A Distributed Body-Biasing Strategy for Asynchronous Circuits

The fast evolving pace of electronic mobile devices have made mandatory to reduce power consumption without compromising the circuit performance or its robustness. Asynchronous circuits have demonstrated to be an excellent solution to help designing robust and energy-efficient circuits required for the Internet-of-Things and the mobile applications. Their local synchronization mechanisms, based on handshake protocols, make them perfectly suitable for exploiting dynamic power management techniques, such as Adaptive Body Biasing (ABB) in FD-SOI technologies. Indeed, the circuit activity is simply detected by using the already existing handshake signals, enabling the application of different ABB strategies with almost no modification to the original asynchronous circuit. As the synchronization mechanisms are local to small logic blocks, the ABB strategy is able to target from small to large body bias domains. In order to manage such a technique, an analog dedicated standard cell has been designed to body bias small regions. Depending on the body bias domain granularity, an appropriated number of these specific cells is inserted exactly as logic standard cells during the back-end operations. Additionally, the robustness of asynchronous circuits makes possible changing the transistor threshold voltage on-the-fly, a requirement for applying ABB schemes without complex power management issues.