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  • 1.
    Azam, Sher
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Microwave Power Devices and Amplifiers for Radars and Communication Systems2009Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    SiC MESFETs and GaN HEMTs posses an enormous potential in power amplifiers at microwave frequencies due to their wide bandgap features of high electric field strength, high electron saturation velocity and high operating temperature. The high power density combined with the comparably high impedance attainable by these devices also offers new possibilities for wideband power microwave systems. Similarly Si-LDMOS being low cost and lonely silicon based RF power transistor has great contributions especially in the communication sector.

    The focus of this thesis work is both device study and their application in different classes of power amplifiers. In the first part of our research work, we studied the performance of transistors in device simulation using physical transistor structure in Technology Computer Aided Design (TCAD). A comparison between the physical simulations and measured device characteristics has been carried out.  We optimized GaN HEMT, Si-LDMOS and enhanced version of our previously fabricated and tested SiC MESFET transistor for enhanced RF and DC characteristics. For large signal AC performance we further extended the computational load pull (CLP) simulation technique to study the switching response of the power transistors. The beauty of our techniques is that, we need no lumped or distributive matching networks to study active device behavior in almost all major classes of power amplifiers. Using these techniques, we studied class A, AB, pulse input class-C and class-F switching response of SiC MESFET. We obtained maximum PAE of 78.3 % with power density of 2.5 W/mm for class C and 84 % for class F power amplifier at 500 MHz. The Si-LDMOS has a vital role and is a strong competitor to wideband gap semiconductor technology in communication sector. We also studied Si-LDMOS (transistor structure provided by Infineon Technologies at Kista, Stockholm) for improved DC and RF performance. The interface charges between the oxide and RESURF region are used not only to improve DC drain current and RF power, gain & efficiency but also enhance its operating frequency up to 4 GHz.

    In the second part of our research work, six single stage (using single transistor) power amplifiers have been designed, fabricated and characterized in three phases for applications in communications, Phased Array Radars and EW systems. In the first phase, two class AB power amplifiers are designed and fabricated. The first PA (26 W) is designed and fabricated at 200-500 MHz using SiC MESFET. Typical results for this PA at 60 V drain bias at 500 MHz are, 24.9 dB of power gain, 44.15 dBm output power (26 W) and 66 % PAE. The second PA is designed at 30-100 MHz using SiC MESFET. At 60 V drain bias Pmax is 46.7 dBm (~47 W) with a power gain of 21 dB.

    In the second phase, for performance comparison, three broadband class AB power amplifiers are designed and fabricated at 0.7-1.8 GHz using SiC MESFET and two different GaN HEMT technologies (GaN HEMT on SiC and GaN HEMT on Silicon substrate). The measured maximum output power for the SiC MESFET amplifier at a drain bias of Vd= 66 V at 700 MHz the Pmax was 42.2 dBm (~16.6 W) with a PAE of 34.4 %. The results for GaN HEMT on SiC amplifier are; maximum output power at Vd = 48 V is 40 dBm (~10 W), with a PAE of 34 % and a power gain above 10 dB. The maximum output power for GaN HEMT on Si amplifier is 42.5 dBm (~18 W) with a maximum PAE of 39 % and a gain of 19.5 dB.

    In the third phase, a high power single stage class E power amplifier is implemented with lumped elements at 0.89-1.02 GHz using Silicon GaN HEMT as an active device. The maximum drain efficiency (DE) and PAE of 67 and 65 % respectively is obtained with a maximum output power of 42.2 dBm (~ 17 W) and a maximum power gain of 15 dB.

    List of papers
    1. Pulse Input Class-C Power Amplifier Response of SiC MESFET using Physical Transistor Structure in TCAD
    Open this publication in new window or tab >>Pulse Input Class-C Power Amplifier Response of SiC MESFET using Physical Transistor Structure in TCAD
    2008 (English)In: Solid-State Electronics, ISSN 0038-1101, E-ISSN 1879-2405, Vol. 52, no 5, p. 740-744Article in journal (Refereed) Published
    Abstract [en]

    The switching behavior of a previously fabricated and tested SiC transistor is studied in Class-C amplifier in TCAD simulation. The transistor is simulated for pulse input signals in Class-C power amplifier. The simulated gain (dB), power density (W/mm) and power added efficiency (PAE%) at 500 MHz, 1, 2 and 3 GHz was studied using computational TCAD load pull simulation technique. A Maximum PAE of 77.8% at 500 MHz with 45.4 dB power gain and power density of 2.43 W/mm is achieved. This technique allows the prediction of switching response of the device for switching amplifier Classes (Class-C–F) before undertaking an expensive and time consuming device fabrication. The beauty of this technique is that, we need no matching and other lumped element networks for studying the large signal behavior of RF and microwave transistors.

