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In this paper we report ultra-low-noise amplifier modules and amplifier module chains for V-band (50-75 GHz). The amplifier chips were fabricated in Northrop Grumman Corporation's (NGC) 35-nm InP HEMT technology and packaged in WR15 waveguide housings utilizing alumina E-plane waveguide probes. The amplifier modules achieve 18 to 27 K noise temperatures from 50 to 75 GHz when cryogenically cooled to 21 K. When measured through a mylar vacuum window, a cascade of two amplifier modules achieves a receiver noise temperature of 18.5 K at 58 GHz. A second chain has a measured receiver noise temperature between 20 to 28 K for the whole V-band. To the best of authors' knowledge, these are the lowest LNA noise temperatures for V-Band reported to date.

Indium Phosphide MMIC LNAs are enabling new capabilities in instrument development. The development of arrays of hundreds of cryogenically-cooled millimeter wave receivers has previously been challenging, but is now achievable with highly repeatable MMIC processes and advances in cryogenic on-wafer testing of LNAs. We have developed InP HEMT LNA MMICs for the 67–90 GHz frequency band that is the last missing receiver system from the ALMA. These MMICs provided average performance of less than 22.5 K noise temperature over the frequency band and minimum noise temperature of 17.5 K at 72 GHz. These LNAs achieve NT=220K (NF=2.4dB) at 90 GHz for Earth remote sensing instrument on Sentinel-6. Our HRMR (High Resolution Microwave Radiometer) achieves NEDT < 0.05K enabling Sentinel-6 to measure coastal ocean topography at 3 km resolution with better than 1 cm accuracy.

We report the first ever terahertz monolithic integrated circuit amplifier based on 25-nm InP high electron mobility transistor (HEMT) process demonstrating amplification at 1 THz (1000 GHz) with 9-dB measured gain at 1 THz. This milestone was achieved with a 25-nm InP HEMT transistor, which exhibits 3.5-dB maximum available gain at 1 and 1.5 THz projected $f_{\mathrm {\mathbf {MAX}}}$ .

In this letter we report an ultra-low-noise amplifier module chain in the WR4 frequency range. The amplifier chips were fabricated in a 35 nm InP HEMT technology and packaged in waveguide housings utilizing quartz E-plane waveguide probes. When cryogenically cooled to 22 K and measured through a mylar vacuum window, the amplifier module chain achieves a receiver noise temperature of 87 K at 228 GHz and less than a 100 K noise temperature from 217 to 236 GHz. The LNA modules have 21–31 dB gain and the power dissipation is 12.4–15.8 mW. To the best of authors' knowledge, these are the lowest LNA noise temperatures at these frequencies reported to date.

The noise models of InP and GaAs HEMTs are compared with measurements at both 300 and 20 K. The critical parameter, Tdrain, in the Pospieszalski noise model is determined as a function of drain current by measurements of the 1-GHz noise of discrete transistors with 50- Ω generator impedance. The dc I-V for the transistors under test are presented and effects of impact-ionization are noted. InP devices with both 100% and 75% indium mole fraction in channel are included. Examples of the design and measurement of very wideband low-noise amplifiers (LNAs) using the tested transistors are presented. At 20-K physical temperature the GaAs LNA achieves 10-K noise over the 0.7-16-GHz range with 16 mW of power and an InP LNA measures 20-K noise over the 6-50-GHz range with 30 mW of power.

This letter reports on the demonstration of a transceiver operating from 190 to 200 GHz. The system is assembled using splitblock waveguide integrated microwave assemblies, with MMICs realized using advanced InP HEMTs with sub-50 nm gate lengths. Across the band a receiver noise figure 6 dB and transmitter output power >20 dBm have been demonstrated. A table top link demonstrated successful QPSK and QAM modulation and demodulation using a 196 GHz carrier wave. Filtering was built into the system to ensure low in-band spurious response.

