| 摘要 |
PURPOSE:To attain an A/D converter with high speed and high accuracy, through the operation of an UP/DOWN counter having a digital converted output that it follow to an analog input signal just after the start of A/D conversion and it is operated with increased A/D conversion accuracy after the following is done. CONSTITUTION:At the start of A/D conversion, a tracking detection circuit 10 is reset with an A/D conversion start signal inputted from a terminal 17 and an output of an D/A converter 7 follows analog signals in high speed. When the output of the D/A converter 7 catches up with the analog input signal passes ahead, an output of a voltage comparator 3 is inverted and the UP/ DOWN counter 18b is inverted from UP to DOWN or verse visa. Then the output of the D/A converter 7 is also changed inversely accordingly, crosses over the analog input signal again and the output of the voltage comparator 3 is inverted again. The output of the D/A converter 7 follows the analog input while repeating the operations above. |