    Keywords
    Pulse, Class-C, Power amplifier, New technique, Silicon carbide, MESFET
    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:liu:diva-13285 (URN)10.1016/j.sse.2007.09.022 (DOI)
    Available from: 2008-05-13 Created: 2008-05-13 Last updated: 2017-12-13Bibliographically approved
    2. High Power, High Efficiency SiC Power Amplifier for Phased ArrayRadar and VHF Applications
    Open this publication in new window or tab >>High Power, High Efficiency SiC Power Amplifier for Phased ArrayRadar and VHF Applications
    (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    Wide band gap semiconductor (SiC & GaN) based power amplifiers offer severalsystem critical advantages such as less current leakage, better stability at high temperatureand easier impedance matching. This paper describes the design and fabrication of a singlestageclass-AB power amplifier for 30 to 100 MHz using SiC Schottky gate MetalSemiconductor Field Effect Transistor (MESFET). The maximum output power achieved is46.2 dBm (~42 W) at 50 V DC supply voltage at the drain. The maximum power gain is 21dB and a maximum PAE of 62 %. The amplifier performance was also checked at a higherdrain bias of 60 V at 50 MHz. At this bias voltage the maximum output power was 46.7dBm (~47 W) with a power gain of 21 dB and a maximum PAE of 42.7 %. An averageOIP3 of 54 dBm have been achieved for this amplifier.

    Keywords
    Power Amplifier, Phased Array Radar, VHF, Silicon Carbide and MESFET.
    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:liu:diva-20862 (URN)
    Available from: 2009-09-24 Created: 2009-09-24 Last updated: 2018-10-08Bibliographically approved
    3. Single-stage, High Efficiency, 26-Watt power Amplifier using SiC LE-MESFET
    Open this publication in new window or tab >>Single-stage, High Efficiency, 26-Watt power Amplifier using SiC LE-MESFET
    2006 (English)In: Microwave Conference, 2006. APMC 2006. Asia-Pacific December 12-15, 2006, p. 441-444Conference paper, Published paper (Refereed)
    Abstract [en]

    This paper describes a single-stage 26 W negative feedback power amplifier, covering the frequency range 200-500 MHz using a 6 mm gate width SiC lateral epitaxy MESFET. Typical results at 50 V drain bias for the whole band are, around 22 dB power gain, around 43 dBm output power, minimum power added efficiency at P1 dB is 47% at 200 MHz and maximum 60% at 500 MHz and the IMD3 level at 10 dB back-off from P1 dB is below -45 dBc. The results at 60 V drain bias at 500 MHz are, 24.9 dB power gain, 44.15 dBm output power (26 W) and 66% PAE.

    Keywords
    Schottky gate field effect transistors, feedback, microwave power amplifiers, silicon compounds, SiC, frequency 200 MHz to 500 MHz, lateral epitaxy MESFET, negative feedback, power 26 W, power amplifier, size 6 mm, voltage 50 V
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-13283 (URN)10.1109/APMC.2006.4429458 (DOI)
    Available from: 2008-05-13 Created: 2008-05-13 Last updated: 2009-09-24Bibliographically approved
    4. Broadband Power Amplifier performance of SiC MESFET and CostEffective SiGaN HEMT
    Open this publication in new window or tab >>Broadband Power Amplifier performance of SiC MESFET and CostEffective SiGaN HEMT
    (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    This paper describes the broadband power amplifier performance of two differentwide band gap technology transistors at 0.7 to 1.8 GHz using cost effective NitronexGaN HEMT on Silicon (Si) and Cree Silicon Carbide MESFET. The measured resultsfor GaN amplifier are; maximum output power at Vd = 28 V is 42.5 dBm (~18 W), amaximum PAE of 39 % and a maximum gain of 19.5 dB is obtained. The measuredmaximum output power for the SiC amplifier at Vd = 48 V was 41.3 dBm (~13.7 W),with a PAE of 32 % and a power gain above 10 dB. At a drain bias of Vd = 66 V at700 MHz for SiC MESFET amplifier the Pmax was 42.2 dBm (~16.6 W) with a PAE of34.4 %.

    Keywords
    Broadband, Power Amplifier, GaN HEMT, Silicon Carbide (SiC), MESFET
    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:liu:diva-20863 (URN)
    Available from: 2009-09-24 Created: 2009-09-24 Last updated: 2010-01-14Bibliographically approved
    5. Designing, Fabrication and Characterization of Power Amplifiers Based on 10-Watt SiC MESFET & GaN HEMT at Microwave Frequencies
    Open this publication in new window or tab >>Designing, Fabrication and Characterization of Power Amplifiers Based on 10-Watt SiC MESFET & GaN HEMT at Microwave Frequencies
    2008 (English)In: IEEE European Microwave Week, October 10-15, Amsterdam, The Netherlands, 2008, p. 444-447Conference paper, Published paper (Refereed)
    Abstract [en]

    This paper describes the design, fabrication and measurement of two single-stage class-AB power amplifiers covering the frequency band from 0.7-1.8 GHz using a SiC MESFET and a GaN HEMT. The measured maximum output power for the SiC amplifier at Vd = 48 V was 41.3 dBm (~13.7 W), with a PAE of 32% and a power gain above 10 dB. At a drain bias of Vd= 66 V at 700 MHz the Pmax was 42.2 dBm (~16.6 W) with a PAE of 34.4%. The measured results for GaN amplifier are; maximum output power at Vd = 48 V is 40 dBm (~10 W), with a PAE of 34% and a power gain above 10 dB. The results for SiC amplifier are better than for GaN amplifier for the same 10-W transistor.