This paper reports on the first demonstration of a micro-integrated pixel operating in the sub-millimeter-wave regime. The pixel consists of a low-noise amplifier realized in InP HEMT, an nIN diode detector, and micromachined horn antenna. The monolithic microwave integrated circuits are attached inside a micromachined silicon waveguide through a novel solder ball process, and a micromachined horn antenna caps the waveguide, which completes the pixel. The form factor is > 2500 × reduction from traditional waveguide block packaging. This size reduction, high level of integration, and integration with a horn antenna enables this technology to be scalable to compact 2-D arrays in the sub-millimeter-wave regime. The pixel noise temperature is measured to be ~5400 K, which corresponds to sensitivity of an ideal total-power radiometer (ΔTM) of ~0.21 K given a 30-ms integration time and bandwidth of 20 GHz.

In this work, we describe monolithic millimeter-wave integrated circuit (MMIC) Low Noise Amplifier (LNA) and mixer designs for U-Band, also known as the WR19 waveguide band (40–60 GHz). The LNAs were fabricated in NGC's 35 nm InP HEMT MMIC process. The MMICs were packaged in WR19 waveguide housings and tested for noise, both at room temperature and cryogenically. We present the results, including a comparison to the state-of-the-art, and discuss applications for amplifiers in this frequency range. To date, these are the first cryogenic 35 nm InP MMIC results covering the 40–60 GHz range. We achieved a noise temperature less than 30 K over the 40–60 GHz range, when the amplifiers were cryogenically cooled. These results are comparable with other results in the literature, and we believe are the lowest reported for MMICs in the 50–60 GHz range.

We have developed V-Band (50–75 GHz) monolithic millimeter-wave integrated circuit (MMIC) low noise amplifiers using NGC's 35 nm InP HEMT technology. The MMIC LNAs exhibit noise temperatures of 150–270K over the full waveguide band. Subharmonic MMIC mixers were also developed using United Monolithic Semiconductor's GaAs Schottky diode process, and cover V-band with 15–21 dB conversion loss. These components form the front end of receivers that could be used for radio astronomy. While much of V-Band is opaque to the atmosphere, a future space probe to map the intensity of carbon monoxide (CO) in V-band would help astronomers understand the early universe.

This paper presents a 90–100 GHz heterodyne radiometer module based on a CMOS receiver system-on-chip (SoC). The SoC contains a frequency synthesizer, downconverter, RF&IF amplification, as well as a wide range of auto-leveling and calibration, and LO stabilization functions. To provide low-noise operation the CMOS SoC is packaged within a waveguide block and mated with an InP MMIC based LNA pre-amplifier. The complete module delivers noise performance below 400°K and is capable of less than 0.5K NEΔT with an integration time of 50 ms. The entire radiometer instrument consumes 257mW of power and weighs only 334 grams.

Due to copyright restrictions, the access to the full text of this article is only available via subscription. In this paper we discuss the design of low-noise amplifiers (LNAs) for both cryogenic and room-temperature operation in general and take the stability and linearity of the amplifiers into special consideration. Oscillations that can occur within a multi-finger transistor are studied and verified with simulations and measurements. To overcome the stability problem related to the multi-finger transistor design approach a parallel two-finger unit transistor monolithic microwave integrated circuit LNA design technique, which enables the design of wideband and high-linearity LNAs with very stable, predictable, and repeatable operation, is proposed. The feasibility of the proposed design technique is proved by demonstrating a three-stage LNA packaged in a WR10 waveguide housing and fabricated using a 35-nm InP HEMT technology that achieves more than a 20-dB gain from 75 to 116 GHz and 26-33-K noise temperature from 85 to 116 GHz when cryogenically cooled to 27 K. Jet Propulsion Laboratory, California Institute of Technology ; Oak Ridge Associated Universities under NASA Postdoctoral Program (NPP) ; Academy of Finland ; Alfred Kordel Foundation ; National Aeronautics and Space Administration

In this work, we describe new miniaturized low noise amplifier modules which we developed for incorporation in small-scale satellites or Cubesats, and which exhibit similar or better performance compared to previously reported LNAs in the literature. We have targeted the WR4 (170–260 GHz) and WR3 (220–325 GHz) waveguide bands for the module development. The modules include two different methods of E-plane probes which have been developed for low loss, and stability at high frequencies. MMIC LNAs were also developed for these frequency ranges and fabricated in Northrop Grumman Corporation's 35 nm InP HEMT technology, and we have experimentally verified that noise performance is lower than reported in prior work. The best results include a miniature LNA module with 550K noise at 224 GHz, and a wideband LNA module with 15 dB gain from 230–280 GHz.

