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MIXER DEVELOPMENT FOR HIFI BAND 2 (640 — 800 GHz)

Cornelia E. Honingh, M. Justen, R. Teipen, Thomas Tils, Karl Jacobs

Published Mar 1, 2002• 0 citations
OpenAlex

Abstract

We present a fixed tuned SIS waveguide mixer for 640-800 GHz. The waveguide and filter design has been done using 3D EM-Simulation to improve the accuracy of the design for the required large fractional bandwidth. In this frequency range we use standard Nb—Al20 3—Nb SIS junctions with an R NA product of approximately 15 ohm!Am 2 , and areas between 1 gm 2 and 0.4 firll 2 . The choice of tuning structure material is not directly obvious because the frequency range includes the niobium gap frequency at 700 Gliz. Therefore devices with a NbTiN ground plane and as a choice with a niobium or an aluminum top electrode are used Current best noise temperatures are 300 K at the lower frequency end of the band and 450 K at the high end of the band, measured with the prototype HIFI mixer at 4-8 GHz IF frequency, for a device with a niobium top electrode., Measurements and analysis of devices with different designs, and both integrated tuning structure top electrode materials will be presented. The accuracy of the RF mixer design will be evaluated.

Related papers

NbTiN Based Tuning Structures for Broadband Nb-Al 2 O >3 -Nb SIS Mixers from 640 GHz-800 GHz

S. Glenz, Sybille Haas, Cornelia E. Honingh +1 more

We present measurements with a prototype waveguide SIS mixer for band 2 (640 GHz – 800 GHz) of HIFI (Heterodyne Instrument for FIRST). The Nb/Al2O3/Nb junctions have an RnA product from 12–18 Ωμm. These junctions are embedded in microstrip circuits tuning out the device capacitance using a NbTiN ground layer and various top conductor materials such as NbTiN, Nb and Al. The NbTiN films are fabricated by DC magnetron sputtering which is optimized for a minimum value of the DC resistivity and for a high critical temperature by varying the sputter pressure, sputter power and Ar:N2 flow. Typical NbTiN film parameters for device fabrication are ρ = 120 μΩcm and Tc = 14.5 K. The best uncorrected noise temperatures we measured so far are for devices with NbTiN/SiO2/Nb tuning. At 4.2 K bath temperature, a standard Yfactor measurement yields uncorrected receiver noise temperatures of 350 K at 642 GHz and 500 K at 810 GHz for 1.5 GHz intermediate frequency. We discuss the effect of the various tuning circuit materials on the mixer performance. In addition, measurements at IF’s between 4 GHz and 8 GHz will be presented.

Softwaretechnik-Trends•Dec 1, 2001•0 citations

Broadband Array SIS Mixers for 780-880 GHz with Aluminum Tuning Circuits

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Abstract—As a building block for an 8-pixel 800 GHz array receiver at KOSMA we developed a low noise SIS mixer. The mixerblock is tunerless and similar to the "stamped waveguide cavity " mixers we have used from 345 GHz to 800 GHz before [1]. We embedded the SIS junction into a standard broadband tuning circuit, commonly used at lower frequencies. The circuit consists of a short end-loaded stub in series with two impedance transforming sections. For the 780-880 GHz band, we fabricated the electrodes of the tuning circuit as a combination of niobium and aluminum layers in different sequences. First heterodyne tests were performed on devices with a tuning microstrip circuit ground plane consisting of 40nm Nb with 200nm of Al on top and a top conductor consisting of a 70 nm thick Nb layer with a 280 nm thick Al layer on top. The Nb-Al2O3-Nb junction has an area of about 0.5 µm 2 and is fabricated with optical lithography. For anisotropic Nb etching, we use a RIE gas mixture of CCl2F2 and NF3. The Al2O3 barrier is removed with Ar sputter etching. Fabrication yield improved considerably when we introduced a light CMP-step after self-aligned SiO dielectric liftoff. For a SIS junction with RnA equal to 14 Ωµm 2, the RSubgap/Rn value of 15.4 is remarkably good. We measured uncorrected receiver noise temperatures around 400 K over the whole band from 780 to 880 GHz, with a best noise temperature of 370 K at 804 GHz. 1

•May 1, 2000•3 citations

Broadband NbTiN based SIS mixers for HIFI Band 2

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We present SIS waveguide mixer results in the frequency range 638-802 GHz at an IF frequency of 4-8 GHz. We use Nb/Al/sub 2/O/sub 3//Nb junctions with areas down to 0.6 /spl mu/m/sup 2/ defined by e-beam lithography and chemical mechanical polishing (CMP), embedded in low loss NbTiN/SiO/sub 2//Nb or NbTiN/SiO/sub 2//Al microstrip tuning circuits.