    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:liu:diva-13284 (URN)10.1109/EUMC.2008.4751484 (DOI)
    Available from: 2008-05-13 Created: 2008-05-13 Last updated: 2009-09-24Bibliographically approved
    6. High Power, Single Stage SiGaN HEMT Class EPower Amplifier at GHz Frequencies
    Open this publication in new window or tab >>High Power, Single Stage SiGaN HEMT Class EPower Amplifier at GHz Frequencies
    Show others...
    (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    A high power single stage class E power amplifier is implemented with lumped elements at 0.89-1.02GHz using Silicon GaN High Electron Mobility Transistor as an active device. The maximum drain efficiency (DE) and power added efficiency (PAE) of 67 and 65 % respectively is obtained with a maximum output power of 42.2 dBm (~ 17 W) and amaximum power gain of 15 dB. We obtained good results at all measured frequencies.

    Keywords
    Class E, PAE, Power Amplifiers, Gallium Nitride, HEMT
    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:liu:diva-20864 (URN)
    Available from: 2009-09-24 Created: 2009-09-24 Last updated: 2019-09-05Bibliographically approved
    7. A New Load Pull TCAD Simulation Technique for Class D, E & FSwitching Characteristics of Transistors
    Open this publication in new window or tab >>A New Load Pull TCAD Simulation Technique for Class D, E & FSwitching Characteristics of Transistors
    (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    We have further developed a computational load pull simulation technique inTCAD. It can be used to study the Class-D, E & F switching response of the transistors. Westudied our enhanced version of previously fabricated and tested SiC transistor. Thesimulated Gain (dB), Power density (W/mm), switching loss (W/mm) and power addedefficiency (PAE %) at 500 MHz were studied using this technique. A PAE of 84 % at500MHz with 26 dB Power gain and power density of 2.75 W/mm is achieved. Thistechnique allows the prediction of switching response of the device before undertaking anexpensive and time-consuming device fabrication. The beauty of this technique is that, weneed no matching and other lumped element networks to study the large signal switchingbehavior of RF and microwave transistors.

    Keywords
    Power Amplifier, Silicon Carbide, TCAD, Switching, Technique
    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:liu:diva-20865 (URN)
    Available from: 2009-09-24 Created: 2009-09-24 Last updated: 2010-01-14Bibliographically approved
    8. Influence of interface state charges on RF performance of LDMOS transistor
    Open this publication in new window or tab >>Influence of interface state charges on RF performance of LDMOS transistor
    Show others...
    2008 (English)In: Solid-State Electronics, ISSN 0038-1101, E-ISSN 1879-2405, Vol. 52, no 7, p. 1099-1105Article in journal (Refereed) Published
    Abstract [en]

    Si-LDMOS transistor is studied by TCAD simulation for improved RF performance. In LDMOS structure, a low-doped reduced surface field (RESURF) region is used to obtain high breakdown voltage, but it reduces the transistor RF performance due to high on-resistance. The interface charges between oxide and the RESURF region are studied and found to have a strong impact on the transistor performance both in DC and RF. The presence of excess interface state charges at the RESURF region results not only higher DC drain current but also improved RF performance in terms of power, gain and efficiency. The most important achievement is the enhancement of operating frequency and RF output power is obtained well above 1 W/mm up to 4 GHz.

    Place, publisher, year, edition, pages
    Elsevier, 2008
    Keywords
    Semiconductor devices; Interface state charges; Power electronics; Amplifiers; CAD simulations
    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:liu:diva-20866 (URN)10.1016/j.sse.2008.04.001 (DOI)
    Available from: 2009-09-24 Created: 2009-09-24 Last updated: 2017-12-13Bibliographically approved
    9. Comparison of Two GaN TransistorsTechnology in Broadband Power Amplifiers
    Open this publication in new window or tab >>Comparison of Two GaN TransistorsTechnology in Broadband Power Amplifiers
    (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    This paper compares the performance of two different GaN technology transistors(GaN HEMT on Silicon substrate (PA1) and GaN on SiC PA2) utilized in two broadbandpower amplifiers at 0.7-1.8 GHz. The study explores the broadband power amplifierpotential of both GaN HEMT technologies for Phased Array Radar (PAR) and electronicswarfare (EW) systems. The measured maximum output power for PA1 is 42.5 dBm(~18 W) with a maximum PAE of 39 % and a gain of 19.5 dB. While the measuredmaximum output power for PA2 is 40 dBm with PAE of 35 % and a power gain slightlyabove 10 dB. We obtained high power, gain, wider band width and unconditionalstability without feedback for amplifier based on GaN HEMT technology fabricated on Sisubstrate.

