An apparatus for improving the accuracy of an exponential current digital-to-analog (IDAC) using a binary-weighted MSB

摘要

An apparatus of an exponential current digital-to-analog converter (IDAC) using a binary-weighted MSB to efficiently drive current controlled light emitting diode (LED) devices. The apparatus comprises of an exponential current digital-to-analog converter (IDAC) current source, a voltage buffer to create an active cascode at the output stage, and an error amplifier that by means of a DC-DC converter voltage loop imposes an appropriate voltage at the output of the IDAC, depending on the current load set to drive the LEDs. The definition of the apparatus involves defining an exponential LSB and exponential MSB current mirrors according to a defined methodology.