| 摘要 |
PURPOSE:To obtain an AD converter capable of automating the corection of amplification factor with a simple circuit, by forming a feedback path for the amplification factor switching with a DA converter. CONSTITUTION:When a controller 14 receives a reference signal 21, the controller 14 controls a reference voltage source 16 and a switch 17 from lines 28 and 22, applies a prescribed reference voltage to an amplifier 11 and controls a feedback DA converter 12 controlling the amplification factor of the amplifier 11. In this case,the output of the amplifier 11 is digitized by an AD converter 13 and controls the amount of feedback so that the value is maximum. The output of the AD converter 13 is checked by an arithmetric device 15 as to whether or not the value is maximum. The device 15 sends a correction signal to bits by low order of the DA converter 12 when an error exists and controls the amount of feedback so as to make the error to zero. Further, the AD converter shown in a figure outputs an external signal from a terminal 18 to a terminal group 20 through AD conversion with a switch 17 changed over. |