    Keywords
    Broadband, Power Amplifier, GaN, HEMT and Single-Stage
    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:liu:diva-20867 (URN)
    Available from: 2009-09-24 Created: 2009-09-24 Last updated: 2010-01-14Bibliographically approved
  • 2.
    Azam, Sher
    Linköping University, Department of Physics, Chemistry and Biology, Materials Science . Linköping University, The Institute of Technology.
    Wide Bandgap Semiconductor (SiC & GaN) Power Amplifiers in Different Classes2008Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    SiC MESFETs and GaN HEMTs have an enormous potential in high-power amplifiers at microwave frequencies due to their wide bandgap features of high electric breakdown field strength, high electron saturation velocity and high operating temperature. The high power density combined with the comparably high impedance attainable by these devices also offers new possibilities for wideband power microwave systems. In this thesis, Class C switching response of SiC MESFET in TCAD and two different generations of broadband power amplifiers have been designed, fabricated and characterized. Input and output matching networks and shunt feedback topology based on microstrip and lumped components have been designed, to increase the bandwidth and to improve the stability. The first amplifier is a single stage 26-watt using a SiC MESFET covering the frequency from 200-500 MHz is designed and fabricated. Typical results at 50 V drain bias for the whole band are, 22 dB power gain, 43 dBm output power, minimum power added efficiency at P 1dB is 47 % at 200 MHz and maximum 60 % at 500 MHz and the IMD3 level at 10 dB back-off from P 1dB is below ‑45 dBc. The results at 60 V drain bias at 500 MHz are, 24.9 dB power gain, 44.15 dBm output power (26 W) and 66 % PAE.

    In the second phase, two power amplifiers at 0.7-1.8 GHz without feed back for SiC MESFET and with feedback for GaN HEMT are designed and fabricated (both these transistors were of 10 W). The measured maximum output power for the SiC amplifier at Vd = 48 V was 41.3 dBm (~13.7 W), with a PAE of 32 % and a power gain above 10 dB. At a drain bias of Vd= 66 V at 700 MHz the Pmax was 42.2 dBm (~16.6 W) with a PAE of 34.4 %. The measured results for GaN amplifier are; maximum output power at Vd = 48 V is 40 dBm (~10 W), with a PAE of 34 % and a power gain above 10 dB. The SiC amplifier gives better results than for GaN amplifier for the same 10 W transistor.

    A comparison between the physical simulations and measured device characteristics has also been carried out. A novel and efficient way to extend the physical simulations to large signal high frequency domain was developed in our group, is further extended to study the class-C switching response of the devices. By the extended technique the switching losses, power density and PAE in the dynamics of the SiC MESFET transistor at four different frequencies of 500 MHz, 1, 2 and 3 GHz during large signal operation and the source of switching losses in the device structure was investigated. The results obtained at 500 MHz are, PAE of 78.3%, a power density of 2.5 W/mm with a switching loss of 0.69 W/mm. Typical results at 3 GHz are, PAE of 53.4 %, a power density of 1.7 W/mm with a switching loss of 1.52 W/mm.

    List of papers
    1. Single-stage, High Efficiency, 26-Watt power Amplifier using SiC LE-MESFET
    Open this publication in new window or tab >>Single-stage, High Efficiency, 26-Watt power Amplifier using SiC LE-MESFET
    2006 (English)In: Microwave Conference, 2006. APMC 2006. Asia-Pacific December 12-15, 2006, p. 441-444Conference paper, Published paper (Refereed)
    Abstract [en]

    This paper describes a single-stage 26 W negative feedback power amplifier, covering the frequency range 200-500 MHz using a 6 mm gate width SiC lateral epitaxy MESFET. Typical results at 50 V drain bias for the whole band are, around 22 dB power gain, around 43 dBm output power, minimum power added efficiency at P1 dB is 47% at 200 MHz and maximum 60% at 500 MHz and the IMD3 level at 10 dB back-off from P1 dB is below -45 dBc. The results at 60 V drain bias at 500 MHz are, 24.9 dB power gain, 44.15 dBm output power (26 W) and 66% PAE.

