Increasing the robustness of the resonator based ADC testing

Testing Analog-to-Digital Converters is important for both the manufacturer and the consumer. One of the test procedures require to excite the ADC with a pure sine wave, and calculate the errors (SINAD, SNR, ENOB, THD+N etc.) of the Device Under Test from the acquired signal. The error definitions are based on the difference between the reference signal and the measured one. Usually a fitted sine curve serves as reference waveform. In [1] and [2] we proposed a resonator based approach to generate the reference waveform in the case of very long time records in order to overcome on the large initial parameter sensitivity of sine fitting. In this paper we will investigate the noise sensitivity of different extensions of the resonator based approach, and propose a robust solution finally. We will examine (a) the effect of damping the error in the feedback loop of the resonator structure, (b) the effect of damping the feedback of the AFA structure, (c) the effect of using Block Adaptive Fourier Analyzer (BAFA) instead of Adaptive Fourier Analyzer (AFA).