IEEE Transactions on Applied Superconductivity · 1997 · 15 citations · 8 references
EngineeringElectrical EngineeringPhysicsAntennasMicroelectronicsMicrowave EngineeringHigh-frequency Semiconductor DevicesMicrowave AntennasMicrowave Integrated CircuitsMicrowave MixersSuperconducting MaterialsSuperconducting Thin FilmsBandwidthConversion LossCritical Current DensityCritical TemperatureCurrent DensityNbn Thin FilmsReceiver NoiseReceiver Noise Temperature
We have studied the phonon-cooled hot-electron bolometer (HEB) as a quasioptical mixer based on a spiral antenna designed for the 0.3-1 THz frequency band and fabricated on sapphire and high resistivity silicon substrates. HEB devices were produced from superconducting 3.5-5 nm thick NbN films with a critical temperature 10-12 K and a critical current density of approximately 10/sup 7/ A/cm/sup 2/ at 4.2 K. For these devices we reached a DSB receiver noise temperature below 1500 K, a total conversion loss of L/sub t/=16 dB in the 500-700 GHz frequency range, an IF bandwidth of 3-4 GHz and an optimal LO absorbed power of /spl sime/4 /spl mu/W. We experimentally analyzed various contributions to the conversion loss and obtained an RF coupling factor of about 5 dB, internal mixer loss of 10 dB and IF mismatch of 1 dB.
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Large bandwidth and low noise in a diffusion-cooled hot-electron bolometer mixer
A. Skalare, W. R. McGrath, B. Bumble et al. · Applied Physics Letters · 1996 · 73 citations