Calibration of an R2R ladder based current digital-to-analog converter (DAC)

A R2R ladder circuit, comprising:

• a plurality of resistors;
• a plurality of current sources;
• a plurality of auxiliary current sources associated with each of plurality of current sources;
• and
• a calibration sub-circuit associated with each of the plurality of current sources for calibrating the corresponding plurality of auxiliary current sources to provide
• an auxiliary current from at least one of a corresponding plurality of auxiliary current sources based on a determination of mismatch at the corresponding one of the plurality of current sources.

A current source unit circuit, comprising:

• a main current source, configured to output a main current;
• a plurality of auxiliary current sources, wherein each of the plurality of auxiliary current sources is configured to output a corresponding auxiliary current;
• and
• a plurality of switching elements configured to control outputting of the main current and auxiliary currents from the plurality of auxiliary current sources, wherein the switching elements are configured in accordance with each of a plurality of modes of operation of the current source unit circuit
• wherein the current source unit circuit is implemented using a BiCMOS-based implementation including at least one bipolar transistor implementing one or more of the main current source and the plurality of auxiliary current sources, and at least one MOS transistor implementing one or more of the plurality of switching elements.