Patent ID: 7808062

Claim:
A signal isolator for providing at an output thereof representations of input currents provided therein from a source of such currents, said signal isolator comprising: an input conductor suited for conducting said input currents therethrough and supported on a substrate; a bridge circuit suited for electrical connection to a source of electrical energization, said bridge circuit comprising a pair of series circuit members electrically connected in parallel with one another supported on a substrate with each series circuit member having a magnetoresistive member electrically connected in series with a current value controller at an output terminal thereof and which has also a control terminal at which magnitudes of currents present at said output terminal can be selected, said magnetoresistive members each being formed of magnetoresistive, anisotropic, ferromagnetic thin-film layers at least two of which are separated from one another by a nonmagnetic layer positioned therebetween to thereby have a resistance versus applied external magnetic field characteristic that is substantially linear for at least relatively small externally applied magnetic fields about a field value selected by that magnitude of current present at said current value controller output terminal as determined at least in part by a variable reference signal coupled to said current value controller control terminal from an electrical reference source, and with at least one of said magnetoresistive members being adjacent to, yet spaced apart from, said input conductor to thereby be electrically isolated from any direct circuit interconnection therewith but positioned so that said magnetoresistive member is in those magnetic fields arising from said input currents; and a differential amplifier having a pair of inputs each electrically connected to both said magnetoresistive member and said current value controller at said output terminal thereof in a corresponding one of said bridge circuit series circuit members, and having a pair of outputs each electrically connected to a corresponding one of said current value controllers at said control terminal thereof.