    Keywords
    Schottky gate field effect transistors, feedback, microwave power amplifiers, silicon compounds, SiC, frequency 200 MHz to 500 MHz, lateral epitaxy MESFET, negative feedback, power 26 W, power amplifier, size 6 mm, voltage 50 V
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-13283 (URN)10.1109/APMC.2006.4429458 (DOI)
    Available from: 2008-05-13 Created: 2008-05-13 Last updated: 2009-09-24Bibliographically approved
    2. Designing, Fabrication and Characterization of Power Amplifiers Based on 10-Watt SiC MESFET & GaN HEMT at Microwave Frequencies
    Open this publication in new window or tab >>Designing, Fabrication and Characterization of Power Amplifiers Based on 10-Watt SiC MESFET & GaN HEMT at Microwave Frequencies
    2008 (English)In: IEEE European Microwave Week, October 10-15, Amsterdam, The Netherlands, 2008, p. 444-447Conference paper, Published paper (Refereed)
    Abstract [en]

    This paper describes the design, fabrication and measurement of two single-stage class-AB power amplifiers covering the frequency band from 0.7-1.8 GHz using a SiC MESFET and a GaN HEMT. The measured maximum output power for the SiC amplifier at Vd = 48 V was 41.3 dBm (~13.7 W), with a PAE of 32% and a power gain above 10 dB. At a drain bias of Vd= 66 V at 700 MHz the Pmax was 42.2 dBm (~16.6 W) with a PAE of 34.4%. The measured results for GaN amplifier are; maximum output power at Vd = 48 V is 40 dBm (~10 W), with a PAE of 34% and a power gain above 10 dB. The results for SiC amplifier are better than for GaN amplifier for the same 10-W transistor.

    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:liu:diva-13284 (URN)10.1109/EUMC.2008.4751484 (DOI)
    Available from: 2008-05-13 Created: 2008-05-13 Last updated: 2009-09-24Bibliographically approved
    3. Pulse Input Class-C Power Amplifier Response of SiC MESFET using Physical Transistor Structure in TCAD
    Open this publication in new window or tab >>Pulse Input Class-C Power Amplifier Response of SiC MESFET using Physical Transistor Structure in TCAD
    2008 (English)In: Solid-State Electronics, ISSN 0038-1101, E-ISSN 1879-2405, Vol. 52, no 5, p. 740-744Article in journal (Refereed) Published
    Abstract [en]

    The switching behavior of a previously fabricated and tested SiC transistor is studied in Class-C amplifier in TCAD simulation. The transistor is simulated for pulse input signals in Class-C power amplifier. The simulated gain (dB), power density (W/mm) and power added efficiency (PAE%) at 500 MHz, 1, 2 and 3 GHz was studied using computational TCAD load pull simulation technique. A Maximum PAE of 77.8% at 500 MHz with 45.4 dB power gain and power density of 2.43 W/mm is achieved. This technique allows the prediction of switching response of the device for switching amplifier Classes (Class-C–F) before undertaking an expensive and time consuming device fabrication. The beauty of this technique is that, we need no matching and other lumped element networks for studying the large signal behavior of RF and microwave transistors.

    Keywords
    Pulse, Class-C, Power amplifier, New technique, Silicon carbide, MESFET
    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:liu:diva-13285 (URN)10.1016/j.sse.2007.09.022 (DOI)
    Available from: 2008-05-13 Created: 2008-05-13 Last updated: 2017-12-13Bibliographically approved
  • 3.
    Azam, Sher
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Jonsson, R.
    Janzén, Erik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Wahab, Qamar Ul
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Performance of SiC Microwave Transistors in Power Amplifiers2008In: Proc. of MRS Symposium on wide bandgap semiconductor electronics 8, 2008, p. 203-208Conference paper (Refereed)
    Abstract [en]

    The performance of SiC microwave power transistors is studied in fabricated class-AB power amplifiers and class-C switching power amplifier using physical structure of an enhanced version of previously fabricated and tested SiC MESFET. The results for pulse input in class-C at 1 GHz are; efficiency of 71.4 %, power density of 1.0 W/mm. The switching loss was 0.424 W/mm. The results for two class-AB power amplifiers are; the 30-100 MHz amplifier showed 45.6 dBm (∼ 36 W) output powers at P1dB, at 50 MHz. The power added efficiency (PAE) is 48 % together with 21 dB of power gain. The maximum output power at P1dB at 60 V drain bias and Vg= -8.5 V was 46.7 dBm (∼47 W). The typical results obtained in 200-500 MHz amplifier are; at 60 V drain bias the P1dB is 43.85 dBm (24 W) except at 300 MHz where only 41.8 dBm was obtained. The maximum out put power was 44.15 dBm (26 W) at 500 MHz corresponding to a power density of 5.2 W/mm. The PAE @ P1dB [%] at 500 MHz is 66 %.

  • 4.
    Azam, Sher
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Materials Science . Linköping University, The Institute of Technology.
    Jonsson, R.
    Swedish Defense Research Agency (FOI), SE-581 11, Linköping, Sweden.
    Svensson, Christer
    Linköping University, Department of Electrical Engineering, Electronic Devices. Linköping University, The Institute of Technology.
    Wahab, Qamar
    Linköping University, Department of Physics, Chemistry and Biology, Materials Science . Linköping University, The Institute of Technology.
    Broadband Power Amplifier performance of SiC MESFET and CostEffective SiGaN HEMTManuscript (preprint) (Other academic)
    Abstract [en]

    This paper describes the broadband power amplifier performance of two differentwide band gap technology transistors at 0.7 to 1.8 GHz using cost effective NitronexGaN HEMT on Silicon (Si) and Cree Silicon Carbide MESFET. The measured resultsfor GaN amplifier are; maximum output power at Vd = 28 V is 42.5 dBm (~18 W), amaximum PAE of 39 % and a maximum gain of 19.5 dB is obtained. The measuredmaximum output power for the SiC amplifier at Vd = 48 V was 41.3 dBm (~13.7 W),with a PAE of 32 % and a power gain above 10 dB. At a drain bias of Vd = 66 V at700 MHz for SiC MESFET amplifier the Pmax was 42.2 dBm (~16.6 W) with a PAE of34.4 %.

