1 GHz clock operation of Josephson RAMs

Abstract

A Josephson 256 word×16 bit RAM that includes a power circuit has been designed to enable high-frequency clock operation. This RAM consists of a 4×4 matrix array of 256 RAM blocks, impedance matching lines, and input signal amplifiers. A power-supply circuit, composed of a transformer and a Josephson regulator, is included in each 256 RAM block. Fail bit maps for the 256 RAM block were measured, and perfect operation with a 100% bit yield was obtained. The 256 RAM block functioned properly at a high clock frequency of 1 GHz with less than 3 mW of power dissipation from an external power source.