This paper reports on several solid-state power amplifier (PA) modules operating at frequencies around the 220-GHz propagation window. Included is a single module demonstrating saturated output power ≥60 mW from 205 to 225 GHz and peak output power of 75 mW at 210 GHz using eight-way on-chip power combining. The output power is further increased by using waveguide power combining with WR-4 waveguide. Results include a single two-way combined module achieving >; 100 mW of power from 210 to 225 GHz and four-way combining using two two-way combiners to reach 185 mW of output power at 210 GHz. The amplifier MMICs uses sub-50-nm InP HEMT transistors, coplanar waveguide (CPW) technology, and on-chip electromagnetic transitions to waveguide. Finally, preliminary burn-in and initial room-temperature lifetest data is shown.

At Terahertz (THz) frequencies, passive space-borne Earth exploration services may be interfered by upcoming active communication applications. Aiming for coexistent use of the THz band by both active and passive applications, this paper identifies critical scenarios where interference can possibly occur. Atmospheric attenuation simulations are used along with appropriate propagation models to account for correct scenario-specific wave propagation conditions. Furthermore, distance-dependent measurements of the path loss are taken at 300 GHz. The atmospheric attenuation and propagation models are then employed in order to simulate possible interference powers for the individual reference scenarios under worst case-conditions. Based on existing data for the maximum allowed interference, guidelines for appropriate system specifications of active THz hardware (e.g., transmit power constraints) are developed and achievable system performances are evaluated. Countermeasures against potential interference are discussed. Thus, any interference can be anticipated and compensated for already in the early design phase of THz communication systems.

In this paper, progress toward developing solid-state power-amplifier modules at 0.65 THz is reported. This work is enabled by a >;1 THz fMAX InP HEMT transistor with a 30-nm gate and an integrated circuit process specifically tailored for circuits operating at frequencies approaching 1 THz. The building block of the reported amplifier modules is an eight-stage terahertz monolithic integrated circuit (TMIC) amplifier. The first six stages of the TMIC use 20- transistors, while the final two output stages rely on two power-combined 20-μm transistors to increase the output power. For operation at 0.65 THz, the TMIC also relies on integrated electromagnetic transitions for direct coupling with the WR1.5 waveguide of the amplifier package. Two modules are reported, with the first module containing a single TMIC and demonstrating a peak saturated output power of 1.7 mW at 640 GHz with a measured small-signal gain ≥10 dB from 629 to 638 GHz. The second module features two power-combined TMICs to increase output power. This is done using a waveguide Y-junction as both the combiner and splitter. In test, this power-combined module reached a peak output power of 3 mW at 650 GHz and measured small-signal gain ≥10 dB from 625 to 640 GHz.

In this paper, background describing THz monolithic integrated circuits using InP HEMT is presented. This three-terminal transistor technology has been used to realize amplifiers, mixers, and multipliers operating at 670 GHz. Transistor and processing technology, packaging technology, and circuit results at 670 GHz are described. The paper concludes with initial results from a 670-GHz InP HEMT receiver and trends for InP HEMT components.

Pivotal in the design of circuits is the ability to efficiently translate available transistor gain to high gain per stage. Remarkably, for 35-nm InP HEMT transistors, the efficiency of this translation remains high even up to ~0.5 THz. The ever shrinking wavelength correlated with higher frequencies necessitates a scaling of not only the device layout, but also of the passive elements and wafer thickness. Furthermore, to avoid distributed effects, the length of transistor gate fingers must be reduced.

