| 摘要 |
PURPOSE:To reduce an effect of floating capacity due to an input switch of a multiplexer and to eliminate the interference between the input electric quantities, by using a switching element which is controlled by the control signal supplied from outside and can control the internal impedance. CONSTITUTION:When an A/D conversion is finished for the voltage V1 which is held at a sample holding circuit SH1, a multiplexer MPX is controlled to a nonselection state. Then an electronic switch SW1 is turned on in case the MPX selects no input channel. In other words, the electric charge which is charged to the floating capacity C0 is discharged through the switch SW1 since the SW1 is connected in parallel with the capacity C0. After the electric charge is thoroughly discharged, the SW1 is turned off to switch the input of the MPX to an input channel CH2. |
