Differential string DAC with improved integral non-linearity performance
First Claim
1. A differential string DAC comprising:
- a coarse DAC including a plurality of coarse resistors connected in series between first and second reference voltage leads;
a positive sub-DAC including a plurality of positive sub-DAC cells, each sub-DAC cell including a plurality of series-connected fine resistors; and
a negative sub-DAC including a plurality of negative sub-DAC cells, each sub-DAC cell including a plurality of series-connected fine resistors;
wherein each coarse resistor is electrically connected in parallel with one positive sub-DAC cell and one negative sub-DAC cell, said one positive sub-DAC cell and one negative sub-DAC cell are substantially symmetrically disposed about the coarse resistor.
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Accused Products
Abstract
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.
30 Citations
12 Claims
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1. A differential string DAC comprising:
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a coarse DAC including a plurality of coarse resistors connected in series between first and second reference voltage leads; a positive sub-DAC including a plurality of positive sub-DAC cells, each sub-DAC cell including a plurality of series-connected fine resistors; and a negative sub-DAC including a plurality of negative sub-DAC cells, each sub-DAC cell including a plurality of series-connected fine resistors; wherein each coarse resistor is electrically connected in parallel with one positive sub-DAC cell and one negative sub-DAC cell, said one positive sub-DAC cell and one negative sub-DAC cell are substantially symmetrically disposed about the coarse resistor. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A differential string DAC comprising:
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a plurality of coarse resistors connected in series between first and second reference voltage leads; and first and second pluralities of resistor strings, each resistor string including a multitude of series-connected fine resistors; wherein each coarse resistor is electrically connected in parallel with one resistor string of the first plurality and one resistor string of the second plurality, the one resistor string of the first plurality and the one resistor string of the second plurality are substantially symmetrically disposed about the coarse resistor. - View Dependent Claims (8, 9, 10, 11, 12)
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Specification