Michael Wojtowicz

0.10 /spl mu/m graded InGaAs channel InP HEMT with 305 GHz f/sub T/ and 340 GHz f/sub max/

We report here 305 GHz f/sub T/, 340 GHz f/sub max/, and 1550 mS/mm extrinsic g/sub m/ from a 0.10 /spl mu/m In/sub x/Ga/sub 1-x/As/In/sub 0.62/Al/sub 0.48/As/InP HEMT with x graded from 0.60 to 0.80. This device has the highest f/sub T/ yet reported for a 0.10 /spl mu/m gate length and the highest combination of f/sub T/ and f/sub max/ reported for any three-terminal device. This performance is achieved by using a graded-channel design which simultaneously increases the effective indium composition of the channel while optimizing channel thickness.<<ETX>>

Two‐dimensional electron gas effects in the electromodulation spectra of a pseudomorphic Ga0.78Al0.22As/In0.21Ga0.79As/GaAs modulation‐doped quantum well structure

We have studied the electroreflectance and photoreflectance spectra from a pseudomorphic Ga0.78Al0.22As/In0.21Ga0.79As/GaAs modulation‐doped quantum well (MDQW) structure in the temperature range 79<T<304 K. The features from the InGaAs MDQW can be accounted for on the basis of a two‐dimensional density of states and a Fermi level filling factor. A detailed line shape fit makes it possible to evaluate the Fermi energy, and hence the two‐dimensional electron gas concentration (Ns), as well as other important parameters of the structure. Our value for Ns is in good agreement with a Hall measurement.

Wideband Dual-Gate GaN HEMT Low Noise Amplifier for Front-End Receiver Electronics

A highly survivable wideband low noise amplifier (LNA) for front-end receiver electronics is presented utilizing 0.2 mum AlGaN/GaN HEMT process on SiC substrate. This novel amplifier utilizes dual-gate devices with current feedback and drain bias network to attain wideband performance in terms of lower noise and higher gain. Nominal operation at 125 mA/mm at a drain voltage of 10 volts provided 12.5 to 18 dB gain and 1.3 to 2.5 dB noise figure. Due to high breakdown voltage, the amplifier is capable of better than 25 dBm of output power and can withstand an input power level approaching 38 dBm. This paper will also document performance comparison with a similar circuit using 0.15 mum pseudomorphic InGaAs/AlGaAs/GaAs HEMT low noise amplifier to demonstrate the outstanding survivability of AlGaN/GaN low noise amplifiers

A 1–25 GHz GaN HEMT MMIC Low-Noise Amplifier

This letter presents an ultra-wideband low noise amplifier (LNA) using gallium-nitride (GaN) high-electron mobility transistors (HEMT) technology. A -3 dB bandwidth of 1-25 GHz with 13 dB peak power gain is achieved using a modified resistive-feedback topology. To obtain such a wide bandwidth, several bandwidth enhancement techniques are utilized. An inductor connected to the source of the input transistor ensures good input matching (|S11| <; -9 dB) across the entire bandwidth. The shunt feedback loop and the inductive source degeneration minimize all the required inductor values. This GaN HEMT LNA is believed to have the widest bandwidth among all GaN HEMT monolithic microwave integrated circuit (MMIC) LNAs reported to date. With 3.3 dB minimum noise figure (F), 33.5 dBm maximum output-referred third-order intercept point (OIP3), 20 dBm maximum output-referred 1 dB compression point (Output P1 dB), this MMIC amplifier is comparable in performance to distributed amplifiers (DAs) but with significantly lower power consumption and smaller area.

Design and Analysis of Ultra Wideband GaN Dual-Gate HEMT Low-Noise Amplifiers

In this paper, we present three ultra wide bandwidth low-noise amplifiers (LNAs) using dual-gate AlGaN/GaN HEMT devices. The single-stage, resistive feedback amplifiers target two different frequency bands: two LNAs operate in 0.3-4 GHz and one LNA is in 1.2-18 GHz. All three LNAs are capable of better than 13:1 bandwidth. The first low frequency amplifier uses a microstrip design and achieves 17.7 dB flat gain between 300 MHz-3 GHz, and 1.2 dB minimum noise figure around 1.3 GHz. The second 0.3-4 GHz LNA uses coplanar waveguide transmission lines and demonstrates 18 dB flat gain and 1.5 dB noise figure between 2 and 5 GHz. The high frequency microstrip-type LNA shows an average of 13 dB gain and between 2-3 dB noise figure across the band. The robust LNAs can be operated under various bias voltages while similar gain and noise figure performance are maintained.

