A Current Consumption Measurement Approach for FPGA-Based Embedded Systems

In this paper, an approach for the current-consumption measurement of a field-programmable gate array (FPGA)-based embedded system is presented. This approach is based on the current conversion to pulsewidth using the external-to-FPGA capacitor charging circuit and comparator. The pulsewidth is then measured using the timer synthesized inside the FPGA. Measurement uncertainty budget analysis is performed. It reveals the parameters mostly affecting steady-state current measurement uncertainty. Sources contributing to the budget of current measurement uncertainty include directly measured pulsewidth, manufacturing scattering of measurement setup component parameters, and their fluctuations in response to the measured current value. A calibration procedure enabling to reduce the influence of charging circuit component manufacturing tolerances on measurement uncertainty is suggested. The current measurement prototype is developed and tested. Measured pulsewidth jitter is estimated experimentally using the prototype. The jitter influence on measurement uncertainty is modeled by including the corresponding quantity in the measurement model. The influence of the temperature on measurement uncertainty is estimated using Monte Carlo simulation.