Sat, 19 Jul 2008 03:10:11 BST CiteULike: dcastro's amplifier http://www.citeulike.org/user/dcastro/tag/amplifier CiteULike.org en-gb Copyright © 2004-2008 citeulike.org http://www.citeulike.org/user/dcastro/article/3015404 <i>Microwave Conference, 2006. APMC 2006. Asia-Pacific (2006), pp. 953-956.</i><br /><br />The trend of microwave circuits has been toward highly integrated systems. Most design tools for circuits are based on the fundamental circuit theory using the S-matrix combined with the harmonic-balance method. Consequently, the electromagnetic effect is ignored or approximated at best. Therefore, the extended finite-difference time-domain (FDTD) method combined with the equivalent circuit simulation had been presented. However, it takes very long times to analyze any circuits. In this paper, we propose a novel extended FDTD method to reduce calculation resources. We investigate its efficiency to compare with the conventional extended FDTD method or measurements, consequently, it is confirmed that the proposal method is required calculation resources less than 10% compared with the conventional method. We also show that the proposal method is able to analyze characteristics of the active integrated antenna(AIA) which are practicably impossible to analyze by using the conventional method. A novel extended FDTD method for the analysis of the active integrated circuit and antenna mounted non- linear devices N Kawashima K Fujimori M Sanagi S Nogi doi:10.1109/APMC.2006.4429570 Microwave Conference, 2006. APMC 2006. Asia-Pacific (2006), pp. 953-956. 2008-07-17T19:46:55-00:00 2006 Microwave Conference, 2006. APMC 2006. Asia-Pacific 953 956 active amplifier analysis antenna fdtd http://www.citeulike.org/user/dcastro/article/2959193 <i>Broadcasting, IEEE Transactions on, Vol. 44, No. 1. (1998), pp. 106-114.</i><br /><br />The activities of the current European RACE and ACTS projects have led to an increasing interest in OFDM (orthogonal frequency division multiplexing) as a means of combating impulsive noise and multipath effects and making fuller use of the available bandwidth of the system. This paper analyses the performance of OFDM signals in amplifier nonlinearity. In particular, bit error rate (BER) degradation as a result of amplitude limiting or clipping are analysed. In the presence of both nonlinear distortion and additive Gaussian noise, optimized output power back off is provided to balance the requirements of minimum BER and power amplifier efficiency. For this purpose, an OFDM system has been built using the SPW (Signal Processing Worksystem) simulator OFDM performance in amplifier nonlinearity S Merchan AG Armada JL Garcia doi:10.1109/11.713060 Broadcasting, IEEE Transactions on, Vol. 44, No. 1. (1998), pp. 106-114. 2008-07-03T13:20:11-00:00 1998 Broadcasting, IEEE Transactions on 44 1 106 114 amplifier nonlinear ofdm http://www.citeulike.org/user/dcastro/article/2959195 <i>Communications, IEEE Transactions on, Vol. 50, No. 3. (2002), pp. 462-472.</i><br /><br />The orthogonal frequency-division multiplexing (OFDM) modulation format has been proposed in Europe as the standard for broadcasting both audio and television digital signals and for wide-band wireless communication systems (e.g., HIPERLAN II). The performance of the OFDM scheme is severely affected by the nonlinearity of the high-power amplifier at the transmitter end and by the phase noise of the oscillators. In this paper, we investigate the joint effects induced on the OFDM signal by the amplifier nonlinearity and by the phase noise. An accurate statistical description of each contribution to the signal distortion is provided. Theoretical results show perfect agreement with those obtained by simulation and they can be used to derive the OFDM system performance, without the need to run extensive simulations M-QAM-OFDM system performance in the presence of a nonlinear amplifier and phase noise E Costa S Pupolin doi:10.1109/26.990908 Communications, IEEE Transactions on, Vol. 50, No. 3. (2002), pp. 462-472. 2008-07-03T13:20:23-00:00 2002 Communications, IEEE Transactions on 50 3 462 472 amplifier nonlinear ofdm http://www.citeulike.org/user/dcastro/article/2959196 <i>Broadcasting, IEEE Transactions on, Vol. 47, No. 2. (2001), pp. 123-136.</i><br /><br />The paper analyzes the performance of the downlink channel of a multimedia interactive service system which transmits the desired information by the frequency multiplexing of several OFDM signals compliant with the DVB-T standard. The effects of the nonlinear distortions introduced by a high power amplifier on the system performance are evaluated both in terms of the bit error rate (BER) degradation in AWGN channels and of the spectral regrowth. The performance comparison to the case of a single DVB-T signal as well as the benefits of an ideal predistortion is also considered by comparing analytical results to computer simulations Effects of HPA nonlinearity on frequency multiplexed OFDM signals P Banelli G Baruffa S Cacopardi doi:10.1109/11.948265 Broadcasting, IEEE Transactions on, Vol. 47, No. 2. (2001), pp. 123-136. 