A Study on a Delay-Line-Based Ramp-Compare ADC for Radio Astronomical Applications

Realizing wider-bandwidth and lower-cost radio spectrometers which improves the observation efficiency is crucial in modern astronomy. In this study, we review a delay-line-based ramp-compare analog-to-digital converter (ADC) which has a potential to realize very high sampling speed up to ~100 GSas
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in exchange for quantization bit rate that is less important for radio astronomy observations. The demonstration of the prototype was successfully conducted and the astronomical signal was detected, while the observation efficiency was found to be low by ~20 %. To increase the efficiency, Fourier transform with non-uniform sampling interval is required to be implemented.