Offset calibration system

The offset correction system, comprising: A first full-scale range ADC, wherein a first of correcting circuit; A second full-scale range digital-to-analog converter, comprising a second of correcting circuit; During the offset correction of digital-analogue converter; the digital-to-analog converter of wherein an connecting the input of ADC; And domain adjusting circuit, an accumulating the predetermined technical an value of are, and corresponding to analogue-to-digital converter one of significant voltage voltage and corresponding to the digital-to-analog converter one of significant voltage voltage ratio; the value of the overhead is the 2 preselection power.