| 摘要 |
PURPOSE:To constitute an adding circuit suitable for a multilevel system by providing the first and the second nodes for addition and subtraction between plural input currents and radices and a floating switch which is controlled in accordance with the result of comparison between the potential of the first node and the radix. CONSTITUTION:Two input variables X and Y are inputted to a current mirror 63, and the current mirror 63 outputs a current having a value X+Y to plural drains. A current source 50 having a radix r-0.5 is connected to one drain of the mirror 63 at a node 65. As the result, a floating switch 61 is turned on when the input variable X+Y is equal to or larger than r-0.5. The other drain of the mirror 63 is connected to a node 64 between the gate of a current mirror 67 and the switch 61. Consequently, the current X+Y is outputted to an output terminal 68 of the current mirror 67 when the switch 61 is turned off, and the value (r) of a current source 62 is flowed to the node 64 and a current 0 is outputted as the result when the switch 61 is turned on. |
