Power PHEMT Research Articles

Bias-dependent Access Resistances Extraction in 0.15 µm GaAs pHEMTs

Devices’ performance analysis and successful circuit design strongly depend on accurate large signal models. This, in turn, requires accurate small signal models. However, the reliable parasitic parameter extraction of GaAs pHEMT greatly influences the accuracy of small signal models, which also greatly influences the extraction of intrinsic elements. The access parasitic source and drain resistances, Rs and Rd, are associated with gate bias due to the two-dimensional charge control. In this work, we directly extract Rs and Rd from S-parameter measurements of the device under test (DUT) under strong inversion operating biases. The proposed method has been validated by simulation and on-wafer measurements. It shows better accuracy than existing arts in a frequency range of 0.5–40 GHz (0.5 GHz step). Furthermore, a 10-15 GHz GaAs pHEMT power amplifier (PA) is employed to further validate the developed method. The test results also validate the developed method.

A New Method to Extract Gate Bias-Dependent Parasitic Resistances in GaAs pHEMTs

Accurate large signal GaAs pHEMT models are essential for devices’ performance analysis and microwave circuit design. This, in turn, mandates precise small signal models. However, the accuracy of small signal models strongly depends on reliable parasitic parameter extraction of GaAs pHEMT, which also greatly influences the extraction of intrinsic elements. Specifically, the parasitic source and drain resistances, R s and R d , are gate bias-dependent, due to the two-dimensional charge variations. In this paper, we propose a new method to extract R s and R d directly from S-parameter measurements of the device under test (DUT), which save excessive measurements and complicated parameter extraction. We have validated the proposed method in both simulation and on-wafer measurement, which achieves better accuracy than the existing state-of-the-art in a frequency range of 0.5–40 GHz. Furthermore, we develop a GaAs pHEMT power amplifier (PA) to further validate the developed model. The measurement results of the PA at 9–15 GHz agree with the simulation results using the proposed model.

Wideband 5 W Ka-Band GaAs Power Amplifier

This letter presents a Ka-Band 0.1-μm GaAs pHEMT Power Amplifier with broad bandwidth. The isolating backvia wall (IBVW) has been proposed to improve the stability and performance. Over the frequency band of 31-40 GHz, implemented PA delivers 5 W saturated output power, 28% maximum power added efficiency (PAE) and 20 dB maximum small-signal gain. The chip size of the PA is 11.9 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . To the best of authors knowledge, the presented PA demonstrates widest bandwidth in Ka-band GaAs PAs while maintaining compact size.

A Ka-Band 150 nm GaAs pHEMT Power Amplifier Monolithic Microwave Integrated Circuit with Novelly Designed Output Power Combining Networks

A Ka-Band 150 nm GaAs pHEMT Power Amplifier Monolithic Microwave Integrated Circuit with Novelly Designed Output Power Combining Networks

A systematic design of 1.5-9 GHz high power-high efficiency two-stage GaAs PHEMT power amplifier

In this article, a systematic design approach for a Class-A operated wideband power amplifier is presented. The power amplifier structure comprises of two transistors in the cascaded single stage traveling wave amplifier topology. A power amplifier was designed by using the systematic approach and fabricated with 0.25 µm GaAs PHEMT MMIC process. The amplifier has an area of 3.4 × 1.4 mm2. Measurement results show that almost flat gain performance is obtained around 15 dB over 1.5-9 GHz operating bandwidth. In most of the band, with the help of a wideband load-pull matching technique, the amplifier delivers Po,sat and Po,1dB of around 30 dBm and 28 dBm where the corresponding power added efficiencies are >50% and >36%, respectively. It is shown that the proposed design approach has the advantage of simple and systematic design flow and it helps to realize step-by-step design for the designers. © 2014 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:615-622, 2014.

A complete and accurate surface-potential based large-signal model for compound semiconductor HEMTs

A complete and accurate surface potential based large-signal model for compound semiconductor HEMTs is presented. A surface potential equation resembling the one used in conventional MOSFET models is achieved. The analytic solutions from the traditional surface potential theory that developed in MOSFET models are inherited. For core model derivation, a novel method is used to realize a direct application of the standard surface potential model of MOSFETs for HEMT modeling, without breaking the mathematic structure. The high-order derivatives of I—V/C—V remain continuous, making the model suitable for RF large-signal applications. Furthermore, the self-heating effects and the transconductance dispersion are also modelled. The model has been verified through comparison with measured DC IV, Gummel symmetry test, CV, minimum noise figure, small-signal S - parameters up to 66 GHz and single-tone input power sweep at 29 GHz for a 4 × 75 μm × 0.1 μm InGaAs/GaAs power pHEMT, fabricated at a commercial foundry.

