A current-mode BIST structure of DACs

An effective and accurate current-mode built-in self-test (BIST) structure for DACs is presented. Differential V/I converters are used to convert the differences between the analog output voltages of the DACs and the voltage of references into currents. The offset error, gain error, integral nonlinearity (INL) and differential nonlinearity (DNL) are tested to examine whether they are within their acceptable ranges by a window current comparator. With a high performance integrator to generate a ramp signal as the reference for INL tests, the number of reference voltages can be greatly reduced such that the chip area overhead can be saved. High precision is also an advantage of this test structure due to the feature of the higher acceptable dynamic range in the current-mode design.