A Novel Strategy for Flexible Placement and Routing of AVS Sensors on FPGAs

Adaptive Voltage Scaling (AVS) is a well-known technique in ASICs. However, the requirements for its application in FPGAs are quite different. AVS uses run-time knowledge to determine a favorable voltage/frequency operating point. There are many suggestions in the literature for the sensors to be used to gain this run-time knowledge. However, the specific placement and routing of each sensor instance is either ignored or manually defined by hard macros or directed routing. In this paper, we propose a new approach to sensor placement. We are able to omit strict constraints like directed routing and give more freedom to the EDA tool without compromising sensor accuracy by using a proper sensor calibration. As a result, we are able to avoid placement and routing conflicts between sensors and application design. This allows the use of larger sensors with significant routing delay. An extensive experimental evaluation proves the validity of our approach.