Measuring code edges of ADCs using interpolation and its application to offset and gain error testing

Measuring analog threshold voltage between two different digital codes is a common test performed during production testing of ADCs. Due to the noisy nature of analog signals, this test can take considerable amount of costly test time. This paper presents a fast algorithm for measuring code edges of ADCs. In this method, a gaussian distribution is assumed for noise in ADCs and the code edges are determined by interpolating the inverse cumulative distribution of the gaussian function. A fast testing method for guaranteeing the specifications on offset and gain error is developed as a corollary to the code edge measuring technique. Practical issues in implementing this technique in production testing are discussed. Production test results show excellent repeatability and large saving in production test time