Reduced code linearity testing of pipeline adcs in the presence of noise

Reduced code testing of a pipeline analog-to-digital converter (ADC) consists of inferring the complete static transfer function by measuring the width of a small subset of codes. This technique exploits the redundancy that is present in the way the ADC processes the analog input signal. The main challenge is to select the initial subset of codes such that the widths of the rest of the codes can be estimated correctly. By applying the state-of-the-art technique to a real 11-bit 2.5-bit/stage, 55nm pipeline ADC, we observed that the presence of noise affected the accuracy of the estimation of the static performances (e.g, differential nonlinearity and integral non-linearity). In this paper, we exploit another feature of the redundancy to cancel out the effect of noise. Experimental measurements demonstrate that this reduced code testing technique estimates the static performances with an accuracy equivalent to the standard histogram technique. Only 6 % of the codes need to be considered which represents a very significant test time reduction.