We use quantum wires fabricated on undoped GaAs/AlGaAs heterostructures in which the average impurity separation is greater than the device size to compare the behaviour of the zero-bias anomaly against predictions from Kondo and spin polarisation models. Cleanliness and reproducibility are significantly improved in our undoped devices when compared to our doped devices.

Fully Undoped Heterostructures, by means of being an extremely clean system, are ideal for studying transport in mesoscopic regions at ultra-low densities. At low temperatures, effects in two and one dimensions are seen which cannot be explained within the framework of non-interacting particles. The insight offered by induced devices highlights the aspects of theories which require modification to fully explain the physics of these complex regions and effects. © The Electrochemical Society.

S. Sarkozy, K. Das Gupta, F. Sfigakis, I. Farrer, H. Beere, R. Harrell, D. Ritchie, G. Jones Cavendish Laboratory, University of Cambridge, Cambridge, CB3 0HE, UK Undoped GaAs/AlGaAs heterostructures are attractive systems for studying lower dimensional structures and electron-electron interactions, eliminating or reducing many of the problems that come with the more traditional modulation doped system. A major obstacle involved in using systems where the two dimensional electron gas (2DEG) was induced with a biased top gate was the inability to form a reliable ohmic contact to the 2DEG. We report here a systematic study of the contact system (Au-Ge-Ni), including a discussion of how a various diffusion barriers may prove beneficial, and how the etch depth of the recessed ohmic contact effects the window of success. Yield with the new process approaches 100%, compared to a catastrophically low rate before the system was understood.

In this paper we propose a parallel two-finger unit transistor MMIC low-noise amplifier design technique which enables the design of wideband and high linearity low-noise amplifiers with very stable, predictable, and repeatable operation. We prove the feasibility of the proposed design technique by demonstrating a three-stage LNA packaged in a WR10 waveguide housing and fabricated using a 35-nm InP HEMT technology that achieves more than a 20-dB gain from 75 to 116 GHz and 26–33-K noise temperature from 85 to 116 GHz when cryogenically cooled to 27 K.

In this letter, low noise amplification at 0.67 THz is demonstrated for the first time. A packaged InP High Electron Mobility Transistor (HEMT) amplifier is reported to achieve a noise figure of 13 dB with an associated gain greater than 7 dB at 670 GHz using a high fMAX InP HEMT transistors in a 5 stage coplanar waveguide integrated circuit. A 10-stage version is also reported to reach a peak gain of 30 dB. These results indicate that InP HEMT integrated circuits can be useful at frequencies approaching a terahertz.

In this paper, we demonstrate non-destructive cryogenic probing of monolithic microwave integrated circuit (MMIC) amplifiers at W-band and discuss the implications for the development of large-format focal plane arrays for radio astronomy. Using a purpose-built cryogenic probe station to measure S-parameters and noise temperature of MMIC low-noise amplifiers (LNAs), an order of magnitude increase in efficiency can be achieved when compared with measurements on individually packaged amplifiers. The amplifiers are tested non-destructively, which enables selection based on cryogenic noise and gain; this is crucial for the development of highly-integrated miniaturized receivers for focal plane arrays, such as those used for the measurement of the cosmic microwave background (CMB) polarization and future arrays aimed at probing the epoch of reionization (EoR).

In this work, we report on developments toward ultra-low noise amplifier modules for the WR4 frequency range, covering 170-260 GHz. The amplifiers in question utilize 35 nm HEMT transistors on a 50 μm thick InP substrate, and were developed at NGC. While recent work in this frequency band has demonstrated the usefulness and advanced technology of utilizing integrated waveguide transitions fabricated on the high dielectric constant MMIC amplifiers themselves, we present evidence here that more standard, cost effective techniques like merging low-loss quartz probes with short wire bonds can provide excellent noise performance, even at these high frequencies. The amplifiers discussed in this paper demonstrate a record 600K noise (4.8 dB) at 220 GHz and 700K (5.2 dB) noise at 240 GHz.