Extraction of a Model for a Microwave Power pHEMT

This article presents the development of a large-signal transistor model for a power microwave pseudomorphic high-electron mobility transistor (pHEMT). This model won the first prize in the Microwave Transistor Modeling student competition held during the 2013 IEEE Microwave Theory and Techniques Society (MTT-S) International Microwave Symposium (IMS2013) in Seattle, Washington.

GaAs P-HEMT MMIC processes behavior under multiple heavy ion radiation stress conditions combined with DC and RF biasing

Two European GaAs power P-HEMT MMIC processes using representative test structures have been characterized in situ when irradiated by high energy heavy ion radiation beam (420MeV Xenon source, LET=46.6MeVcm2/mg), and under various worst case bias including DC and high drive RF conditions applied. The test methodology conducted has been carefully defined in order to help to early discriminate failure mechanisms induced by biasing stresses from those possibly induced by heavy ion irradiation environment. It is demonstrated that the two P-HEMT processes tested under worst case application biasing conditions (both cumulated DC and RF) are immune to heavy ion radiation stress representative of harsh space environments.

ANN modeling for design of a matched low noise pHEMT amplifier for mobile application

For high quality performance, future efficient wireless communication systems require a Broadband Amplifier in the frequency range under consideration. When such an amplifier is plugged into the measuring path it would enable the system to perceive even the weakest of signals. To achieve this, a new Scattering-parameter model that is valid for a wide frequency range has been developed for microwave analysis of a pseudomorphic high electron mobility transistors (pHEMT). The developed neural network model is used for designing a pHEMT power amplifier. The calculated S-parameters, gain and minimum noise figure from the artificial neural networks (ANN) model are the parameters used to design the low noise pHEMT power amplifier. The various gains so obtained from the S-parameters have been plotted with the frequency and it was found to yield a close fit to the simulated model. Neural network training has been done using Levenberg-Marqaurdt back propagation algorithm implemented in ANN toolbox of MATLAB software. All the results have been compared with the experimental data that showed a close agreement and validated our model. The calculated S-parameters, gain and minimum noise figure from the ANN model are the parameters used to design a stabilized and matched LNA.

Reliability analysis of pHEMT power amplifier with an on-chip linearizer

The hot carrier reliability and self-heating of the Al0.3Ga0.7As/In0.25Ga0.75As pHEMT has been examined using mixed-mode simulation. A two-stage power amplifier using 0.15μm InGaAs pHEMT technology with an on-chip linearizer has been designed and fabricated for the evaluation of electrical stress on RF circuit performances. The power amplifier was subjected to high RF input power while doubling the supply voltage for accelerated aging. The experimental data of the amplifier’s output power, power-added efficiency, and linearity show little changes after 10h of continuous RF stress.

Novel MMIC Power Amplifier Linearization Utilizing Input Reflected Nonlinearity

This paper introduces a novel method to generate an auxiliary third-order intermodulation (IM3) signal, which can be used in the linearization of power amplifiers (PAs) by canceling the output IM3 power. This auxiliary signal is simply achieved by exploiting the input reflected power of the main device, rather than obtained by conventional methods as driving a highly nonlinear device or subtracting the fundamental power from the output signal. It is demonstrated that substantial IM3 power can be reflected to the source with little reflected fundamental power under some input matching conditions of the device, and this feature can be utilized in the design of monolithic microwave integrated circuits (MMICs) targeting excellent linearity. A 25-GHz pHEMT power amplifier is designed and fabricated to exemplify the proposed technique. With the linearization, the OIP3 of the proposed PA increases by 14 dB from 25 to 39 dBm, and the output power enhances significantly, from 5 to 14 dBm with -40-dBc IM3 distortion and from 9 to 14 dBm with -40-dBc adjacent channel power ratio.

A 17–35 GHz Broadband, High Efficiency PHEMT Power Amplifier Using Synthesized Transformer Matching Technique

This paper presents a 17 GHz to 35 GHz broadband power amplifier (PA) using 0.15-μm GaAs pHEMT technology. The synthesized transformer using microstrip line matching technique is proposed in this PA design to enhance the broadband frequency response and minimize the chip size. The design procedures are also presented. A high efficiency broadband PA in commercial 0.15 μm GaAs pHEMT process with the best P <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1dB</sub> of 22 dBm, P <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">sat</sub> of 23.5 dBm, and PAE of 40% are demonstrated to verify the design concepts. This PA has the highest PAE, smallest chip size, and wide fractional bandwidth among the broadband GaAs HEMT PAs from K to Ka band.

