Digitizer error extraction in the nonlinearity test

Measuring distortion using sources and digitizers that are nonlinear presents a difficult testing problem. A novel test method using digital signal processing (DSP) techniques is presented to address the error of the digitizer. A Taylor series representation is used to model the distorted digitizer and the device under test (DUT). A set of simultaneous equations can be constructed by considering the frequency contents of the digitized signal. These simultaneous equations can be solved to eliminate the error of the digitizer and give the nonlinearity of the DUT by itself. Additive Gaussian noise is assumed when analyzing errors in computation and during data acquisition. Simulation and experimental results support the analysis.