JPL has measured and calibrated a WR2.2 waveguide wafer probe from GGB Industries in order to allow for measurement of circuits in the 325–500 GHz range. Circuits were measured, and one of the circuits exhibited 10 dB of gain at 475 GHz.
The MMIC circuit was fabricated at Northrop Grumman Corp. (NGC) as part of a NASA Innovative Partnerships Program, using NGC’s 35-nm-gate-length InP HEMT process technology. The chip utilizes three stages of HEMT amplifiers, each having two gate fingers of 10 μm in width. The circuits use grounded coplanar waveguide topology on a 50-μm-thick substrate with through substrate vias. Broadband matching is achieved with coplanar waveguide transmission lines, on-chip capacitors, and open stubs. When tested with wafer probing, the chip exhibited 10 dB of gain at 475 GHz, with over 9 dB of gain from 445–490 GHz.
Low-noise amplifiers in the 400–500 GHz range are useful for astrophysics receivers and earth science remote sensing instruments. In particular, molecular lines in the 400–500 GHz range include the CO 4-3 line at 460 GHz, and the CI fine structure line at 492 GHz. Future astrophysics heterodyne instruments could make use of high-gain, low-noise amplifiers such as the one described here. In addition, earth science remote sensing instruments could also make use of low-noise receivers with MMIC amplifier front ends.
Present receiver technology typically employs mixers for frequency down-conversion in the 400–500 GHz band. Commercially available mixers have typical conversion loss in the range of 7–10 dB with noise figure of 1,000 K. A low-noise amplifier placed in front of such a mixer would have 10 dB of gain and lower noise figure, particularly if cooled to low temperature. Future work will involve measuring the noise figure of this amplifier.
This work was done by Lorene A. Samoska, King Man Fung, David M. Pukala, and Pekka P. Kangaslahti of Caltech; and Richard Lai and Linda Ferreira of Northrup Grumman Corp. for NASA’s Jet Propulsion Laboratory. NPO-47541
This Brief includes a Technical Support Package (TSP).
On-Wafer Measurement of a Multi-Stage MMIC Amplifier With 10 dB of Gain at 475 GHz
(reference NPO-47541) is currently available for download from the TSP library.
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Overview
The document is a Technical Support Package from NASA's Jet Propulsion Laboratory (JPL) detailing advancements in the measurement and development of multi-stage MMIC (Monolithic Microwave Integrated Circuit) amplifiers, particularly focusing on a specific amplifier that achieves a gain of 10 dB at a frequency of 475 GHz. This work is part of a broader initiative aimed at enhancing the performance of coherent detectors used in various scientific applications, including radiometry, polarimetry, and high-resolution spectroscopy.
The project aims to achieve near-quantum-limited performance in the basic building blocks of massive arrays of coherent detectors across frequency ranges of 70–280 GHz. Specific performance goals are set for different frequency bands, targeting noise performance levels significantly below the current state of the art. For instance, the goals include achieving noise performance of less than 3 times the quantum limit (3q) in the 70–118 GHz range, less than 5q in the 120–160 GHz range, and less than 10q in the 180–280 GHz range. These advancements are crucial for applications in cosmic microwave background (CMB) polarization studies and atmospheric chemistry.
The document also discusses the technical aspects of the measurement process, including the use of cryogenic wafer probing techniques to assess the performance of low-noise amplifiers (LNAs) at various frequencies. Notably, it highlights the achievement of a system noise temperature of 30K at 90 GHz and as low as 12K at 38 GHz for Q-band LNAs, marking significant milestones in cryogenic measurement capabilities.
Figures included in the document illustrate various setups, such as the cryogenic probe station used for testing, and provide data on the performance of different amplifier configurations. The document acknowledges contributions from various researchers and institutions involved in the project, emphasizing collaborative efforts in advancing microwave technology.
Overall, this Technical Support Package serves as a comprehensive overview of the ongoing research and development efforts at JPL to enhance the performance of MMIC amplifiers, which are vital for future scientific missions and applications in astrophysics and Earth science. The findings and methodologies presented are expected to have significant implications for both technological advancements and scientific discoveries.
