A JOSEPHSON-JUNCTION-BRIDGE TRACK-AND-HOLD CIRCUIT

This paper describes the design and test of a highspeed monolithic track-and-hold circuit (T/H) consisting of a Josephson-junction-bridge current switch and a superconducting storage inductor. The bridge, under the control of a common-mode clock current, switches a balanced, differential input current. The T/H was fabricated using a 5-mu m, 1000 A/cm(2) niobium trilayer process. Calculations and simulations of the TM predict 5-bit dynamic range, 4.6-bit effective de resolution, 750 MHz analog bandwidth, 725 ps acquisition time, 700 MS/s peak sampling rate, and an unlimited hold time. Measurements on the fabricated T/H verify the proper qualitative behavior of the TM and show that it has 5-bit dynamic range, 4.5-bit effective de resolution, 900 MHz analog bandwidth, and a 550 ps acquisition time, commensurate with a 900 MS/s sampling rate.