| 摘要 |
PURPOSE:To improve the linearity and also to stabilize the operation to power supply fluctuaion and temperature fluctuation by adoping a differential output form to an absolute value circuit used for a cascade connection type A/D converter. CONSTITUTION:An input voltage is subjected to voltage/current conversion by transistors 8A, 8B or the like. Further, a comparator 22 is operated and a current switch 21 is switched in response to the polarity of input to output an absolute value. When an input potential difference ic changed from the negative side, althrough the output is increased together with the increase in the input, when the potential difference exceeds zero and the polarity is changed the current switch 21 is changed over and the output voltage of an output terminal 20B is not increased dashed lines but decreased as in solid lines. On the other hand, since the current flowing to a load resistor 11A is a current shown in dashed lines, an output A is obtained at an output terminal 20A by shifting the level of the output by a voltage VS through the use of a current source 19, the said output and the other output B are crossed in two points as shown in the figure, and accurate conversion is attained. |
