| 摘要 |
A new offset canceling circuit for a differential circuit is disclosed whose input offset voltage may be cancelled independent of the variation of the input level, accordingly, enables the cut-off frequency of the canceling circuit unchanged. The offset canceller of the invention provides a buffer amplifier and a filter. The filter includes a capacitance multiplier including an operational amplifier (Op-Amp) operating in the inverting mode and a capacitor connected between the input and output of the Op-Amp. The Op-Amp operating in the inverting mode whose closed loop gain is solely determined by resistors, and the capacitance of the capacitor is multiplied by the closed loop gain of the Op-Amp by the Miller effect.
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