A full-band waveguide SIS receiver with integrated tuning for 75-110 GHz

Abstract

The performance of a broadband SIS receiver with no mechanical tuning elements was scale modelled and tested. The mixer mount had a broadband waveguide to microstripline transition consisting of a 4-step Chebychev single ridge transformer. The last step of the ridge connected the waveguide to a microstripline circuit. The on-chip circuit consisted of a microstripline, which transmitted the rf and the local oscillator signals to the SIS mixer. Some chips included a thin film strip inductor in parallel with the mixer. Both the SIS element and the inductor had rfgrounds provided by 90" radial stubs. The inductor tuned out the junction capacitance to allow operation over the full frequency band. The SIS element can be a single junction or series array using Nb/AlO,/Nb mlayer tunnel junctions with areas as small as 0.5 pm2 and V (2mV) = 39 mV. Preliminary results indicated a DSB receiver n&e temperature of 65-80 K across the band measured at 4.4 K with an internal cryogenic rf hodcold source and with Tif= 21 K. With another device, we achieved a mixer noise temperature of 35 K at 100 GHz, increasing to 45 K at 79.5 and 110 GHz. Coupled mixer gain of up to +3 dB and negative dynamic resistance on the first photon step were observed. The lowest noise temperature was obtained for an untuned single junction mixer at 80 GHz; TR = 41 K and TM = 20 K were measured.

Photon induced noise in the SIS detector

“…Accurate measurement of SIS mixer noise have been made by several groups [4]- [6]. These measurements have provided valuable information about receiver sensitivity.…”

Submillimeter-wave detection with superconducting tunnel diodes

“…Using SIS circuits designed with integrated tuning, it is possible to build SIS mixers with no mechanical tuning which have excellent responsivity over an entire waveguide band at millimeter wavelengths [11,39]. These two mixers are quite different in their design, both should be reviewed for a good appreciation of the range of integrated tuning circuitry which is possible.…”

“…In this design, the input waveguide is coupled to a microstrip circuit with a 4-section Chebyshev single ridge transformer [39]. Nearly full WR-10 band coverage is achieved with no mechanical tuning.…”