Patent ID: 8004802

Claim:
An operational amplifier circuit for an arc fault circuit interrupter comprising a current sensor including a secondary and a processor including a number of inputs, said operational amplifier circuit comprising: a band pass filter comprising an input structured to be electrically interconnected with the secondary of said current sensor and an output; a rectifier circuit comprising: an operational amplifier comprising an input electrically interconnected with the output of said band pass filter and an output, a half-wave rectifier comprising an input electrically interconnected with the output of said operational amplifier, an output, and a forward voltage between the input and the output of said half-wave rectifier, and a voltage compensation circuit cooperating with the input and the output of said operational amplifier to compensate for said forward voltage; and an envelope detector circuit comprising an input electrically interconnected with the output of said half-wave rectifier and an output structured to be input by one of the number of inputs of said processor, wherein said envelope detector circuit further comprises an averaging circuit including an input electrically connected to the output of said envelope detector circuit and an output structured to output a short term average value signal to one of the number of inputs of said processor.