Characteristics of voltage multipliers for a Josephson D/A converter

We present design and experimental results of a voltage multiplier (VM) that is a main component of a Josephson D/A converter based on single flux quantum pulses. We have analyzed the VM operation through detailed simulations and have re-designed the circuit. The amplitude of the constant-voltage step for a 64-stage VM with the new design is 80 (mu)A at 10 GHz of an input frequency, which is sufficiently large for D/A converter applications.