Efficient Spectral Testing With Clipped and Noncoherently Sampled Data

In built-in self-test (BIST) environment, clipping is hard to avoid if one wants to obtain full range performance of an analog-to-digital converter (ADC). This could be due to several factors such as circuit component mismatch, noise, clock jitter, and so on. Furthermore, coherency is a challenging task to implement in BIST as its accuracy requirement on frequency of input signal is extremely high. This paper proposes a new spectral testing method with the efficiency and accuracy similar to the straightforward fast Fourier transform, but it can simultaneously handle amplitude clipping and noncoherent sampling. By replacing a noncoherent and clipped fundamental with a coherent and unclipped fundamental, correct spectral specifications can be obtained. Simulation results show accurate spectral parameters of four ADCs with different resolutions. The proposed method is validated using measurement result of a commercial 16-bit ADC. The algorithm error is quantitatively bounded using theoretical analysis and also justified with simulation result.