This eliminates any inaccuracies in the real-power calculation due to offsets in the voltage or current signals. The real-power calculation is derived from the instantaneous power signal. The instantaneous power signal is generated by a direct multiplication of the current and voltage signals. In order to extract the real-power component, the instantaneous power signal is low-pass filtered.The low frequency output of the energy meter IC is generated by accumulating this real-power information.The output frequency is therefore proportional to the average real-power. This average real-power information can in turn be accumulated by a counter to generate real-energy information.