A Measuring System for Microelectric Power

In this paper we are mostly concerned with the measurement of electric micro power and energy. This parameter is essential to evaluate the energy efficiency of low power devices, such as wireless operated monitoring and control systems. It is also important to measure the standby power consumed by appliances and equipment while switched off. The measurement of power generated by harvesting systems is another field of application. It is, thus, important to implement power meters to accurately measure power below one watt. The common commercially available wattmeters are inaccurate for these low-power measurements for two main reasons: a limitation on the instrument dynamic range and the intermittent operating mode of some devices. Particularly critical is the current measurement, for the high gains required in most applications. In this paper a measuring system for micro electric power and energy is proposed. It operates for voltage up to 3 Vpp and current from 1 pA to 5 mA, corresponding to an electric power down to around a fraction of microwatt. In the following the system architecture is described, discussing also some experimental results obtained during the characterization test.