| 摘要 |
A transformer-coupled isolation amplifier which has a minimally sized transformer, high common mode rejection, and a highly linear response over a wide dynamic range. A first chopper periodically alternates by 180 DEG the connection of the input through a high resistance to the primary of a small square loop pulse transformer. The secondary, with the end of the winding closest to the primary grounded, has the inputs of an operational amplifier placed across it. Negative feedback is provided around the amplifier to provide an apparent very low impedance across the secondary of the transformer. The negative feedback induces a current in the transformer secondary which cancels the flux produced by current flowing in the primary, thereby allowing usage of the transformer normally suitable only for high speed pulses. The output of the amplifier connects to a second chopper synchronous with the first to generate the amplified analog signal. A unique isolated power supply supplies power and switching signals for the first chopper.
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