An X-band ultra-low phase noise differential Colpitts voltage-controlled oscillator using 0.15 μm pseudomorphic high electron mobility transistor technology

A low phase noise and a high output power X-band differential Colpitts pseudomorphic high electron mobility transistor (pHEMT) voltage-controlled oscillator (VCO) is proposed in this study. In general, pHEMT achieves a lower noise up-conversion factor than heterojunction bipolar transistor because of the inherent linear behaviour at optimal gate bias voltage. Therefore, a high linearity 0.15 μm gate length power pHEMT with Colpitts architecture was beneficial for obtaining a low phase noise oscillator together with a high output power characteristic. It achieves an excellent figure of merit of −181.6 dBc/Hz and a power output of 0.67 dBm at 8.6 GHz. In this design, depletion-mode pHEMT was adopted in the VCO core, and a balanced structure was chosen for Colpitts topology to suppress undesired common-mode noise. The VCO was operated from 8.5 GHz to 9.35 GHz with 9.4% tuning range; the measured phase noises at 1 MHz offset were −105.6 dBc/Hz at 9 GHz and −120.46 dBc/Hz at 8.6 GHz, respectively. The current consumption of the VCO core was only 17.6 mA.

High Moisture Resistant and Reliable Gate Structure Design in High Power pHEMTs for Millimeter-Wave Applications

This paper reports the new gate and recess structure design of millimeter-wave, high power pHEMTs, which highly improves humidity resistance and reliability. By using tantalum nitride as the refractory gate metal and a silicon nitride layer prepared by a catalytic chemical vapor deposition technique for passivation of this transistor, strong moisture resistance was obtained without degradation of the device characteristics. Moreover, we have designed a stepped recess structure to increase the on-state breakdown voltage without degradation of the power density of the millimeter-wave pHEMT, according to the analysis based on the new nonlinear drain resistance model. Consequently, the developed pHEMT has shown strong humidity resistance with no degradation of the DC characteristics even after 1000 hours storage at 400K and 85% humidity, and the high on-state breakdown voltage of over 30V while keeping the high power density of 0.65W/mm in the Ka band. In addition, the proposed nonlinear drain resistance model effectively explains this power performance.

A fully matched 9 W compact PHEMT MMIC high power amplifier for X‐band phase array radar applications

AbstractThis paper presents a compact X‐band, 9 W AlGaAs/InGaAs/GaAs PHEMT MMIC high power amplifier. This amplifier is designed to fully match a 50 Ω input and output impedance. Based on 0.35 μm gate‐length power PHEMT technology, a two‐stage power amplifier is fabricated on a 3‐mil thick wafer. While operating under 9 V DC bias condition, the characteristics of 17 dB small‐signal gain, an average of 9 W continuous‐wave output power, and 34% power added efficiency from 9.0 to 10.5 GHz can be achieved. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 257–261, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22102

A low power and low noise p-HEMT ku band VCO

In this letter, we report a differential 12-GHz voltage-controlled oscillator (VCO) implemented using a commercial GaAs pseudomorphic high electron mobility transistor (p-HEMT) process. The VCO can operate with 3mW of dc power. The single-side-band phase noise at 1-MHz offset from the carrier is -116dBc and is achieved with 15mW of dc power consumption. This VCO has a figure of merit of -190.5dBc which is the best that has been reported for a p-HEMT VCO in the authors' knowledge

Off‐state and on‐state breakdown of GaAs MESFET, PHEMT and Power PHEMT

We present a comparison of the breakdown loci of a MESFET, PHEMT and Power PHEMT. It is based on the study of the correlation between breakdown loci and device output characteristics. This study aims at performing a technology choice for amplifier design operating in non linear conditions with operating level close to the maximum operating conditions of the transistor. We found that the MESFET is the best candidate for circuits operating in overdrive conditions as it presents abrupt on-state breakdown voltage loci and the highest breakdown voltage. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

A Ku band four-stage PHEMT 1W MMIC power amplifier

A successful development of a very high performance and reliable power PHEMT MMIC technology is reported. In this paper, a Ku-Band 1W AlGaAs/InGaAs/GaAs PHEMT MMIC power amplifier for VSAT ODU application is demonstrated. This four-stage amplifier is designed to fully match for a 50Ω input and output impedance. With 7V and 700mA DC bias condition, the amplifier has achieved 30dB small-signal gain, 30.8dBm 1-dB gain compression power with 24.5% power-added efficiency (PAE) and 31.3dBm saturation power with 27.5% PAE from 14 to 17GHz.

A new nonlinear capacitance model of millimeter wave power PHEMT for accurate AM/AM-AM/PM simulations

A new one-dimensional (1-D) nonlinear gate-source Cgs and gate-drain Cgd capacitance model designed for power-PHEMT transistors is presented. The capacitance values are extracted from measured [S] parameters, along a load-line corresponding to a power performance of an optimum amplifier design. The reliable resulting model predicts adequate power performances with small or large signals in reduced CPU time. This new model is validated by comparisons between load-pull power measurements at 25.5 GHz and harmonic balance simulations. It reveals good accuracy for AM/AM and AM/PM predictions.

Channel temperature measurement of PHEMT by means of optical probes

A novel technique for precise temperature measurement of high power PHEMTs is presented. The method, based on the measurement of photogenerated current, is used to extract the temperature of the PHEMT channel. Evaluation of thermal resistance is presented.