Circuit improvements for a voltage multiplier

A voltage (or flux) multiplier is a device which multiplies applied SFQ pulses. Due to the quantum nature of an SFQ pulse the device can be used as a voltage (or flux) amplifier with a fundamentally accurate (integer) gain. Earlier we showed that the device can be used for improvement of dc and ac voltage standards. Recently we have found that a long voltage multiplier can display complex dynamic behavior, which can lead to undesirable collective oscillations. This report is devoted to theoretical optimization and experimental investigation of long voltage multipliers connected in series for dc current. Experimentally we have obtained accurate current steps with about 0.1 V voltage drop for a 5 mm/spl times/5 mm chip fabricated in Nb technology and tested at 4 K.