| 摘要 |
PURPOSE:To obtain a circuit which can be easily incorporated into an integration circuit and compensates automatically the DC offset of an integration type A/D converter, by detecting digitally the DC offset and controlling a counter by the value of the DC offset. CONSTITUTION:A D/A conversion is applied first to a voltage source 11, and the difference from the ideal value is stored in a memory 15 in the form of a DC offset error. Then a digital comparator 16 compares the output of a counter 12 with the value corresponding to the error of the memory 15 when an A/D conversion is applied to the analog input of an input terminal 1. The counter 12 is reset when the value of the counter 12 is equal to the error of the memory 15, and the counting action of the counter 12 is started again and continued until the output of an analog comparator 6 is inverted. This count value is delivered in the form of the digital value. This digital output is turned into a digital output whose error component is compensated since the restart of the counter 12 is delayed by an amount equivalent to said error component. |
