| 摘要 |
PURPOSE:To increase the number of degrees of freedom of the gain by dividing the 2R terminal resistance of the R-2R ladder resistance circuit forming the feedback circuit of the operational amplifier by XR and (2-X)R by connecting these division points to the inversion input terminal. CONSTITUTION:R-2R ladder resistance circuit 20 having bit switches 3-1-3-n is used as the feedback network of operational amplifier 1. The resistance of 2R for terminal of ladder resistance circuit 20 is divided by XR and (2-X)R, and these division points are connected to inversion input terminal 12 of operational amplifier 1. Thus, the resistance at the view of the operational amplifier 1 side from point A is 2R, and relation R-2R is kept. Further, the gain variable range is set freely by selecting X. |
