A variable hysteresis aperturing method for superconducting counting A/D conversion

The authors present an aperturing method for superconducting counting A/D (analog/digital) converters. The scheme, called TRAP (time release after aperturing of pulses), utilizes a large β_L two-junction SQUID (superconducting quantum interference device) quantizer and plays on the ability to control the amount of hysteresis available in such a SQUID. Incoming information from the analog signal can be either immediately processed by the quantizer or trapped and outputted at a later time. The author explains how this control can be used to form a picosecond aperture for counting A/D converters, eliminating pulse-skipping problems. SPICE simulations confirm the ideal behaviour of the TRAP