A Q-band low phase noise monolithic AlGaN/GaN HEMT VCO

A Q-band 40-GHz GaN monolithic microwave integrated circuit voltage controlled oscillator (VCO) based on AlGaN/GaN high electron mobility transistor technology has been demonstrated. The GaN VCO delivered an output power of +25dBm with phase noise of -92dBc/Hz at 100-KHz offset, and -120dBc/Hz at 1-MHz offset. To the best of our knowledge, this represents the state-of-the-art for GaN VCOs in terms of frequency, output power, and phase noise performance. This work demonstrates the potential for the use of GaN technology for high frequency, high power, and low phase noise frequency sources for military and commercial applications

0.1 /spl mu/m InGaAs/InAlAs/InP HEMT MMICs - a flight qualified technology

0.1 /spl mu/m InGaAs/InAlAs/InP HEMT MMIC technology on 3- inch InP substrates has been qualified in the categories of three-temperature lifetest, gamma radiation, RF survivability, electrostatic discharge, via-hole baking, and H/sub 2/ poisoning. The three-temperature lifetest (T/sub 1/ = 215/spl deg/C, T/sub 2/ = 230/spl deg/C and T/sub 3/ = 250/spl deg/C) of 0.1 /spl mu/m InGaAs/InAlAs/InP HEMT MMICs in a N/sub 2/ ambient demonstrates an activation energy (Ea) as high as 1.9 eV, achieving a projected median-time-to-failure (MTF) /spl ap/ 1/spl times/10/sup 8/ hours at a 125/spl deg/C junction temperature. Gamma radiation up to 5 mega RAD dose does not induce any degradation of DC/RF characteristics. Electrostatic discharge (ESD) shows destructive voltage up to 100 Volts. Furthermore, 0.1 /spl mu/m InP HEMTs exhibit less sensitivity to H/sub 2/ exposure than 0.1 /spl mu/m GaAs pseudomorphic HEMTs. The qualification results demonstrate the readiness of 0.1 /spl mu/m InGaAs/InAlAs/InP MMICs technology for flight applications.

Surface photovoltage spectroscopy of a GaAs/AlGaAs heterojunction bipolar transistor

The electronic properties of a GaAs/AlGaAs heterojunction bipolar transistor (HBT) structure have been studied by surface photovoltage spectroscopy. The p-base band-gap narrowing has been determined and confirmed by numerical simulation. Based on the shape of the surface photovoltage spectrum, it is possible to monitor the doping level and evaluate the minority-carrier mobility. This work demonstrates the power of the technique as a precision tool for HBT quality control.

Commercial heterojunction bipolar transistor production by molecular beam epitaxy

We have developed the first commercial heterojunction bipolar transistor (HBT) production line based on GaAs–AlGaAs–InGaAs HBT material grown by molecular beam epitaxy. We have demonstrated sustained high‐yield production of HBT integrated circuits for commercial applications using molecular beam epitaxy growth and processing techniques originally developed for high‐reliability applications. TRW HBT parts such as cellular power amplifiers, digital radio chip sets, Darlington gain blocks, and analog‐to‐digital convertors are now inserted in high volume commercial products such as cellular phones, local area networks, and digital oscilloscopes. HBT monolithic microwave integrated circuits allow these products to achieve functions and performance never before available for consumer applications.

A V-Band Monolithic AlGaN/GaN VCO

A V-band push-push GaN monolithic microwave integrated circuit voltage controlled oscillator (VCO) has been realized based on a 0.2 mum T-gate AlGaN/GaN high electron mobility transistor technology with an fT ~ 65 GHz. The GaN VCO delivered an output power of +11 dBm at 53 GHz with an estimated phase noise of -97 dBc/Hz at 1 MHz offset based on on-wafer measurement. To the best of our knowledge, this is the highest frequency VCO ever reported for GaN technology with a high output power at V-band, without using any buffer amplifier. This work demonstrates the potential of applying GaN technology to millimeter wave band, high power, and low phase noise frequency sources applications.