A power metering ASIC with a sigma-delta-based multiplying ADC

There is interest on the part of electrical energy distribution companies in replacing the classical mechanical energy meter with a fully-electronic equivalent. The classic approach to such a measurement system uses instantaneous line current and line voltage detected by two sensors (e.g. current and voltage transformers) and applied to two sigma-delta ADCs. An alternative circuit converts the product of two analog input signals directly into digital format.<>