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High-frequency Clock Operation of Josephson 256-word x 16-bit RAMs

By Shuichi Nagasawa Hideaki, Hideaki Numata, Yoshihito Hashimoto and Shuichi Tahara


A Josephson 256-word x 16-bit RAM that includes a power circuit has been developed to enable high-frequency clock operation. This RAM consists of a 4 x 4 matrix array of 256RAM blocks, impedance matching lines, and signal amplifiers. A power-supply circuit, composed of a transformer and a Josephson regulator, is included in each 256RAM block. Fail bit maps for the 256RAM block were measured, and perfect operation with a 100% bit yield was obtained. The 256RAM block functioned up to a clock frequency of 1.07 GHz. We succeeded in feeding a large high-frequency current of more than 2 A into the entire 256-word x 16-bit RAM. The 256-word x 16-bit RAM therefore functioned up to a clock frequency of 620 MHz. I. INTRODUCTION Many Josephson RAMs have been developed [1]-[6]. However, RAM operation at a clock frequency of about 1 GHz has not been actually realized, because high-frequency powering for large currents reaching several amperes is very difficult. Therefore, a powering circuit suppl..

Year: 2007
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