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Efficiency ehancement of W-CDMA base-station envelope tracking power amplifiers via load modulation
Jeong, Jinho,Asbeck, Peter Wiley Subscription Services, Inc., A Wiley Company 2007 MICROWAVE AND OPTICAL TECHNOLOGY LETTERS Vol.49 No.8
<P>Load impedance modulation and gate bias control were investigated to improve the performance of W-CDMA base-station envelope tracking amplifiers by means of simulations based on the measured data of a 10-W GaAs FET power amplifier. It is shown that adapting the load impedance along with the drain bias voltage can effectively improve the average efficiency of envelope tracking amplifier. The improvement becomes more apparent in the operating regime of power back-off. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1954–1957, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22566</P>
Chen, Han-Ping,Yuan, Yu,Yu, Bo,Ahn, Jaesoo,McIntyre, Paul C.,Asbeck, Peter M.,Rodwell, Mark J. W.,Taur, Yuan IEEE 2012 IEEE transactions on electron devices Vol.59 No.9
<P>This paper presents a detailed analysis of the multifrequency capacitance–voltage and conductance–voltage data of <TEX>$\hbox{Al}_{2}\hbox{O}_{3}/\hbox{n-InGaAs}$ </TEX> MOS capacitors. It is shown that the widely varied frequency dependence of the data from depletion to inversion can be fitted to various regional equivalent circuits derived from the full interface-state model. In certain regions, incorporating bulk-oxide traps in the interface-state model enables better fitting of data. By calibrating the model with experimental data, the interface-state density and the trap time constants are extracted as functions of energy in the bandgap, from which the stretch-out of gate voltage is determined. It is concluded that the commonly observed decrease of the 1-kHz capacitance toward stronger inversion is due to the increasing time constant for traps to capture majority carriers at the inverted surface.</P>
Design of a 4-W Envelope Tracking Power Amplifier With More Than One Octave Carrier Bandwidth
Yan, J. J.,Chin Hsia,Kimball, D. F.,Asbeck, P. M. IEEE 2012 IEEE journal of solid-state circuits Vol.47 No.10
<P>This paper presents a high-efficiency broadband envelope-tracking power amplifier with operation at carrier frequencies from 500 to 1750 MHz. The RF power amplifier (RFPA) is provided by a single-chip gallium-nitride (GaN) integrated circuit (IC) whose design included a broadband output match achieved by operating directly into a load resistance of 50 Ω and broadband input match achieved using a feedback network. Under single-tone excitation, the Class-AB GaN PA IC provides output power above 12 W with greater than 50% drain efficiency and more than 10-dB gain at 40-V drain bias. When placed in envelope tracking configuration, using a representative WCDMA modulated signal with 4-MHz bandwidth and 6.6-dB peak-to-average power ratio, the ET PA achieved 4 W of average output power at its peak average drain efficiency of 31% at 752 MHz (including the power dissipation of the envelope modulator). The RFPA individually was measured to have an average drain efficiency of 58.5% for the WCDMA signal. Across the 500-1750-MHz band, using the WCDMA signal, greater than 25% average drain efficiency with more than 10 dB of gain was measured.</P>
High Power Digitally-Controlled SOI CMOS Attenuator With Wide Attenuation Range
Jinho Jeong,Pornpromlikit, Sataporn,Scuderi, Antonino,Presti, Calogero,Asbeck, Peter IEEE 2011 IEEE microwave and wireless components letters Vol.21 No.8
<P>An attenuator is presented in a 0.13 μm silicon-on-insulator (SOI) CMOS technology, to be used for power control of RF wireless transmitters. The design is based on a T-network consisting of two series switches and 63 shunt switches. A gate switching technique is utilized in the series switches for high power handling and high isolation. Measurements at 1.88 GHz show that the minimum insertion loss is as low as 0.6 dB and maximum attenuation is 55.3 dB with worst input return loss of 8.1 dB. The attenuation can be digitally controlled in steps of around 1 dB. The 1 dB gain compression point is as high as 21.0 dBm in the through mode.</P>
Myoungbo Kwak,Kimball, D. F.,Presti, C. D.,Scuderi, A.,Santagati, C.,Yan, J. J.,Asbeck, P. M.,Larson, L. E. IEEE 2012 IEEE transactions on microwave theory and techniqu Vol.60 No.6
<P>A high-performance bipolar-CMOS-DMOS (BCD) monolithic envelope amplifier for micro-base-station power amplifiers (PAs) is presented. Measurement of the BCD high-voltage (<I>V</I><SUB>DD</SUB> = 15 V) envelope amplifier shows an efficiency of 72% using 7.7-dB peak-to-average ratio WCDMA input signals at an average envelope amplifier output power above 3 W. A WCDMA envelope-tracking RF PA at 2.14 GHz, including a GaN field-effect transistor RF stage, has an overall drain efficiency above 51%, with a normalized power root-mean-square error below 1.2% and an adjacent channel leakage ratio of -49 dBc at 5-MHz offset using memory-effect mitigation digital pre-distortion, at an average output power above 2 W and a gain of 10 dB.</P>
Efficiency Enhancement of mm-Wave Power Amplifiers Using Envelope Tracking
Yan, J J,Presti, C D,Kimball, D F,Young-Pyo Hong,Chin Hsia,Asbeck, P M,Schellenberg, J IEEE 2011 IEEE microwave and wireless components letters Vol.21 No.3
<P>This letter presents a 44 GHz GaAs MMIC-based power amplifier (PA) which uses envelope tracking (ET) techniques for efficiency enhancement. Digital pre-distortion (DPD) is also employed to achieve high linearity. For a 7.6 dB PAPR 64QAM 20 MHz bandwidth signal (data rate 120 Mb/s) at an output power of 23.8 dBm, the measured EVM was 2.0% and ACPR1 was better than -40 dBc. Power efficiency enhancement of more than 5.7 times for the final MMIC stage (from 1.22% to 7%) was measured, using an external drain modulator. To the authors' best knowledge, this is the first time envelope tracking has been applied to PAs in the millimeter wave regime.</P>