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In this paper we will present the design and realization of a double sideband SIS heterodyne mixer for the frequency range of 780-950 GHz. A NbTiN high Tc superconductor in combination with aluminum is used for a SIS junction tuning circuit. We use a double side waveguide probe with a fixed backshort tuner design which was optimized by means of a 3D EM-modeling software. Compact mechanical envelope of the mixer allows for a combination of several units in a focal plane array. We will present results of instantaneous bandwidth measurement for seven mixer units and compare it with theoretical predictions. We also present a heterodyne sensitivity test results for these mixers with the best achieved DSB mixer noise temperature of about 250 K (physical temperature 4.2 K) which is only several times higher than a quantum noise limit for these frequencies.

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Single Junction Design for 790-950GHz SIS Receiver

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Two years ago, we have fabricated and tested superconductor-insulator-superconductor (SIS) mixers based on Nb/AlN/NbN twin tunnel junctions for waveguide receiver operating in frequency range of 790 - 950 GHz, which demonstrated noise temperature from 250 K at low frequencies to 500 K at the high end of the band. Due to high current density of the junctions (up to 30 kA/cm2 ), a wideband design was realized. Based on result for twin junction, a new mixer design with single SIS junction was proposed and produced. The single junction design is expected to have narrower frequency range than twin-based one, but still wide enough, and provide better coupling in the middle of the band. In addition, the critical current suppression will be much better, than for twin junction, which has an intrinsic problem of difference between areas of individual junctions. The SIS junction in new design is made by Nb/AlN/NbN technology and incorporated in a microstrip line consisting of a 300 nm thick bottom electrode (ground plane) made of NbTiN and a 500 nm thick top electrode made of Al. The top Al electrode is passivated by the SiO2 layer for protection. The DC tects of the fabricated wafer shows, that optimization of the technology allowed to realize gap voltage of 3.2 mV even for junctions of 0.5 square micron area fabricated on the NbTiN bottom layer. The FTS and noise temperature measurement of new mixers will be done in the nearest future and will be presented in comparison with the twin junction design results at the conference.

•Apr 12, 2016•0 citations

A 100-GHz fixed-tuned waveguide SIS mixer exhibiting broad bandwidth and very low noise temperature

Sheng-Gai Shi, Takashi Noguchi, Junji Inatani

This paper presents design and performance data for a 100-GHz waveguide superconductor-insulator-superconductor (SIS) mixer, which is incorporated with a twin-junction device (i.e., two identical junctions connected in parallel through a tuning inductance) and a fixed-tuned broad-band waveguide mixer mount. The 100-GHz mixer is actually developed as a prototype of the 500-GHz one. The constructed 100-GHz SIS receiver results in an overall receiver noise temperature (DSB) of less than 40 K over the frequency range from 80-120 GHz, with a minimum value of just 20 K that is four times as large as the quantum limit (i.e., 4/spl planck//spl omega//k). Such a performance is comparable or even superior to those of the best mechanically tunable waveguide SIS receivers at the same frequency band. In addition, some interesting mixing behaviors related to this two-junction device are described in detail.

