Abstract-New developments for integrated Schottky receivers in the terahertz regime (Conference Presentation)

Jonathan Hoh,  Christopher Groppi,  Jose V. Siles,  Robert H. Lin,  Philip Mauskopf, Choonsup Lee,  Phil Putman,  Adrian J. Tang,

https://www.spiedigitallibrary.org/conference-proceedings-of-spie/10708/1070817/New-developments-for-integrated-Schottky-receivers-in-the-terahertz-regime/10.1117/12.2312927.short?SSO=1

Recent advances in small satellite technology now allow us to consider their use for astrophysics and other remote sensing applications. One wavelength regime of intense interest to astrophysics is the terahertz portion of the electromagnetic spectrum as this is where water vapor and molecular oxygen lie. Water lines at 557 GHz and the 1100-1200 GHz band are excellent diagnostics of water vapor in the interstellar medium, the Earth’s atmosphere and the atmospheres of other planetary bodies. Here we present the preliminary results of a low-mass, low-power highly integrated Schottky diode based coherent receiver system suitable for deployment on cubesats or other small satellite platforms. The current state of the art coherent Schottky receivers are too large to consider deploying on any smaller form of space-based satellite. Using novel packaging methods, we have taken already existing cutting-edge modular 520-600 GHz receivers and packaged them into an integrated system with a volume and power consumption significantly smaller than the state of the art. We also present the designs of a similar integrated receiver for the first excited state of water vapor operating at the 1040-1200 GHz range. Further research will be spent exploring whether we can use passively cooling technologies to better enhance the performance of these Schottky receivers.

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Probes Promise Precise On-Wafer Measurements At THz Frequencies

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Terahertz-frequency integrated circuits (ICs) offer tremendous promise in terms of available bandwidth for short-range communications. Although such devices have been fabricated for use at frequencies through 3000 GHz (3 THz), the on-wafer commercial probes for characterizing these high-frequency ICs are limited to about 340 GHz. As a solution, Theodore J. Reck, Lihan Chen, Chunhu Zhang, Alex Arsenovic, Christopher Groppi, Arthur W. Lichtenberger, Robert M. Weikle II, and N. Scott Barker—who combined their talents from the University of Virginia and Arizona State University—have presented a scalable approach to the fabrication of high-frequency wafer probes that integrates a rectangular-waveguide probe and coplanar-waveguide (CPW) wafer probe onto a single silicon chip. The wafer probes feature a ground-signal-ground (GSG) configuration on a 15-micron-thick silicon substrate.
The experimental probe consists of an E-plane split waveguide block that houses the silicon chip. Tabs of silicon electroplated with gold are clamped between the two halves of the block, both for mechanical support and alignment of the housing. The probe chip couples from rectangular waveguide through a radial E-plane waveguide probe into a transmission-line channel. This channel emerges from the block where the signal mode is converted to the GSG wafer probe.
To verify that the design was capable of providing sufficient force to achieve a low-resistance contact with an IC under test, a probe with a single tip was fabricated and evaluated with different contact forces. A contact resistance of 0.07 Ω was achieved for a contact force of 1 mN. See “Micromachined Probes for Submillimeter-Wave On-Wafer Measurements—Part 1: Mechanical Design and Characterization” and “Part 2: RF Design and Characterization,” IEEE Transactions on Terahertz Science and Technology, November 2011, pp. 349 and 357.