Paul Janke

AlGaN/GaN heterojunction field effect transistors grown by nitrogen plasma assisted molecular beam epitaxy

In this work, we demonstrate state of the art performance of GaN HFETs grown on SiC by rf Nitrogen plasma assisted molecular beam epitaxy (MBE) at 10 and 20 GHz and good power scalability of these devices at 10 GHz. A single stage power amplifier built by power combining four of our 1 mm devices exhibits continuous wave output power of 22.9 W with associated power added efficiency (PAE) of 37% at 9 GHz. This is to the best of our knowledge the highest CW power and the best combination of power and PAE demonstrated to date for a GaN based microwave integrated circuit at this frequency.

Microwave noise performance of AlGaN-GaN HEMTs with small DC power dissipation

We report low microwave noise performance of discrete AlGaN-GaN HEMTs at DC power dissipation comparable to that of GaAs-based low-noise FETs. At 1-V source-drain (SD) bias and DC power dissipation of 97 mW/mm, minimum noise figures (NF/sub min/) of 0.75 dB at 10 GHz and 1.5 dB at 20 GHz were achieved, respectively. A device breakdown voltage of 40 V was observed. Both the low microwave noise performance at small DC power level and high breakdown voltage was obtained with a shorter SD spacing of 1.5 /spl mu/m in 0.15-/spl mu/m gate length GaN HEMTs. By comparison, NF/sub min/ with 2 /spl mu/m SD spacing was 0.2 dB greater at 10 GHz.

164-GHz MMIC HEMT doubler

In this paper, a MMIC frequency doubler based on an InP HEMT and grounded CPW (GCPW) technology is reported. The doubler demonstrated a conversion loss of only 2 dB and output power of 5 dBm at 164 GHz. The 3 dB output power bandwidth is 14 GHz, or 8.5%. This is the best reported result for a MMIC HEMT doubler above 100 GHz.

A high-gain monolithic D-band InP HEMT amplifier

A three-stage monolithic amplifier has been developed which exhibits a measured small-signal gain of 30 dB at 140 GHz. The circuit employs 0.1-/spl mu/m AlInAs-GaInAs-InP HEMT devices with 150 /spl mu/m gate peripheries, and occupies a total area of 2 mm/sup 2/. Measured gain exceeds 10 dB from 129-157 GHz and 5 dB up to 184 GHz. This is the highest gain per stage ever reported in a transistor amplifier operating at these frequencies.

W-band InP HEMT MMICs using finite-ground coplanar waveguide (FGCPW) design

In this paper, we report on the development of W-band monolithic microwave integrated circuit (MMIC) power amplifiers using 0.1-/spl mu/m AlInAs/GaInAs/InP high electron mobility transistor (HEMT) technology and finite-ground coplanar waveguide (FGCPW) designs. In the device modeling, the Angelov nonlinear HEMT model was employed to predict the large signal performance of the device, and the results were validated by using state-of-the-art vector load-pull measurements. A two-stage single-ended W-band FGCPW MMIC using a 150-/spl mu/m-wide HEMT as the driver and a 250-/spl mu/m-wide HEMT for the output stage was designed, fabricated, and tested. The MMIC amplifier demonstrates a maximum output power of 18.6 dBm with 18.2% power-added efficiency and 10.6 dB associated gain at 94 GHz. This result is the best output power to date reported from an InP-based MMIC using FGCPW design at this frequency.

80 GHz MMIC HEMT VCO

In this letter a monolithic voltage-controlled oscillator (VCO) operating in the 77.5-83.5 GHz range is presented. InP HEMTs are used for both the active device and varactor. The VCO demonstrated a tuning range of 6 GHz and an output power better than 12.5 dBm in the entire tuning range.

GaN HFET technology for RF applications

GaN HFET has emerged as a very promising device technology for next-generation microwave applications. The last several years have witnessed a tremendous progress in the development of this technology, from material growth to circuit demonstration. Devices and circuits with excellent output power, power density, efficiency, and noise figure have been achieved. This talk reviews the current status of GaN HFET technology.

Next generation HEMTs

The High Electron Mobility Transistor (HEMT) device structure has played a significant role in analog and digital integrated circuit technology since the early 1980s. The development of the HEMT followed a typical path from fundamental studies of materials to device design and modeling. As the HEMT developed, the details of the device layer structure also evolved. In fact, the original GaAs/AlGaAs HEMT is now obsolete, while other HEMT technologies, such as the InGaAs/AlGaAs pseudomorphic HEMT (PHEMT) and the InP based InGaAs/InAlAs HEMT, have fully matured. Most recent work related to PHEMT and InP HEMT technologies has focused on device integration, circuit and system development, device manufacturability, and reliability issues. As such, device performance progress, relatively speaking, has slowed. At HRL we are investigating new combinations of materials which may lead to significant improvements in existing HEMT and PHEMT devices. The focus of our research is mixed antimonide phosphide (SbP) and mixed antimonide arsenide (SbAs) compounds. In particular, AlGaPSb, which can be grown lattice matched to both InP and GaAs, and InAlAsSb on InP. These compounds offer larger energy bandgaps and larger conduction band offsets than the more commonly used compounds (InAlAs for InP HEMTs and AlGaAs for PHEMTs). Hence, they should lead to devices that have higher sheet carrier concentration, higher breakdown voltage, higher turn-on voltage, higher gain, higher current, higher output power, improved power added efficiency, and lower noise figure.

W-band InP-based HEMT MMIC power amplifiers using finite-ground CPW design

In this paper we report on the development of W-band MMIC power amplifiers using 0.1 /spl mu/m AlInAs-GaInAs-InP HEMT technology and finite-ground coplanar waveguide (FGCPW) designs. Two single-stage single-ended W-band MMICs using 150 /spl mu/m and 250 /spl mu/m wide HEMTs were designed, fabricated and tested. The results show that the small signal performance of the MMIC using the 150 /spl mu/m wide HEMT has a linear gain of more than 12 dB at 94 GHz. The corresponding amplifier exhibits an output power of 13.8 dBm with a power-added efficiency of 23%. The MMIC using the 250 /spl mu/m wide HEMT demonstrates 9 dB linear gain and the amplifier has a maximum output power of 16.7 dBm with 17.5% power added efficiency at 94 GHz. These power amplifiers are the first ever reported using a CPW configuration at this frequency.

K-band GaN power HFET's with 6.6 W/mm CW saturated output power density and 35% power added efficiency at 20 GHz

AlGaN/GaN heterostructure field effect transistors (HFETs) grown on SiC substrates are currently the most powerful three-terminal microwave solid state devices. While the power performance of these devices is well documented at X-band frequencies, there is growing interest in these devices at higher frequencies. In this study we characterize the power performance of GaN HFETs at 20 GHz. Our results clearly show that GaN HFETs have strong potential for power applications at K-band frequencies and beyond.