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Takanori KUBO Shigeo TANAHASHI Kazuhiro KAWABATA Ryoji JIKUHARA Gentaro KAJI Masami TERASAWA Hiroshi NAKAGAWA Masahiro AOYAGI Youichi HAMAZAKI Itaru KUROSAWA Susumu TAKADA
A new built-in drive circuit for superconducting Josephson LSI circuits has been designed and fabricated in a ceramic multichip module. The drive circuit consists of an impedance matching circuit and a DC bias current feeding circuit to supply a two-phase power current to Josephson chips at a microwave frequency. The impedance matching circuit was designed based on a quarter wavelength stripline. A balanced stripline configuration was introduced to reduce the fluctuation of ground potential. Tungsten layers were used to make the drive circuit in a multilayer ceramic substrate of the multichip module. Whole circuit was successfully packed in a volume of 76 mm38 mm1.7 mm. The gain of microwave current were 20 dB around 1.2 GHz and 23 dB around 3.6 GHz, which were in good agreement with the simulated current gain.
Shigeo TANAHASHI Takanori KUBO Ryoji JIKUHARA Gentaro KAJI Masami TERASAWA Munecazu TACANO Hiroshi NAKAGAWA Masahiro AOYAGI Itaru KUROSAWA Susumu TAKADA
A superconducting multichip module using Nb/Polyimide on a mullite multilayer ceramic substrate has been developed for Josephson LSI circuits. The Nb/Polyimide stacked layers on the mullite multilayer ceramic substrate makes it possible to fabricate superconducting off-chip wiring for control signal line. We named the MCM "SuperMCM". The superconducting transmission line is designed to have the characteristic impedance of 14 Ω to match with the Josephson devices. The superconducting critical temperature, critical current density and critical current at a via hole are 8.5 K, 8.2105 A/cm2 and 2.5 A, respectively. The SuperMCM also provides matching circuits employing quarter wavelength striplines for driving Josephson LSI circuits at a microwave frequency, and DC bias circuits in the mullite multilayer ceramic substrate. The characteristics of the matching circuit is measured in the frequency range up to 3.6 GHz and the microwave current gain of 20 dB is obtained at 1.2 GHz, which revealed that the SuperMCM has the ability to drive the Josephson LSI circuits at more than 1.2 GHz clock speed.