Performance Measurements of 8-Gsps 1-bit ADCs Developed for Wideband Radio Astronomical Observations

8-Gsps 1-bit Analog-to-Digital Converters (ADCs) were newly developed toward the realization of the wideband observation. The development of the wideband ADCs is one of the most essential developments for the radio interferometer. To evaluate its performance in interferometric observations, the time (phase) stability and frequency response were measured with a noise source and a signal generator. The results of these measurements show that the developed ADCs can achieve the jitter time less than 0.05 psec at the time interval of 1 sec, the passband frequency response with the slope less than 0.73 dB/GHz and the ripple less than 1.8 dB, and the aperture time less than 20 psec. The details of the developed ADC design, the measurement methods, and the results of these measurements are presented in this paper.