| 摘要 |
PURPOSE: A direct current offset compensating circuit is provided to variably establish a gain according to a direct current(DC) offset magnitude and widen an input dynamic range. CONSTITUTION: A variable gain unit(20) variably amplifies a DC offset caused between two differential output signals(Vo+,Vo-). A differential integrator(22) integrates an output signal of the variable gain unit(20) to feed an integrated result back to input signals of a differential circuit. The variable gain unit(20) includes an amplifier(20a) and resistors(R3,R4,R5,R6). In the variable gain unit(20), the gain is variably established by changing values of the resistors(R3,R4,R5,R6) according to the magnitude of the DC offset. The differential integrator(22) consists of the first and second transconductance amplifiers(22a,22b).
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