  • 5.
    Azam, Sher
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Materials Science . Linköping University, The Institute of Technology.
    Jonsson, R,
    Swedish Defense Research Agency (FOI), SE-581 11, Linköping, Sweden.
    Svensson, Christer
    Linköping University, Department of Electrical Engineering, Electronic Devices. Linköping University, The Institute of Technology.
    Wahab, Qamar
    Linköping University, Department of Physics, Chemistry and Biology, Materials Science . Linköping University, The Institute of Technology.
    High Power, High Efficiency SiC Power Amplifier for Phased ArrayRadar and VHF ApplicationsManuscript (preprint) (Other academic)
    Abstract [en]

    Wide band gap semiconductor (SiC & GaN) based power amplifiers offer severalsystem critical advantages such as less current leakage, better stability at high temperatureand easier impedance matching. This paper describes the design and fabrication of a singlestageclass-AB power amplifier for 30 to 100 MHz using SiC Schottky gate MetalSemiconductor Field Effect Transistor (MESFET). The maximum output power achieved is46.2 dBm (~42 W) at 50 V DC supply voltage at the drain. The maximum power gain is 21dB and a maximum PAE of 62 %. The amplifier performance was also checked at a higherdrain bias of 60 V at 50 MHz. At this bias voltage the maximum output power was 46.7dBm (~47 W) with a power gain of 21 dB and a maximum PAE of 42.7 %. An averageOIP3 of 54 dBm have been achieved for this amplifier.

  • 6.
    Azam, Sher
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Jonsson, R.
    Wahab, Qamar Ul
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    The limiting frontiers of maximum DC voltage at drain of SiC microwave power transistors in case of Class A power amplifiers2007In: International Semiconductor Device Research Symposium 2007 ISDRS-07,2007, IEEE , 2007Conference paper (Refereed)
    Abstract [en]

       

  • 7.
    Azam, Sher
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Jonsson, Rolf
    Fritzin, Jonas
    Linköping University, Department of Electrical Engineering, Electronic Devices. Linköping University, The Institute of Technology.
    Alvandpour, Atila
    Linköping University, Department of Electrical Engineering, Electronic Devices. Linköping University, The Institute of Technology.
    Wahab, Qamar
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    High Power, Single Stage SiGaN HEMT Class E Power Amplifier at GHz Frequencies2010In: IEEE International Bhurban Conference on Applied Sciences and Technology, IEEE , 2010Conference paper (Refereed)
  • 8.
    Azam, Sher
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Jonsson, Rolf
    Swedish Defense Research Agency (FOI), Box 1165, SE-581 11 Linkoping, Sweden.
    Fritzin, Jonas
    Linköping University, Department of Electrical Engineering, Electronic Devices. Linköping University, The Institute of Technology.
    Alvandpour, Atila
    Linköping University, Department of Electrical Engineering, Electronic Devices. Linköping University, The Institute of Technology.
    Wahab, Qamar
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    High Power, Single Stage SiGaN HEMT Class EPower Amplifier at GHz FrequenciesManuscript (preprint) (Other academic)
    Abstract [en]

    A high power single stage class E power amplifier is implemented with lumped elements at 0.89-1.02GHz using Silicon GaN High Electron Mobility Transistor as an active device. The maximum drain efficiency (DE) and power added efficiency (PAE) of 67 and 65 % respectively is obtained with a maximum output power of 42.2 dBm (~ 17 W) and amaximum power gain of 15 dB. We obtained good results at all measured frequencies.

  • 9.
    Azam, Sher
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Materials Science . Linköping University, The Institute of Technology.
    Jonsson, Rolf
    Swedish Defense Research Agency (FOI), Box 1165, SE-581 11 Linköping, Sweden.
    Wahab, Qamar
    Linköping University, Department of Physics, Chemistry and Biology, Materials Science . Linköping University, The Institute of Technology.
    Designing, Fabrication and Characterization of Power Amplifiers Based on 10-Watt SiC MESFET & GaN HEMT at Microwave Frequencies2008In: IEEE European Microwave Week, October 10-15, Amsterdam, The Netherlands, 2008, p. 444-447Conference paper (Refereed)
    Abstract [en]

    This paper describes the design, fabrication and measurement of two single-stage class-AB power amplifiers covering the frequency band from 0.7-1.8 GHz using a SiC MESFET and a GaN HEMT. The measured maximum output power for the SiC amplifier at Vd = 48 V was 41.3 dBm (~13.7 W), with a PAE of 32% and a power gain above 10 dB. At a drain bias of Vd= 66 V at 700 MHz the Pmax was 42.2 dBm (~16.6 W) with a PAE of 34.4%. The measured results for GaN amplifier are; maximum output power at Vd = 48 V is 40 dBm (~10 W), with a PAE of 34% and a power gain above 10 dB. The results for SiC amplifier are better than for GaN amplifier for the same 10-W transistor.