In this letter, we present an amplifier module operating at a frequency of 0.48 THz. This represents almost a 50% increase in solid-state amplifier operating frequency compared to prior state of the art, and is the highest reported amplifier to date. The amplifier demonstrates a peak gain of 11.7 dB measured in a waveguide split-block housing. Sub 50-nm InP HEMT transistors with an estimated f MAX > 1 THz are used to achieve this level of performance. The five stage amplifier is realized in coplanar waveguide, and uses monolithically integrated dipole probes to couple the chip from the WR 2.2 waveguide.

We report S-parameter and noise measurements for three different InP 35 nm gate-length High Electron Mobility Transistor (HEMT) Low Noise Amplifier (LNA) designs operating in the frequency range centered on 140 GHz. When packaged in a WR-6.1 waveguide housing, the LNAs have an average measured noise figure of 3.0 dB-3.6 dB over the 122-170 GHz band. One LNA was cooled to 20 K and a record low noise temperature of 46 K, or 0.64 dB noise figure, was measured at 152 GHz. These amplifiers can be used to develop receivers for instruments that operate in the 130-170 GHz atmospheric window, which is an important frequency band for ground-based astronomy and millimeter-wave imaging applications.

In this paper we present the design and measurement results, both on-wafer and in package, of an ultra-low-noise and wideband monolithic microwave integrated circuit (MMIC) amplifier in the frequency range of 75 to 116 GHz. The three-stage amplifier packaged in a WR10 waveguide housing and fabricated using a 35-nm InP HEMT technology achieves a record noise temperature of 23 K at 108 GHz when cryogenically cooled to 27 K. The measured gain is 22 to 27 dB for frequency range of 75 to 116 GHz. Furthermore, the amplifier utilizes four-finger devices with a total gate width of 60 μm resulting in higher output power. Therefore, we consider that this amplifier achieves state-of-the-art performance in terms of bandwidth, noise temperature, gain, and linearity so far reported for cryogenically cooled amplifiers around W-band.

This paper reports on the process and technology of the sub-50nm InP HEMT MMIC process which has enabled signal amplification up to 670 GHz. In particular, considerations not commonly addressed such as the related processing requirements and uniformity of transistors to establish working chipsets are discussed. Finally, initial burn in data is presented as the technology evolves from a research and development process to production.

We present two low-noise amplifiers for the frequency range of 160 to 270 GHz. The amplifiers were fabricated using a 35-nm InP HEMT technology and designed for room temperature and cryogenic operation. A four-stage amplifier in a common-source topology and a three-stage amplifier utilizing a cascode stage at the output achieve 15 to 25-dB on-wafer measured gain from 160 to 270 GHz. When packaged in WR5 waveguide housings the amplifiers exhibit room temperature measured noise of 600 to 760 K from 160 to 220 GHz. When cryogenically cooled the three-stage amplifier shows a noise of 80 to 115 K over the range of 164 to 220 GHz. Furthermore, our initial room temperature measurements show a noise figure of 7-8 dB over the 220 to 252 GHz range for a four-stage amplifier packaged in a WR3 waveguide housing.

Over the last few years, operating frequencies of InP HEMT Transistors have pushed above 100 GHz (1 THz). This has allowed electronic circuitry to be realized at frequencies as high as 670 GHz. In particular, Low Noise Amplifiers (LNA), Power Amplifiers (PA), mixers and multipliers have all been implemented. A result of this has been integrated circuit receivers and transmitters operating to frequencies as high as 670 GHz.

