Ramp testing of ADC transition levels using finite resolution ramps

A common strategy for testing ADCs involves applying a ramp waveform to the converter, collecting a histogram of the converter response, and computing the transition levels. High resolution converters require high resolution sources with tight linearity to implement the test. A method is described which excites the ADC with an imperfect ramp whose resolution is comparable to the ADC noise. The transfer characteristics are extrapolated from the resultant response. The method recovers the threshold value with the same number of samples that are required by the classic ramp histogram.