| 摘要 |
A differential string DAC is provided including a coarse DAC which includes a plurality of coarse resistors connected in series between first and second reference voltage leads. A positive sub-DAC includes a plurality of positive sub-DAC cells, each positive sub-DAC cell including a multitude of series-connected fine resistors. A negative sub-DAC includes a plurality of negative sub-DAC cells, each negative sub-DAC cell including a multitude of series-connected fine resistors. Each coarse resistor is electrically connected in parallel with one positive sub-DAC cell and one negative sub-DAC cell. The positive sub-DAC cell and negative sub-DAC cell are substantially symmetrically disposed about the corresponding coarse resistor. Due to the differential arrangement and symmetrical layout of the DAC, INL errors due to process gradients in one direction across the DAC are greatly reduced. Process gradients in a second orthogonal direction are not of great concern as they cause much smaller INL errors. |