In this paper, we describe two monolithic millimeter-wave integrated circuit (MMIC) low noise amplifiers (LNAs) for W-Band which have a noise temperature of 30K or better over a wide bandwidth when cryogenically cooled. The LNAs were designed and fabricated in NGC's InP HEMT MMIC process having 35 nm gate length and employing an InAs Composite Channel (IACC). A two-stage amplifier exhibits room temperature S21 gain of 15–18 dB, and cryogenic gain of 20 dB with minimum noise temperature of 25K at 95 GHz, and less than 40K noise temperature between 75–105 GHz. A three-stage amplifier exhibits 29 dB of S21 gain, and a cryogenic noise temperature below 30K over the range of 94–109 GHz. We discuss the design of the amplifiers, measured and simulated S-parameters, and cryogenic measurements. To our knowledge, these are the highest frequency and lowest noise temperatures ever reported for InP cryogenic LNAs covering W-Band.

We present noise temperature and gain measurements of a W-band heterodyne module populated with MMIC LNAs designed and fabricated using a 35 nm InP HEMT process. The module has a WR-10 waveguide input. GPPO connectors are used for the LO input and the I and Q IF outputs. The module is tested at both ambient (300 K) and cryogenic (25 K) temperatures. At 25 K physical temperature, the module has a noise temperature in the range of 27–45 K over the frequency band of 75–111 GHz. The module gain varies between 15 dB and 27 dB. The band-averaged module noise temperature of 350 K and 33 K were measured over 80–110 GHz for the physical temperature of 300 K and 25 K, respectively. The resulting cooling factor is 10.6.

In this paper, a 210 GHz solid-state power amplifier (SSPA) module is presented. The amplifier MMIC uses sub-50 nm InP HEMT transistors, coplanar waveguide (CPW) technology, and on-chip electromagnetic transitions to waveguide. Two levels of power combining were used on-chip to achieve total transistor output periphery of 0.96 mm. The first level is a 1:4 CPW Dolph-Chebychev transformer. The second level is a two-way, novel dual transition to the waveguide. In this method, two amplifiers were placed on the MMIC die, each with independent transition to the waveguide, where their output power is combined. This method reduced the combining loss compared to traditional coupler methods. The SSPA module demonstrated saturated output power iY 60 mW from 205 to 225 GHz and peak output power of 75 mW at 210 GHz, representing a significant increase in SSPA output power at these frequencies compared to the prior state-of-the-art.

In this paper, we describe the design, simulation, and on-wafer measurements of Submillimeter-wave Monolithic Integrated Circuit (S-MMIC) amplifiers having gain in the 400–500 GHz range. A single-stage amplifier and two three-stage amplifiers with similar topology are presented, and have been fabricated in Northrop Grumman Corporation's (NGC) 35-nm InP high electron mobility transistor (HEMT) process. The circuits were fabricated using different indium channel compositions on different wafers, and comparison of the results based on the indium content will be presented. We have performed on-wafer S-parameter calibration and measurements using newly developed WR2.2 waveguide wafer probes from 325–508 GHz. We measured approximately 5 dB of gain for the single stage amplifier at 437 GHz, and approximately 10 dB of gain at 474 GHz for a three-stage amplifier, with over 9 dB of gain at 490 GHz.

Broadband sub-millimeter wave technology has received significant attention for potential applications in security, medical, and military imaging. Despite theoretical advantages of reduced size, weight, and power compared to current millimeter-wave systems, sub-millimeter-wave systems are hampered by a fundamental lack of amplification with sufficient gain and noise figure properties. We report on the development of a sub-millimeter wave amplifier module as part of a broadband pixel operating from 300-350 GHz, biased off of a single 2V power supply. Over this frequency range, > 38 dB gain and < 8.3 dB noise figure are obtained and represent the current state-of-art performance capabilities. The prototype pixel chain consists of two WR3 waveguide amplifier blocks, and a horn antenna and diode detector. The low noise amplifier Sub-Millimeter-wave Monolithic Integrated Circuit (SMMIC) was originally developed under the DARPA SWIFT and THz Electronics programs and is based on sub 50 nm Indium Arsenide Composite Channel (IACC) transistor technology with a projected maximum oscillation frequency f max > 1.0 THz. This development and demonstration may bring to life future sub-millimeter-wave and THz applications such as solutions to brown-out problems, ultra-high bandwidth satellite communication cross-links, and future planetary exploration missions.

