Generating comparator thresholds using a rotating ring of resistors

A circuit comprising:

• a ring of resistors having resistors in series forming a loop and nodes between resistors;
• a plurality of switches, each controllable for connecting a node in the ring of resistors to a first reference level or to a second reference level;
• a shift register for generating control signals for the plurality of switches, wherein the control signals selectively connect a first selected node to the first reference level and a second selected node to the second reference level to generate a plurality of comparator thresholds at a plurality of pre-selected pairs of nodes in the ring of resistors;
• and
• an array of comparators to drive an array of digital-to-analog converter elements, wherein each comparator is connected to a respective pre-selected pair of nodes in the ring of resistors.

An integrated circuit comprising:

• a first circuit to generate a bit array which shifts by one position at a time;
• and
• a second circuit to output control signals based on the bit array, wherein the control signals selectively couples a first selected node in a ring of resistors to a first reference level and a second selected node in the ring of resistors to a second reference level to change the plurality of comparator thresholds at a plurality of pre-selected pairs of nodes in the ring of resistors;
• comparators to generate a unary code based on an input signal to each of the comparators and the plurality of comparator thresholds;
• and
• converter elements to convert the unary code into a quantized analog signal, whose error caused by element mismatch are reduced by the selective coupling of nodes to the first and second reference levels.