IEEE Transactions on Applied Superconductivity•Jan 1, 1997•22 citations
We present a fixed tuned SIS waveguide mixer for 640-800 GHz. The waveguide and filter design has been done using 3D EM-Simulation to improve the accuracy of the design for the required large fractional bandwidth. In this frequency range we use standard Nb—Al20 3—Nb SIS junctions with an R NA product of approximately 15 ohm!Am 2 , and areas between 1 gm 2 and 0.4 firll 2 . The choice of tuning structure material is not directly obvious because the frequency range includes the niobium gap frequency at 700 Gliz. Therefore devices with a NbTiN ground plane and as a choice with a niobium or an aluminum top electrode are used Current best noise temperatures are 300 K at the lower frequency end of the band and 450 K at the high end of the band, measured with the prototype HIFI mixer at 4-8 GHz IF frequency, for a device with a niobium top electrode., Measurements and analysis of devices with different designs, and both integrated tuning structure top electrode materials will be presented. The accuracy of the RF mixer design will be evaluated.
We present measurements with a prototype waveguide SIS mixer for band 2 (640 GHz – 800 GHz) of HIFI (Heterodyne Instrument for FIRST). The Nb/Al2O3/Nb junctions have an RnA product from 12–18 Ωμm. These junctions are embedded in microstrip circuits tuning out the device capacitance using a NbTiN ground layer and various top conductor materials such as NbTiN, Nb and Al. The NbTiN films are fabricated by DC magnetron sputtering which is optimized for a minimum value of the DC resistivity and for a high critical temperature by varying the sputter pressure, sputter power and Ar:N2 flow. Typical NbTiN film parameters for device fabrication are ρ = 120 μΩcm and Tc = 14.5 K. The best uncorrected noise temperatures we measured so far are for devices with NbTiN/SiO2/Nb tuning. At 4.2 K bath temperature, a standard Yfactor measurement yields uncorrected receiver noise temperatures of 350 K at 642 GHz and 500 K at 810 GHz for 1.5 GHz intermediate frequency. We discuss the effect of the various tuning circuit materials on the mixer performance. In addition, measurements at IF’s between 4 GHz and 8 GHz will be presented.
Abstract—As a building block for an 8-pixel 800 GHz array receiver at KOSMA we developed a low noise SIS mixer. The mixerblock is tunerless and similar to the "stamped waveguide cavity " mixers we have used from 345 GHz to 800 GHz before [1]. We embedded the SIS junction into a standard broadband tuning circuit, commonly used at lower frequencies. The circuit consists of a short end-loaded stub in series with two impedance transforming sections. For the 780-880 GHz band, we fabricated the electrodes of the tuning circuit as a combination of niobium and aluminum layers in different sequences. First heterodyne tests were performed on devices with a tuning microstrip circuit ground plane consisting of 40nm Nb with 200nm of Al on top and a top conductor consisting of a 70 nm thick Nb layer with a 280 nm thick Al layer on top. The Nb-Al2O3-Nb junction has an area of about 0.5 µm 2 and is fabricated with optical lithography. For anisotropic Nb etching, we use a RIE gas mixture of CCl2F2 and NF3. The Al2O3 barrier is removed with Ar sputter etching. Fabrication yield improved considerably when we introduced a light CMP-step after self-aligned SiO dielectric liftoff. For a SIS junction with RnA equal to 14 Ωµm 2, the RSubgap/Rn value of 15.4 is remarkably good. We measured uncorrected receiver noise temperatures around 400 K over the whole band from 780 to 880 GHz, with a best noise temperature of 370 K at 804 GHz. 1
In this paper we will present the design and realization of a double sideband SIS heterodyne mixer for the frequency range of 780-950 GHz. A NbTiN high Tc superconductor in combination with aluminum is used for a SIS junction tuning circuit. We use a double side waveguide probe with a fixed backshort tuner design which was optimized by means of a 3D EM-modeling software. Compact mechanical envelope of the mixer allows for a combination of several units in a focal plane array. We will present results of instantaneous bandwidth measurement for seven mixer units and compare it with theoretical predictions. We also present a heterodyne sensitivity test results for these mixers with the best achieved DSB mixer noise temperature of about 250 K (physical temperature 4.2 K) which is only several times higher than a quantum noise limit for these frequencies.
Two years ago, we have fabricated and tested superconductor-insulator-superconductor (SIS) mixers based on Nb/AlN/NbN twin tunnel junctions for waveguide receiver operating in frequency range of 790 - 950 GHz, which demonstrated noise temperature from 250 K at low frequencies to 500 K at the high end of the band. Due to high current density of the junctions (up to 30 kA/cm2 ), a wideband design was realized. Based on result for twin junction, a new mixer design with single SIS junction was proposed and produced. The single junction design is expected to have narrower frequency range than twin-based one, but still wide enough, and provide better coupling in the middle of the band. In addition, the critical current suppression will be much better, than for twin junction, which has an intrinsic problem of difference between areas of individual junctions. The SIS junction in new design is made by Nb/AlN/NbN technology and incorporated in a microstrip line consisting of a 300 nm thick bottom electrode (ground plane) made of NbTiN and a 500 nm thick top electrode made of Al. The top Al electrode is passivated by the SiO2 layer for protection. The DC tects of the fabricated wafer shows, that optimization of the technology allowed to realize gap voltage of 3.2 mV even for junctions of 0.5 square micron area fabricated on the NbTiN bottom layer. The FTS and noise temperature measurement of new mixers will be done in the nearest future and will be presented in comparison with the twin junction design results at the conference.
This paper presents design and performance data for a 100-GHz waveguide superconductor-insulator-superconductor (SIS) mixer, which is incorporated with a twin-junction device (i.e., two identical junctions connected in parallel through a tuning inductance) and a fixed-tuned broad-band waveguide mixer mount. The 100-GHz mixer is actually developed as a prototype of the 500-GHz one. The constructed 100-GHz SIS receiver results in an overall receiver noise temperature (DSB) of less than 40 K over the frequency range from 80-120 GHz, with a minimum value of just 20 K that is four times as large as the quantum limit (i.e., 4/spl planck//spl omega//k). Such a performance is comparable or even superior to those of the best mechanically tunable waveguide SIS receivers at the same frequency band. In addition, some interesting mixing behaviors related to this two-junction device are described in detail.