A three-stage monolithic millimeter-wave integrated-circuit (MMIC) amplifier designed to exhibit low noise in operation at frequencies from about 100 to somewhat above 180 GHz has been built and tested. This is a prototype of broadband amplifiers that have potential utility in diverse applications, including measurement of atmospheric temperature and humidity and millimeter-wave imaging for inspecting contents of opaque containers.

Figure 1. This MMIC Amplifier includes InP high-electron-mobility transistors (HEMTs) connected to microstrip transmission lines on a substrate of 2-mil (≈51-μm) thickness. Each HEMT has two fingers and a gate width of 15 μm, for a total gate periphery of 30 μm.
Figure 2. These Plots of Performance Data were derived from measurements on the amplifier as packaged in a WR-05 waveguide [a waveguide having a cross section of 0.0510 by 0.0255 in. (about 1.30 by 0.65 mm), nominally for the frequency range of 140 to 220 GHz].
Figure 1 depicts the amplifier as it appears before packaging. Figure 2 presents data from measurements of the performance of the amplifier as packaged in a WR-05 waveguide and tested in the frequency range from about 150 to about 190 GHz. The amplifier exhibited substantial gain throughout this frequency range. Especially notable is the fact that at 165 GHz, the noise figure was found to be 3.7 dB, and the noise temperature was found to be 370 K: This is less than half the noise temperature of the prior state of the art.

This work was done by Pekka Kangaslahti, David Pukala, King Man Fung, and Todd Gaier of Caltech and Xiaobing Mei, Richard Lai, and William Deal of Northrop Grumman Corporation for NASA’s Jet Propulsion Laboratory. For more information, contact This email address is being protected from spambots. You need JavaScript enabled to view it.. NPO-45178

Topics:
Amplifiers Electric power grid Electronic equipment Humidity Imaging and visualization Logistics Materials handling Noise Optics Packaging Semiconductors & ICs Transistors Weather and climate
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This article first appeared in the August, 2009 issue of NASA Tech Briefs Magazine (Vol. 33 No. 8).

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