Broadband MMIC LNAs for ALMA Band 2+3 With Noise Temperature Below 28 K

Abstract

Recent advancements in transistor technology, such as the 35 nm InP HEMT, allow for the development of monolithic microwave integrated circuit (MMIC) low noise amplifiers (LNAs) with performance properties that challenge the hegemony of SIS mixers as leading radio astronomy detectors at frequencies as high as 116 GHz. In particular, for the Atacama Large Millimeter and Submillimeter Array (ALMA), this technical advancement allows the combination of two previously defined bands, 2 (67-90 GHz) and 3 (84-116 GHz), into a single ultra-broadband 2+3 (67-116 GHz) receiver. With this purpose, we present the design, implementation, and characterization of LNAs suitable for operation in this new ALMA band 2+3, and also a different set of LNAs for ALMA band 2. The best LNAs reported here show a noise temperature less than 250 K from 72 to 104 GHz at room temperature, and less than 28 K from 70 to 110 GHz at cryogenic ambient temperature of 20 K. To the best knowledge of the authors, this is the lowest wideband noise ever published in the 70-110 GHz frequency range, typically designated as W-band.

Celestial Signals: Are Low-Noise Amplifiers the Future for Millimeter-Wave Radio Astronomy Receivers?

“…The complexity of designing an ultra-wideband embedding circuit is due to the difficulty of matching this broad range of impedances to the input impedance of the MMIC, typically of the order of 50 Ω. Examples of W-band LNAs with more than 40% RF bandwidth are shown in [12] and [23], and 50% in [21].…”

Characterization of self-heating in cryogenic high electron mobility transistors using Schottky thermometry

“…Microwave low noise amplifiers (LNAs) based on high electron mobility transistors (HEMTs) are widely-used components of scientific instrumentation in fields such as radio astronomy [1,2], deep space communication [3], and quantum computing [4][5][6][7][8]. After decades of development [9][10][11][12][13],…”

Optimization of spaceflight millimeter-wave impedance matching networks using laser trimming

“…This is usually achieved through the application of a waveguide-to-microstrip (WG-MS) transition that transforms the impedance of the waveguide channel to the optimal conjugate impedance of the MMIC input or output port. At millimeter wavelengths, the WG-MS transition is typically fabricated from a thin film gold conductive layer, ∼3 μm in thickness, which is deposited onto a thin, <100 μm, quartz or alumina substrate and then suitably patterned to form a sequence of distributed elements [1][2][3].…”

“…Using WG-MS transitions at frequencies higher than 100 GHz presents three particular challenges: (1) due to the uncertainties in pre-packaging on-wafer probing, it is often difficult to determine precisely the optimal impedance required by the MMIC [4,5]; (2) simulating the interaction between the MMIC and the WG-MS transition is highly complex and thus prone to error; (3) once installed, the fabricated transition cannot be tuned in order to optimize the device packaged performance, i.e. to correct for the errors that may arise from 1 and 2.…”