzing mapped verilog netlists to identify which parts of the design are used under specified conditions. Body bias domain partitionings are then determined based on activation and the timing of the partitioned parts. The algorithms include a body bias assignment algorithm to reach given timing goals with multiple domains and cross-domain resource sharing. The approach is compatible with any synthesis optimization and is resource sharing aware. Using an implementation of the proposed algorithms, overall leakage can be significantly reduced in all scenarios while obtaining the same benefits of body biasing. The method is evaluated in STMicro's 28nm FDSOI and Renesas's 65nm SOTB.