FRoC 2.0: Automatic BRAM and Logic Testing to Enable Dynamic Voltage Scaling for FPGA Applications

In earlier technology nodes, FPGAs had low power consumption compared to other compute chips such as CPUs and GPUs. However, in the 14nm technology node, FPGAs are consuming unprecedented power in the 100+W range, making power consumption a pressing concern. To reduce FPGA power consumption, several researchers have proposed deploying dynamic voltage scaling. While the previously proposed solutions show promising results, they have difficulty guaranteeing safe operation at reduced voltages for applications that use the FPGA hard blocks. In this work, we present the first DVS solution that is able to fully handle FPGA applications that use BRAMs. Our solution not only robustly tests the soft logic component of the application but also tests all components connected to the BRAMs. We extend a previously proposed CAD tool, FRoC, to automatically generate calibration bitstreams that are used to measure the application’s critical path delays on silicon. The calibration bitstreams also include testers that ensure all used SRAM cells operate safely while scaling V_dd. We experimentally show that using our DVS solution we can save 32% of the total power consumed by a discrete Fourier transform application running with the fixed nominal supply voltage and clocked at the F_max reported by static timing analysis.