Patent ID: 6577139
Filing Date: 2003-06-10
Classification: H03H

Abstract:
An impedance converter module comprising:a phase reversal circuit to receive a 2-wire excitation signal at first and second terminals, and to provide a polarized excitation signal with a predetermined polarity based on the 2-wire excitation signal; a series current path comprising a sense resistor connected in series with a variable impedance source, the polarized excitation signal being applied across the series current path; an output-voltage-sense circuit to provide an output-voltage-sense signal based on a voltage across the series current path; a current mirror to provide a drive signal to a ratiometric device based on current flowing through the series current path; differential amplifiers to receive a ratiometric response signal from the ratiometric device, and to output measurement signals based on the ratiometric signal; and a summing node to combine the measurement signals to provide a single-ended ratiometric signal; wherein the variable impedance source is controlled to provide a two-wire response signal at the 2-wire terminals based on the single-ended ratiometric signal and the output-voltage-sense signal.