Noise temperature is lower than in the prior state of the art.
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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
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. NPO-45178