Accurate Measurement of the rms of a Sine-wave by Means of Low-Cost rms-to-dc Convertes

In this paper firstly a low-cost non-inverter half-wave rectifier (HWR)-based rms-to-dc converter is designed for the measurement of the root mean square (rms) of a sine-wave. The accuracy of this converter is investigated as a function of the resistance errors and the HWR op amp input offset voltage. Then, the accuracy of the designed HWR-based rms-to-dc converter is compared with that of a true rms-to-dc converter through experimental results as a function of the sine-wave magnitude and frequency. The true rms-to-dc converter is a new generation, low-cost, and low-power converter. The performed comparison allow us to determine the situations in which each of the above rms-to-dc converter is most suited to be used in practice.