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Testing dynamic specifications, THD (total-harmonic-distortion), SNR(signal-to-noise ratio) and ENOB (effective-number-of-bits), of high-resolution sigma-delta (ÄÓ) converters is extremely challenging due to the requirement of spectrally pure test stimuli with at least 10dB better SNR and THD than converters being tested. In this work, digital pulse sequence at ÄÓ modulator output is made externally observable for test purposes and an optimized test stimulus is generated that maximizes the sensitivity of the modulator output spectrum to device nonlinearities and noise. Two methods for analyzing the observed spectrum are presented: (1) the dynamic specifications are predicted from the digital pulse sequence using prior alternative testing algorithms, and (2) model parameters of the modulator are computed from the modulator output using nonlinear equation-solving algorithms and subsequently used to determine the specifications. The latter allows diagnosis of the causes of failure. Software simulations and hardware experiments are performed to demonstrate the feasibility of the proposed techniques.
fast Fourier transform (FFT), Sigma-delta (ÄÓ), Analog-to-Digital converters (ADCs), dynamic specifications test, alternate test, device under test (DUT), design-for-test (DfT), built-in-self-test (BIST)

A. Chatterjee, A. Banerjee and S. Kook, "Dynamic Specification Testing and Diagnosis of High Precision Sigma-Delta ADCs," in IEEE Design & Test of Computers.
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