  • 10.
    Azam, Sher
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Materials Science . Linköping University, The Institute of Technology.
    Jonsson, Rolf
    Swedish Defense Research Agency (FOI), Box 1165, SE-581 11 Linköping, Sweden.
    Wahab, Qamar
    Linköping University, Department of Physics, Chemistry and Biology, Materials Science . Linköping University, The Institute of Technology.
    Single-stage, High Efficiency, 26-Watt power Amplifier using SiC LE-MESFET2006In: Microwave Conference, 2006. APMC 2006. Asia-Pacific December 12-15, 2006, p. 441-444Conference paper (Refereed)
    Abstract [en]

    This paper describes a single-stage 26 W negative feedback power amplifier, covering the frequency range 200-500 MHz using a 6 mm gate width SiC lateral epitaxy MESFET. Typical results at 50 V drain bias for the whole band are, around 22 dB power gain, around 43 dBm output power, minimum power added efficiency at P1 dB is 47% at 200 MHz and maximum 60% at 500 MHz and the IMD3 level at 10 dB back-off from P1 dB is below -45 dBc. The results at 60 V drain bias at 500 MHz are, 24.9 dB power gain, 44.15 dBm output power (26 W) and 66% PAE.

  • 11.
    Azam, Sher
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Materials Science . Linköping University, The Institute of Technology.
    Jonsson, Rolr
    Swedish Defense Research Agency (FOI), SE-581 11, Linköping, Sweden.
    Svensson, Christer
    Linköping University, Department of Electrical Engineering, Electronic Devices. Linköping University, The Institute of Technology.
    Wahab, Qamar
    Linköping University, Department of Physics, Chemistry and Biology, Materials Science . Linköping University, The Institute of Technology.
    Comparison of Two GaN TransistorsTechnology in Broadband Power AmplifiersManuscript (preprint) (Other academic)
    Abstract [en]

    This paper compares the performance of two different GaN technology transistors(GaN HEMT on Silicon substrate (PA1) and GaN on SiC PA2) utilized in two broadbandpower amplifiers at 0.7-1.8 GHz. The study explores the broadband power amplifierpotential of both GaN HEMT technologies for Phased Array Radar (PAR) and electronicswarfare (EW) systems. The measured maximum output power for PA1 is 42.5 dBm(~18 W) with a maximum PAE of 39 % and a gain of 19.5 dB. While the measuredmaximum output power for PA2 is 40 dBm with PAE of 35 % and a power gain slightlyabove 10 dB. We obtained high power, gain, wider band width and unconditionalstability without feedback for amplifier based on GaN HEMT technology fabricated on Sisubstrate.

  • 12.
    Azam, Sher
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Materials Science . Linköping University, The Institute of Technology.
    Svensson, Christer
    Linköping University, Department of Electrical Engineering, Electronic Devices. Linköping University, The Institute of Technology.
    Wahab, Qamar
    Linköping University, Department of Physics, Chemistry and Biology, Materials Science . Linköping University, The Institute of Technology.
    A New Load Pull TCAD Simulation Technique for Class D, E & FSwitching Characteristics of TransistorsManuscript (preprint) (Other academic)
    Abstract [en]

    We have further developed a computational load pull simulation technique inTCAD. It can be used to study the Class-D, E & F switching response of the transistors. Westudied our enhanced version of previously fabricated and tested SiC transistor. Thesimulated Gain (dB), Power density (W/mm), switching loss (W/mm) and power addedefficiency (PAE %) at 500 MHz were studied using this technique. A PAE of 84 % at500MHz with 26 dB Power gain and power density of 2.75 W/mm is achieved. Thistechnique allows the prediction of switching response of the device before undertaking anexpensive and time-consuming device fabrication. The beauty of this technique is that, weneed no matching and other lumped element networks to study the large signal switchingbehavior of RF and microwave transistors.

