Magnetogalvanic approach to isolation of analog circuits

An isolation amplifier circuit is described that utilizes a magnetic field in combination with a magnetosensitive lateral bicollector transistor (magnetotransistor-MTr) to isolate input and output signals. The input signal is applied to a conducting coil via an input amplifier and voltage-to-current converter. The output signal is proportional to the collector current difference (/spl Delta/I/sub c/) of the MTr which is a linear function of the applied magnetic field. Temperature stability was achieved by microthermostating the magnetotransistor. A particular design of the isolation block is proposed, and experimental results are depicted. A dynamic range of more than 54 dB has been achieved at a bandwidth of 10 kHz. The nonlinearity was only 0.05%.<
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