Polarity compensating dual-string digital-to-analog converters (DACs), and related circuits, systems, and methods

摘要

Polarity compensating dual-string digital-to-analog converters (DACs), and related circuits, systems, and methods are disclosed. In embodiments disclosed herein, a secondary voltage divider of a dual-string DAC includes a switch logic unit. The switch logic unit is configured to compensate for polarity changes in the dual-string DAC to maintain monotonicity. Monotonicity means an output voltage of a DAC either increases or stays constant for monotonically increasing functions or either decreases or stays constant for monotonically decreasing functions given an incremental change in a DAC input code. The switch logic unit is configured to compensate for polarity changes in the input voltage from the primary voltage divider to the secondary resistor string. The switch logic unit is configured to select a secondary switch among the plurality of secondary switches in a secondary voltage divider, to divide an input voltage based on a polarity indicator and a DAC input code, to maintain monotonicity.

主权项

1. A secondary voltage divider of a dual-string digital-to-analog converter (DAC) comprising:
a secondary resistor string comprising a plurality of secondary resistors, the secondary resistor string comprising a plurality of secondary resistor nodes, the secondary resistor string configured to divide a selected primary DAC output voltage applied as a secondary DAC input voltage across the secondary resistor string into a plurality of divided voltage levels across the plurality of secondary resistors; a secondary switch unit comprising a plurality of secondary switches each coupled to a respective secondary resistor node among the plurality of secondary resistor nodes, each secondary switch among the plurality of secondary switches configured to select a current secondary resistor node among the plurality of secondary resistor nodes of the secondary resistor string to provide a divided secondary voltage level across the current selected secondary resistor node to be applied to a DAC output voltage node of the dual-string DAC; and a switch logic unit configured to:
receive a secondary DAC input code and a polarity indicator indicating a polarity of the secondary DAC input voltage; andselect a current secondary switch among the plurality of secondary switches based on the polarity indicator and the secondary DAC input code to select a secondary resistor node coupled to a current selected secondary switch, to cause the divided secondary voltage level across the current selected secondary resistor node to be applied to the DAC output voltage node of the dual-string DAC.