High-resolution Measurement by a High-Tc Superconductor Sampler

3⁄4We measured a signal current waveform by using a high-Tc superconductor (HTS) sampler with a 1-ps delay between every sampling point. The maximum time differential obtained in the measured waveform was 12 mA/ps with 2.5-mA current sensitivity at 25 K. This result guarantees that the sampler is able to measure current waveforms correctly when their maximum time differential is less than 12 mA/ps. The superior time resolution was achieved by using high-speed single-fluxquantum pulses generated in the HTS circuit. A unique feature of the sampler is that it directly measures the current with picosecond time-resolution and microampere currentresolution. Current measurement flowing through wiring in a semiconductor large-scale integrated circuits is a promising application for the HTS sampler.