Some recent developments in the design of SIS mixers

Balanced receivers are under development at the Caltech Submillimeter Observatory (CSO) for the 230/460 GHz and 345/660 GHz atmospheric windows. The mixers are tunerless, implemented in a balanced configuration, have a 4-8 GHz IF, and can be used in dual frequency observation mode. As shall be seen, the balanced arrangement provides a high level of amplitude noise immunity and allows all of the available LO power to be used. In turn, this permits complete automation of the receivers by means of synthesized LO source(s). A disadvantage of balanced mixers is, perhaps, that the sidebands at the IF remain convolved (DSB), unlike sideband separating (2SB) receivers. The latter, however are unbalanced and do not have the noise and LO injection advantages of balanced mixers. For the CSO, balanced mixers covering the range 180-720 GHz were judged most promising to facilitate many of the astrophysical science goals in the years to come.In parallel, a dual polarization 280-420 GHz continuous comparison (correlation) receiver is in an advanced state of development. The instrument has two beams on the sky; a reference and a signal beam. Using only cooled reflecting optics, two polarizing grids, and a quadrature hybrid coupler, the sky beams are coupled to four tunerless SIS mixers (both polarizations). The 4-12 GHz mixer IF outputs are, after amplification, correlated against each other. In principle, this technique results in flat baselines with very low RMS noise, and is especially well suited for high redshift Galaxy work.Not only do these changes greatly enhance the spectroscopic capabilities of the CSO, they will also enable the observatory to be integrated into the Harvard-Smithsonian Submillimeter Array (SMA), as an additional telescope.Keywords: Balanced mixer theory, continuous comparison receiver, radial probe, full-height waveguide to thinfilm microstrip transition, split-block, high current density superconducting-insulating-superconducting (SIS) tunnel junction, broad bandwidth quadrature waveguide hybrid, DC-break, IF match, Wilkinson in phase power combiner, Low noise amplfier (LNA), 4-8 GHz intermediate frequency (IF).

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“…The reasons for this, and the value of the optimum capacitance are discussed in these references [11,34]. The larger capacitance seems especially important when series arrays of SIS's are used [35].…”

Section: Sis Parasitic Capacitancementioning

confidence: 99%

“…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.…”

Section: Integrated Tuningmentioning

confidence: 99%

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Submillimeter-wave detection with superconducting tunnel diodes

Wengler

¹

1992

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Superconductor-Insulator-Superconductor (SIS) diodes are the detector elements in the most sensitive heterodyne receivers available from 100 to 500 GHz. SIS mixers are the front end of radio astronomical systems around the world. SIS mixer technology is being extended to 1 THz and higher frequencies for eventual use on spaceborne astronomical experiments.Here is a short review of submillimeter SIS mixers. The role of impedance matching in the proper design of an SIS mixer is described. A variety of methods for achieving good impedance match at submillimeter frequencies are presented. The experimental state of the submillimeter SIS jnixer art is described and summarized.

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“…Although a rectangular version of the "one-sided" probe has been used quite extensively by microwave engineers 22,23 and was introduced to the submillimeter community by Kerr et al 24 in 1990, it is fundamentally different from the proposed radial-shaped probe. The radial probe described here represents an attempt to extend the use of radial modes (known to give superior broad band performance in thin-film microstrip radial tuning stubs, as compared to rectangular stubs) to the microstrip to waveguide coupling problem.…”

mentioning

confidence: 99%

Heterodyne instrumentation upgrade at the Caltech Submillimeter Observatory

Kooi

¹

,

Kovács

²

,

Bumble

³

et al. 2004

Millimeter and Submillimeter Detectors for Astronomy II

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Balanced receivers are under development at the Caltech Submillimeter Observatory (CSO) for the 230/460 GHz and 345/660 GHz atmospheric windows. The mixers are tunerless, implemented in a balanced configuration, have a 4-8 GHz IF, and can be used in dual frequency observation mode. As shall be seen, the balanced arrangement provides a high level of amplitude noise immunity and allows all of the available LO power to be used. In turn, this permits complete automation of the receivers by means of synthesized LO source(s). A disadvantage of balanced mixers is, perhaps, that the sidebands at the IF remain convolved (DSB), unlike sideband separating (2SB) receivers. The latter, however are unbalanced and do not have the noise and LO injection advantages of balanced mixers. For the CSO, balanced mixers covering the range 180-720 GHz were judged most promising to facilitate many of the astrophysical science goals in the years to come.In parallel, a dual polarization 280-420 GHz continuous comparison (correlation) receiver is in an advanced state of development. The instrument has two beams on the sky; a reference and a signal beam. Using only cooled reflecting optics, two polarizing grids, and a quadrature hybrid coupler, the sky beams are coupled to four tunerless SIS mixers (both polarizations). The 4-12 GHz mixer IF outputs are, after amplification, correlated against each other. In principle, this technique results in flat baselines with very low RMS noise, and is especially well suited for high redshift Galaxy work.Not only do these changes greatly enhance the spectroscopic capabilities of the CSO, they will also enable the observatory to be integrated into the Harvard-Smithsonian Submillimeter Array (SMA), as an additional telescope.Keywords: Balanced mixer theory, continuous comparison receiver, radial probe, full-height waveguide to thinfilm microstrip transition, split-block, high current density superconducting-insulating-superconducting (SIS) tunnel junction, broad bandwidth quadrature waveguide hybrid, DC-break, IF match, Wilkinson in phase power combiner, Low noise amplfier (LNA), 4-8 GHz intermediate frequency (IF).

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Some recent developments in the design of SIS mixers

Cited by 74 publications

References 23 publications

Heterodyne Instrumentation Upgrade at the Caltech Submillimeter Observatory

Heterodyne Instrumentation Upgrade at the Caltech Submillimeter Observatory

Submillimeter-wave detection with superconducting tunnel diodes

Heterodyne instrumentation upgrade at the Caltech Submillimeter Observatory

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