Takekazu Ishida

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A Ka-band monolithic low noise two stage amplifier has been developed using an AlGaAs/InGaAs/GaAs pseudomorphic HEMT with a gate length of 0.15 /spl mu/m. For a superior noise figure, the MMIC was optimized by inserting a low loss resonator type stabilizing circuit without sacrificing the gain performance. The amplifier has achieved a 1.0 dB noise figure(More)
This paper is the first to report on a V-band dual-mode MMIC mixer that provides a drain injected mode and a resistive mode with the same MMIC design. This design allows the device's impedances of a drain injected mode and a resistive mode to approach each other at a higher LO-power. The developed GaAs MMIC delivers excellent mixer performances in both(More)
This paper describes a 77-GHz three-stage driver amplifier integrated with a very compact 4-dB digital attenuator. The attenuator can provide successful suppression in the gain variation of the amplifier according to ambient temperature in practical use. In addition, the amplifier matching fashion using short stubs and series transmission lines helps(More)
The 1:1 salt of a new donor molecule, ethylenedithiotetrathiafulvalenothioquinone-ethylenedithio-1,3-dithiolemethide (1), with FeBr4- ion, 1 x FeBr4, was prepared and found to exhibit a room-temperature electrical conductivity of 4 x 10(-2) S cm(-1) and semiconducting behavior with an activation energy of 170 meV. The paramagnetic susceptibility obeyed the(More)
SUMMARY One of the fundamental problems in many-pixel detectors implemented in cryogenics environments is the number of bias and read-out wires. If one targets a megapixel range detector, number of wires should be significantly reduced. One possibility is that the detectors are serially connected and biased by using only one line and read-out is(More)
By the reaction of new donor molecules, bis(ethylenedithio)tetrathiafulvalenoquinone(-thioquinone)-1,3-dithiolemethides [BEDT-TTFVO (1) and BEDT-TTFVS (2)] with FeX3 (X = Cl, Br) in CS2/CH3CN, 1:1 salts of 1 or 2 with an FeX4- ion (1.FeX4 and 2.FeX4) were obtained as black needle crystals. Their crystal structures are very similar to each other, in which(More)
SUMMARY We propose a neutron diffractometer system based on MgB 2 thin film detectors and an SFQ signal processor. Small dimensions of MgB 2 thin film detectors and high processing capability of the single flux quantum (SFQ) circuits enable us to handle several thousand or more detectors in a cryocooler, leading to a very compact system. In addition, the(More)
Magnetization and heat capacity were measured down to 0.4 K in a 2:1 charge-transfer (CT) salt of a new donor molecule, ethylenedithiotetrathiafulvalenoquinone-1,3-dithiolemethide (1) with a magnetic FeBr(4)(-) ion (1(2).FeBr(4)). The Fe(III) d spins of FeBr(4)(-) ions were subject to apparently ferromagnetic interaction with each other through the(More)
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