Preface. About the Authors. Acknowledgments. 1 Power Amplifier Fundamentals. 1.1 Introduction. 1.2 Definition of Power Amplifier Parameters. 1.3 Distortion Parameters. 1.4 Power Match Condition. 1.5 Class of Operation. 1.6 Overview of Semiconductors for PAs. 1.7 Devices for PA. 1.8 Appendix: Demonstration of Useful Relationships. 1.9 References. 2 Power Amplifier Design. 2.1 Introduction. 2.2 Design Flow. 2.3 Simplified Approaches. 2.4 The Tuned Load Amplifier. 2.5 Sample Design of a Tuned Load PA. 2.6 References. 3 Nonlinear Analysis for Power Amplifiers. 3.1 Introduction. 3.2 Linear vs. Nonlinear Circuits. 3.3 Time Domain Integration. 3.4 Example. 3.5 Solution by Series Expansion. 3.6 The Volterra Series. 3.7 The Fourier Series. 3.8 The Harmonic Balance. 3.9 Envelope Analysis. 3.10 Spectral Balance. 3.11 Large Signal Stability Issue. 3.12 References. 4 Load Pull. 4.1 Introduction. 4.2 Passive Source/Load Pull Measurement Systems. 4.3 Active Source/Load Pull Measurement Systems. 4.4 Measurement Test-sets. 4.5 Advanced Load Pull Measurements. 4.6 Source/Load Pull Characterization. 4.7 Determination of Optimum Load Condition. 4.8 Appendix: Construction of Simplified Load Pull Contours through Linear Simulations. 4.9 References. 5 High Efficiency PA Design Theory. 5.1 Introduction. 5.2 Power Balance in a PA. 5.3 Ideal Approaches. 5.4 High Frequency Harmonic Tuning Approaches. 5.5 High Frequency Third Harmonic Tuned (Class F). 5.6 High Frequency Second Harmonic Tuned. 5.7 High Frequency Second and Third Harmonic Tuned. 5.8 Design by Harmonic Tuning. 5.9 Final Remarks. 5.10 References. 6 Switched Amplifiers. 6.1 Introduction. 6.2 The Ideal Class E Amplifier. 6.3 Class E Behavioural Analysis. 6.4 Low Frequency Class E Amplifier Design. 6.5 Class E Amplifier Design with 50# Duty-cycle. 6.6 Examples of High Frequency Class E Amplifiers. 6.7 Class E vs. Harmonic Tuned. 6.8 Class E Final Remarks. 6.9 Appendix: Demonstration of Useful Relationships. 6.10 References. 7 High Frequency Class F Power Amplifiers. 7.1 Introduction. 7.2 Class F Description Based on Voltage Wave-shaping. 7.3 High Frequency Class F Amplifiers. 7.4 Bias Level Selection. 7.5 Class F Output Matching Network Design. 7.6 Class F Design Examples. 7.7 References. 8 High Frequency Harmonic Tuned Power Amplifiers. 8.1 Introduction. 8.2 Theory of Harmonic Tuned PA Design. 8.3 Input Device Nonlinear Phenomena: Theoretical Analysis. 8.4 Input Device Nonlinear Phenomena: Experimental Results. 8.5 Output Device Nonlinear Phenomena. 8.6 Design of a Second HT Power Amplifier. 8.7 Design of a Second and Third HT Power Amplifier. 8.8 Example of 2nd HT GaN PA. 8.9 Final Remarks. 8.10 References. 9 High Linearity in Efficient Power Amplifiers. 9.1 Introduction. 9.2 Systems Classification. 9.3 Linearity Issue. 9.4 Bias Point Influence on IMD. 9.5 Harmonic Loading Effects on IMD. 9.6 Appendix: Volterra Analysis Example. 9.7 References. 10 Power Combining. 10.1 Introduction. 10.2 Device Scaling Properties. 10.3 Power Budget. 10.4 Power Combiner Classification. 10.5 The T-junction Power Divider. 10.6 Wilkinson Combiner. 10.7 The Quadrature (90 ) Hybrid. 10.8 The 180 Hybrid (Ring Coupler or Rat-race). 10.9 Bus-bar Combiner. 10.10 Other Planar Combiners. 10.11 Corporate Combiners. 10.12 Resonating Planar Combiners. 10.13 Graceful Degradation. 10.14 Matching Properties of Combined PAs. 10.15 Unbalance Issue in Hybrid Combiners. 10.16 Appendix: Basic Properties of Three-port Networks. 10.17 References. 11 The Doherty Power Amplifier. 11.1 Introduction. 11.2 Doherty's Idea. 11.3 The Classical Doherty Configuration. 11.4 The 'AB-C' Doherty Amplifier Analysis. 11.5 Power Splitter Sizing. 11.6 Evaluation of the Gain in a Doherty Amplifier. 11.7 Design Example. 11.8 Advanced Solutions. 11.9 References. Index.

