<p>Embodiments of the present invention provide systems, devices and methods for efficiently calculating a true RMS values (either voltage (Vrms) or current (Irms) ) of an AC signal. The RMS value is generated from both high and low frequency components (IH, IL) of the AC signal without a high speed ADC being integrated within the system. The high frequency component is processed by calculating an average current waveform (IH) of the high frequency component and approximating a corresponding RMS value using a waveform factor. The waveform factor is effectively a scalar that relates the average current waveform of the high frequency component to an appropriate RMS value.</p>