In this paper, we demonstrate that the cascode amplifier topology can be extended to operating frequencies > 500 GHz. Two packaged cascode amplifiers are reported, including a broadband 3 stage amplifier with ~17 dB gain and 8.3 dB packaged noise figure at 300 GHz and a narrowband amplifier with 10 dB gain at 0.55 THz measured in package. Both of these amplifiers use 30 nm InP HEMT transistors, are realized in coplanar waveguide on a 1-Mil thick InP substrate and use a monolithically integrated electromagnetic transition for coupling energy from the chip to the waveguide package.

This paper will review the progress of HEMT MMW MMIC technologies developed at Northrop Grumman Aerospace Systems for radiometer sensor applications. Specific HEMT MMIC functions that have been developed for the radiometer front-end include the RF LNA, IF LNA and LO driver power amplifiers. We report recent advancements in room and cryogenically operated InP HEMT low noise amplifiers and power amplifiers operating from 1 GHz to 300 GHz and discuss past and present system applications of these MMICs.

In this paper, we report recent advances on sub-50 nm InP HEMT have achieved new benchmarks of 586 GHz fT and 7 dB amplifier circuit gain at 390 GHz

In this paper, a 220 GHz solid-state power amplifier (SSPA) module is presented. Eight-way on-chip power combining is used to achieve a saturated output power ≥ 50 mW over a 217.5 to 220 GHz bandwidth, representing a significant increase in SSPA output power at this frequency compared to prior state of the art. The amplifier MMIC is implemented in coplanar waveguide (CPW) technology and uses sub 50 nm InP HEMT transistors. Two levels of power combining, a 2∶1 tandem coupler and a 4∶1 Dolph-Chebychev transformer, are realized in CPW. The module demonstrates ≥ 11.5 dB small signal gain from 207 to 230 GHz. Saturated output power ≥ 40 mW was measured from 216 to 222.5 GHz.

In this paper, we present the latest advancements of active sub-MMW integrated circuits (S-MMIC) based on 35 nm InP HEMT technology. The current state-of-the-art results include the first demonstrated LNA, PA and fundamental oscillator modules above 300 GHz.

We use quantum wires fabricated on undoped GaAs/AlGaAs heterostructures in which the average impurity separation is greater than the device size to compare the behavior of the zero-bias anomaly against predictions from Kondo and spin-polarization models. Both theories display shortcomings, the most dramatic of which is the linear electron-density dependence of the zero-bias anomaly spin splitting at fixed magnetic field $B$ and the suppression of the Zeeman effect at pinch off.

Using high quality undoped GaAs/AlGaAs heterostructures with optically patterned insulation between two layers of gates, it is possible to investigate very low density mesoscopic regions where the number of impurities is well quantified. Signature appearances of the scattering length scale arise in confined two dimensional regions, where the zero-bias anomaly (ZBA) is also observed. These results explicitly outline the molecular beam epitaxy growth parameters necessary to obtain ultra low density large two dimensional regions as well as clean reproducible mesoscopic devices., 4 pages, 4 EPS figs

Broadband sub-millimeter wave technology has received significant attention for potential applications in security, medical, and military imaging. Despite theoretical advantages of reduced size, weight, and power compared to current millimeter wave systems, sub-millimeter wave systems have been hampered by a fundamental lack of amplification with sufficient gain and noise figure properties. We report a broadband pixel operating from 300 to 340 GHz, biased off a single 2 V power supply. Over this frequency range, the amplifiers provide > 40 dB gain and 1.0 THz. The first sub-millimeter wave-based images using active amplification are demonstrated as part of the Joint Improvised Explosive Device Defeat Organization Longe Range Personnel Imager Program. This development and demonstration may bring to life future sub-millimeter-wave and THz applications such as solutions to brownout problems, ultra-high bandwidth satellite communication cross-links, and future planetary exploration missions.