Improvements in the millimeter-wave subsystem for Josephson junction array voltage standard systems

Improvements in the millimeter-wave subsystem have been accomplished to provide higher millimeter-wave power to a Josephson junction array chip. The 94-GHz oscillator output power has been increased to 90 mW by incorporating an InP Gunn diode. The frequency stability of the InP Gunn oscillator is maintained at 10/sup -10/ of the center frequency. A low-loss dielectric waveguide has been installed in liquid helium to reduce the insertion losses of the millimeter waves to 3 dB/2.5 m. The improved millimeter-wave system has been confirmed to operate well in a Josephson junction array voltage standard system for voltage calibration at the 1-V level with the specified accuracy.<
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