  • 13.
    Azam, Sher
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Materials Science . Linköping University, The Institute of Technology.
    Svensson, Christer
    Linköping University, Department of Electrical Engineering, Electronic Devices. Linköping University, The Institute of Technology.
    Wahab, Qamar
    Linköping University, Department of Physics, Chemistry and Biology, Materials Science . Linköping University, The Institute of Technology.
    Pulse Input Class-C Power Amplifier Response of SiC MESFET using Physical Transistor Structure in TCAD2008In: Solid-State Electronics, ISSN 0038-1101, E-ISSN 1879-2405, Vol. 52, no 5, p. 740-744Article in journal (Refereed)
    Abstract [en]

    The switching behavior of a previously fabricated and tested SiC transistor is studied in Class-C amplifier in TCAD simulation. The transistor is simulated for pulse input signals in Class-C power amplifier. The simulated gain (dB), power density (W/mm) and power added efficiency (PAE%) at 500 MHz, 1, 2 and 3 GHz was studied using computational TCAD load pull simulation technique. A Maximum PAE of 77.8% at 500 MHz with 45.4 dB power gain and power density of 2.43 W/mm is achieved. This technique allows the prediction of switching response of the device for switching amplifier Classes (Class-C–F) before undertaking an expensive and time consuming device fabrication. The beauty of this technique is that, we need no matching and other lumped element networks for studying the large signal behavior of RF and microwave transistors.

  • 14.
    Azam, Sher
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Svensson, Christer
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Electronic Devices.
    Wahab, Qamar Ul
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Designing of high efficiency power amplifier based on physical model of SiC MESFET in TCAD.2007In: International Bhurban conference on applied sciences technology.,2001, 2007Conference paper (Refereed)
    Abstract [en]

       

  • 15.
    Azam, Sher
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Svensson, Christer
    Linköping University, Department of Electrical Engineering, Electronic Devices. Linköping University, The Institute of Technology.
    Wahab, Qamar Ul
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Jonsson, R.
    Swedish Defence Research Agency.
    Comparison of Two GaN Transistor Technologies in Broadband Power Amplifiers2010In: MICROWAVE JOURNAL, ISSN 0192-6225, Vol. 53, no 4, p. 184-192Article in journal (Refereed)
    Abstract [en]

    This article compares the performance of two different GaN transistor technologies, GaN HEMT on silicon substrate (PA1) and GaN on SiC (PA2), utilized in two broadband power amplifiers operating at 0.7 to 1.8 GHz. The study explores the broadband power amplifier potential of both GaN HEMT technologies for phased-array radar (PAR) and electronic warfare (EW) systems. The measured maximum output power for PA1 is 42.5 dBm (18 W) with a maximum PAE of 66 percent and a gain of 19.5 dB. The measured maximum output power for PA2 is 40 dBm with a PAE of 37 percent and a power gain slightly above 10 dB. The high power gain, ME, wider bandwidth and unconditional stability was obtained without feedback for the amplifier based on GaN HEMT technology, fabricated on Si substrate.

  • 16.
    Kashif, Ahsan-Ullah
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Azam, Sher
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Svensson, Christer
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Electronic Devices.
    Wahab, Qamar Ul
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Flexible power amplifier designing form device to circuit level by computational load-pull simulation technique2008In: Microelectonics Technology and Devices - SBMicro 2008, Vol. 14, issue 1: J. Swart, S. Selberherr, A. Susin, J. Diniz, N. Morimoto, Pennington, New Jersey: Electrochemical Society , 2008, Vol. 14, p. 233-239Conference paper (Refereed)
    Abstract [en]

    Matchingnetwork is major issue in broadband power amplifiers due tothe fact that the transistor impedances are varying both withfrequency and signal level. Thus it is difficult to matchthese impedances both at the input and output stages. Thetunable matching networks are very demanding and desired for buildingflexible systems, but their accuracy depends on the transistor performanceunder the large signal operation. Computational load pull (CLP) simulationtechnique is a unique way to extract the impedances ofpower transistor at desired frequencies which make the design ofmatching network much easier for multiple bands power amplifiers. AnLDMOS transistor is studied and its optimum impedances are extractedat 1, 2 and 2.5 GHz. Through optimum impedance, thetunable matching networks can be easily design for broadband amplifiers.

  • 17.
    Kashif, Ahsan-Ullah
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Johansson, T.
    Infineon Technologies Nordic AB, SE-164 81 Kista, Sweden.
    Svensson, Christer
    Linköping University, Department of Electrical Engineering, Electronic Devices. Linköping University, The Institute of Technology.
    Azam, Sher
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Arnborg, T.
    Ericsson AB, SE-221 83 Lund, Sweden.
    Wahab, Qamar
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Influence of interface state charges on RF performance of LDMOS transistor2008In: Solid-State Electronics, ISSN 0038-1101, E-ISSN 1879-2405, Vol. 52, no 7, p. 1099-1105Article in journal (Refereed)
    Abstract [en]

    Si-LDMOS transistor is studied by TCAD simulation for improved RF performance. In LDMOS structure, a low-doped reduced surface field (RESURF) region is used to obtain high breakdown voltage, but it reduces the transistor RF performance due to high on-resistance. The interface charges between oxide and the RESURF region are studied and found to have a strong impact on the transistor performance both in DC and RF. The presence of excess interface state charges at the RESURF region results not only higher DC drain current but also improved RF performance in terms of power, gain and efficiency. The most important achievement is the enhancement of operating frequency and RF output power is obtained well above 1 W/mm up to 4 GHz.

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