FIRE: A Fundamental Identification and Replacement Method for Accurate Spectral Test Without Requiring Coherency

Achieving coherent sampling is one of the major bottlenecks to perform ADC spectral test, especially when high-precision instruments or high-performance frequency synthesizes are not readily available. If coherent sampling is not achieved, there could be huge leakage in the spectrum, which might lead to inaccurate test results. In this paper, a new fundamental identification and replacement method is presented that can completely eliminate the need for coherent sampling in spectral testing. A two-step fundamental identification method is used to very accurately estimate the noncoherent fundamental. Extensive simulation results show the functionality and robustness of the method. Measurement results obtained in industry labs using commercially available high resolution ADCs successfully validate the proposed method for both accuracy and robustness.