The Well Audio
Due to the tolerance of the resistors used in the ladder, the accuracy of the DAC without any calibration is around 15 to 17 bit, depending on the resistors mixing.
In the attached pictures you can see the voltage measured at DAC output for each bit and for all the bits.
A dedicated Windows app automatically sends the signals to the DAC and measures the output voltages for each bit.
The Windows app also manages a 7 1/2 digits DMM, so the measurement is fully automatized.
Then the application computes the measured data and provides the calibration file in order to correct the accuracy error.
Finally the calibration file is loaded into the FIFO lite, which provides the needed correction for each bit.
This way the accuracy of the DAC is increased to 22-23 bit.