A power measurement system for accurate energy profiling of embedded wireless systems

In this paper, we present a highly accurate but still cost-effective measurement solution for tracking the highly dynamic power consumption of wireless embedded systems. We extended the conventional measurement of a single shunt resistor´s voltage drop by using a dual shunt resistor stage with an automatic switch-over between both stages, which leads to a large dynamic measurement range of 50 dB (1μA to 100 mA) with an average measurement error smaller than 1.2 %. Using two zero-drift current sense amplifiers for measuring the voltage drop over two different sized shunt resistors together with a 16 bit SAR ADC for each of both amplifiers leads to a far better thermal noise behaviour and a higher total measurement resolution compared to a single shunt solution, providing a minimum invasive measurement system with a maximum voltage drop of 100 mV. Using a state-of-the-art Ethernet connection allows our measurement system to forward the power samples with up to 250 kHz sampling rate to any remote networked computer.