| 摘要 |
A circuit is disclosed which performs two functions: (1) it develops a D.C. voltage signal which is proportional to the difference between the D.C. voltage components of a first and a second voltage, each comprising a D.C. voltage component and an A.C. voltage component impressed thereon, and (2) it filters the A.C. voltage components of both the first and second voltages. This circuit comprises cascade-connected first and second networks, each comprising an operational amplifier, with the output of the first network coupled to the input of the second network. Said first voltage is supplied as an input to the first network, and said second voltage is supplied as an input to the second network. The second network develops a D.C. output signal that is representative of the difference between the D.C. voltage components of the first and second voltages.
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