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High Efficiency RF and Microwave Solid State Power Amplifiers

Trapping is one of the most deleterious effects that limit performance and reliability in GaN HEMTs. In this paper, we present a methodology to study trapping characteristics in GaN HEMTs that is based on current-transient measurements. Its uniqueness is that it is amenable to integration with electrical stress experiments in long-term reliability studies. We present the details of the measurement and analysis procedures. With this method, we have investigated the trapping and detrapping dynamics of GaN HEMTs. In particular, we examined layer location, energy level, and trapping/detrapping time constants of dominant traps. We have identified several traps inside the AlGaN barrier layer or at the surface close to the gate edge and in the GaN buffer.

http://www.mtl.mit.edu/~alamo/pdf/2011/RJ-128.pdf

A Current-Transient Methodology for Trap Analysis for GaN High Electron Mobility Transistors

Recent advances in wide bandgap semiconductor biological and gas sensors

A packaged light emitting device. The device includes a substrate member comprising a surface region and one or more light emitting diode devices overlying the surface region. In a specific embodiment, at least one of the light emitting diode device is fabricated on a semipolar or nonpolar GaN containing substrate. The one or more light emitting diode devices are fabricated on the semipolar or nonpolar GaN containing substrate emits substantially polarized emission of one or more first wavelengths. At least at least one of the light emitting diode devices comprise a quantum well region, which is characterized by an electron wave function and a hole wave function. In a specific embodiment, the electron wave function and the hole wave function are substantially overlapped within a predetermined spatial region of the quantum well region. In a specific embodiment, the device has a thickness of one or more entities formed overlying the one or more light emitting diode devices. The one or more entities are excited by the substantially polarized emission and emitting electromagnetic radiation of one or more second wavelengths.

White light devices using non-polar or semipolar gallium containing materials and phosphors

The present invention is directed to display technologies. More specifically, various embodiments of the present invention provide projection display systems where one or more laser diodes are used as light source for illustrating images. In one set of embodiments, the present invention provides projector systems that utilize blue and/or green laser fabricated using gallium nitride containing material. In another set of embodiments, the present invention provides projection systems having digital lighting processing engines illuminated by blue and/or green laser devices. In one embodiment, the present invention provides a 3D display system. There are other embodiments as well.

Laser based display method and system

Bulk GaN crystal growth by the high-pressure ammonothermal method

We have fabricated SiC metal semiconductor field effect transistors (MESFETs) with more than 60 W of output power at 450 MHz from single 21.6 mm gate periphery devices (2.9 W/mm) and 27 W of output power at 3 GHz from single 14.4 mm SiC MESFET devices (1.9 W/mm). We have also demonstrated more than 6.7 W/mm CW power from 400 μm GaN/AlGaN high electron mobility transistors devices for X band (10 GHz) applications. These excellent device performances have been attributed to the improved substrate and epitaxial films quality, optimized device thermal management, and enhanced device fabrication technologies. The substrates and epitaxial films from different sources were compared and some showed significant less SiC substrate micropipes confirmed by X-ray topography and epitaxial defects characterized by optical defect mapping.

Microwave power SiC MESFETs and GaN HEMTs

1.5 mm gate periphery AlGaN/GaN HEMTs were fabricated and tested. 9.2 W/mm (total 13.8 W) power was obtained at 10 GHz under pulsed conditions without active cooling. The pulse width was 50 /spl mu/s with 5% duty cycle. This is the state-of-the-art power density demonstrated from the similar size devices. The device was biased at up to 55 V drain bias. At the above pulse conditions and drain bias, the simulated maximum junction temperature was 170/spl deg/C, indicating that device performance was limited by the self-heating effect.

E.B. Kaminsky

Papers

Bulk GaN crystal growth by the high-pressure ammonothermal method

Microwave power SiC MESFETs and GaN HEMTs

9.2 W/mm (13.8 W) AlGaN/GaN HEMTs at 10 GHz and 55 V drain bias

Cathodoluminescence mapping and selective etching of defects in bulk GaN

Identification of subsurface damage in freestanding HVPE GaN substrates and its influence on epitaxial growth of GaN epilayers