Split-drain MOST based circuit for measuring electric power

An arrangement of P-channel split-drain MOS transistors is presented, which detects an applied magnetic field, whose flux density is B[Tesla], and produces an output current signal that is proportional to the product B×e, where e[Volt] is an applied voltage signal. When B and e are respectively proportional to the current and voltage on a test load, the output signal produced by the circuit is a measure of the corresponding power. The core of this circuit was fabricated in standard 0.8µm CMOS technology and 64 units of this core were connected in parallel to make up the prototype chip. Measurements of this circuit have shown that a low-cost monolithic solution for power metering is technically feasible.