National Institute of Information and Communications Technology, Incorporated

Inter-university Research Institute Corporation National Institutes Oe Natural Sciences

Yoshinori Uzawa

Zhen Wang

Takafumi Kojima

A low-noise wide band amplifier is realized utilizing a superconductor-insulator-superconductor (SIS) junction, quasiparticle frequency mixers connected in tandem or in cascade, a first quasiparticle mixer performs first frequency mixing with use of a first local signal having a frequency not less than twice a frequency of an input signal to the first quasiparticle mixer, a second quasiparticle mixer performs second frequency mixing with use of a second local signal having a frequency not more than twice a frequency of an input signal to the second quasiparticle mixer, and signal amplification is performed through frequency conversion by extracting, from among a plurality of signals generated with the first and the second frequency mixing, a signal in a frequency band not more than a frequency band of the signal before the first frequency mixing and the second frequency mixing, using a transmission line or a filter.

Low-noise microwave amplifier utilizing superconductor-insulator-superconductor junction

It is an object to provide a tuning circuit which has large fractional frequency band width, for example frequency band of the return loss of less than &#x2212;10 dB. The tuning circuit is composed of a superconductor microstrip lines, a superconductor distributed tunnel junction elements, a signal input part and a signal output part. It comprises at least a superconductor microstrip line and at least two superconductor tunnel junction elements, wherein the microstrip line and the tunnel junction element are connected alternately. The microstrip line and the tunnel junction element are half-wavelength of an input signal at a center frequency. A quarter-wavelength impedance transformer is comprised between a signal input part and a half-wavelength tunnel junction which is nearest to the signal input part.

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Tokyo, Japan

Yoshinori Uzawa