A Statistical Digital Equalizer for Loopback-based Linearity Test of Data Converters

This paper presents a new built-in self test (BIST) method based on efficient digital equalization and spectral prediction techniques. The method enables accurate built-in characterization of the static performance parameters of data converters, and thus test and calibration costs can be significantly alleviated. Based on recent work on dynamic performance parameter characterization using a loopback test, the transfer function of a DAC in loopback mode is estimated with a spectral prediction technique and Chebyshev polynomials. A digital equalizer is designed to compensate for the non-linearity of the DAC in the pre-conversion stage, hence the ADC can be tested with the digitally calibrated analog signals. The digital equalizer overcomes accuracy limitations encountered in a traditional compensation technique, and thus a standard histogram test which may suffer from INL masking problems can be successfully applied. Simulation results are presented to validate the technique