Submillimeter superconducting integrated receivers: Fabrication and yield

Fabrication procedure and yield analysis of superconducting integrated receivers is reported. These chip receivers, apart from the quasi-optical SIS mixers, contain internal local oscillators and associated rf and de interfaces. Due to both complexity and design requirements of the integrated circuit, certain restrictions are applied to the standard Nb/Al/AlxOy/Nb SNEAP process. To obtain accurate area for micron-size SIS junctions and thickness for multi-layer SiO2 insulation, a few solutions and modifications were developed. The possibility of transfering this fabrication process worldwide has been proven experimentally

Superconducting chip receivers for imaging application

Experimental details of a unique superconducting imaging array receiver are discussed. Each pixel contains an internally pumped receiver chip mounted on the back of the elliptical microwave lens. Each chip comprises a quasi-optical SIS mixer integrated with a superconducting flux-flow oscillator (FFO) both fabricated from the same Nb/AlOx/Nb trilayer on a silicon substrate. Properties of the integrated lens antenna were studied using an externally pumped reference SIS mixer which showed antenna sidelobes below -17 dB and a receiver double side band noise temperature, T-RX(DSB), below 100 K within the frequency range 460 - 500 GHz that is close to the quantum noise. For the imaging array T-RX(DSB) = 150 K has been measured at 500 GHz using the internal flux-flow oscillator as a local oscillator (LO). A balanced SIS mixer was tested showing T-RX(DSB) <100 K within the range of 480 - 510 GHz using the internal LO. A computer system was developed to control simultaneously the de bias of the SIS mixer and the frequency and power provided by FFO. The system also performs automatic optimization of the receiver noise temperature

Design and fabrication of Cherenkov flux-flow oscillator

The Josephson Flux-Flow Oscillator (FFO) has been used as an on chip local oscillator at frequencies up to 650 GHz. The FFO linewidth of about 1 MHz was measured in the resonant regime at V <915 mu V for niobium - aluminum oxide - niobium tunnel junctions, while considerably larger values were reported at higher voltages. To overcome this fundamental linewidth broadening we propose a novel on chip Cherenkov radiation flux-flow oscillator (CRFFO). It consists of a long Josephson junction and a superconducting slow wave transmission line that modifies essentially the junction dispersion relation. Two SIS detectors are connected both to the long Josephson junction and the transmission line to evaluate available microwave power. The output power coming both from the long junction and the transmission line is estimated at different bias conditions

An integrated 500 GHz receiver with superconducting local oscillator

An integrated quasioptical receiver consisting of a planar double - dipole antenna, SIS mixer and superconducting Flux-Flow Oscillator (FFO) with matching circuits has been designed, fabricated and tested in the frequency range 420-530 GHz. The integrated receiver is very suitable for space applications because of its low size, mass and power consumption. All components of the receiver are integrated on a 4 mmx4 mmx0.2 mm crystalline quartz substrate using a single Nb-AlOx-Nb trilayer. The successful operation of the integrated receiver comprising a number of new crucial elements has been demonstrated. A DSB noise temperature as low as 140 K at 500 GHz and a tuning range of more than 100 GHz have been obtained. A comparison of the FFO with conventional external LO has been performed

Integrated submm wave receiver with superconductive local oscillator

A fully superconductive integrated receiver is very promising for submm space astronomy where low weight, low power consumption, and limited volume are required. The new versions of the integrated quasioptical submm wave receiver have been designed, fabricated and tested in the frequency range of 450-700 GHz. The integrated receiver chip comprises a planar double dipole antenna, SIS-mixer and on-chip superconductive Flux-Flow Oscillator (FFO) with matching circuits. The receiver noise temperature (DSB) as low as 140 K at 500 GHz has been obtained. A light-weight and low power consuming submm imaging array is under development. Each of 9 pixels of the array is realized by an all-Nb single-chip superconductive receiver, mounted on an elliptical silicon lens with anti-reflection coating. The experimental test results of one pixel receiver are presented. A computer based system is developed to control the operation of the integrated receiver

First implementation of the fully superconducting 500 GHz receiver with integrated flux-flow oscillator

An integrated quasioptical receiver consisting of a planar double dipole antenna, SIS mixer and a superconducting local oscillator with matching circuits has been designed, fabricated and tested. A Flux-Flow Oscillator (FFO) based on unidirectional viscous flow of magnetic vortices in a long Josephson tunnel junction is employed as a local oscillator. All components of the receiver are integrated on a 4 mm x 4 mm x 0.2 mm crystalline quartz substrate on a base of the same Nb-AlOx-Nb trilayer in one technological run. The receiver has been studied in the frequency range 360 - 490 GHz. A lowest DSB noise temperature of 470 - 560 K has been achieved within the frequency range 425 - 455 GHz. Test circuits each comprising a FFO and a SIS detector have been experimentally investigated at frequencies up to 850 GHz. A new reliable technique for measuring the spectral linewidth of the integrated oscillators has been developed; the possibility of frequency locking of a FFO to an external microwave source has been demonstrated. The spectral linewidth of a FFO has been measured in the frequency range 250 - 580 GHz; a linewidth as low as 200 kHz is obtained at 450 GHz