2008-07-03T13:20:27-00:00 2001 Broadcasting, IEEE Transactions on 47 2 123 136 amplifier nonlinear ofdm http://www.citeulike.org/user/dcastro/article/2959198 <i>Radio and Wireless Conference, 2000. RAWCON 2000. 2000 IEEE (2000), pp. 91-94.</i><br /><br />New OFDM-based WLAN standards target wireless communications in the 5 GHz band for consumer multimedia applications. Given the high data rates with required low bit error rates, and given the nature of the OFDM signal, a conservative analysis of the front-end requirements lead to severe, over dimensioned specifications. Such a design would never meet this market, by necessity low-cost and low-power. To extract more optimal front-end specifications, we assess the BER performance of the complete WLAN-OFDM link. As a result, we first show that the transmitted symbols' word-length can be restricted to 8-bit and the normalized crest factor digitally limited at baseband to 4. Then we show that the power amplifier can operate with only 5.4 dB back-off between the average input power and the input-referred P_ldB. Finally, we quantify in terms of implementation loss the influence of the I/Q imbalance and of the frequency synthesizer phase noise Impact of front-end non-idealities on bit error rate performance of WLAN-OFDM transceivers B Come R Ness S Donnay L Van der Perre W Eberle P Wambacq M Engels I Bolsens doi:10.1109/RAWCON.2000.881863 Radio and Wireless Conference, 2000. RAWCON 2000. 2000 IEEE (2000), pp. 91-94. 2008-07-03T13:20:35-00:00 2000 Radio and Wireless Conference, 2000. RAWCON 2000. 2000 IEEE 91 94 amplifier nonlinear ofdm http://www.citeulike.org/user/dcastro/article/2958633 <i>Communications Letters, IEEE, Vol. 3, No. 2. (1999), pp. 37-39.</i><br /><br />The power spectral density of an orthogonal frequency-division multiplexing (OFDM) signal after a saturated high-power amplifier (HPA) is analytically derived. The distortion of the HPA-processed OFDM signal is defined, and its power spectrum is computed. The spectra of the signal and of the distortion are used to get an accurate estimate of the bit-error rate of an OFDM transmission system and to derive compensation at the receiver, which leads to performance improvement Impact of amplifier nonlinearities on OFDM transmission system performance E Costa M Midrio S Pupolin doi:10.1109/4234.749355 Communications Letters, IEEE, Vol. 3, No. 2. (1999), pp. 37-39. 2008-07-03T10:23:31-00:00 1999 Communications Letters, IEEE 3 2 37 39 amplifier nonlinear ofdm http://www.citeulike.org/user/dcastro/article/2933323 <i>Microwave Symposium Digest, 2004 IEEE MTT-S International, Vol. 3 (2004), pp. 1543-1546 Vol.3.</i><br /><br />This paper presents a power amplifier based on envelope tracking (ET) with application to the WLAN 802.11g system. Baseband pre-distortion is implemented to improve the linearity. A high-efficiency wide-bandwidth envelope amplifier and a GaAs MESFET class AB RFPA are designed and implemented for the system. An overall system drain efficiency of 30% is obtained for an OFDM output power of 20 dBm at 2.4GHz. Envelope tracking power amplifier with pre-distortion linearization for WLAN 802.11g Feipeng Wang A Ojo D Kimball P Asbeck L Larson doi:10.1109/MWSYM.2004.1338872 Microwave Symposium Digest, 2004 IEEE MTT-S International, Vol. 3 (2004), pp. 1543-1546 Vol.3. 2008-06-27T10:39:57-00:00 2004 Microwave Symposium Digest, 2004 IEEE MTT-S International 3 1543 1546 Vol.3 amplifier envelope ofdm papr power wifi http://www.citeulike.org/user/dcastro/article/2933305 <i>Microwave Theory and Techniques, IEEE Transactions on, Vol. 47, No. 8. (1999), pp. 1461-1466.</i><br /><br />This paper introduces a figure-of-merit to investigate tradeoffs between amplifiers and modulation waveforms in complex digital communications systems. Class-AB amplifiers are investigated with a variety of modulation schemes to better understand the relations between amplifier efficiency, amplifier distortion, signal in-band and adjacent channel interference, and power consumption. The goal is to better understand the tradeoffs needed to design low-energy communications systems Nonlinear amplifier effects in communications systems Cheng-Po Liang Je-Hong Jong WE Stark JR East doi:10.1109/22.780395 Microwave Theory and Techniques, IEEE Transactions on, Vol. 47, No. 8. (1999), pp. 1461-1466. 2008-06-27T10:32:47-00:00 1999 Microwave Theory and Techniques, IEEE Transactions on 47 8 1461 1466 amplifier comunication nonlinear http://www.citeulike.org/user/dcastro/article/2839866 <i>Microwave Symposium Digest, 2005 IEEE MTT-S International (2005), 4 pp..</i><br /><br />A class-F power amplifier at 2.4GHz using a novel harmonic tuner based on a composite right/left handed (CRLH) transmission line (TL) is proposed and experimentally tested. Two structures are presented. One structure uses one open CRLH-TL stub to suppress 2nd, 3rd harmonics and the fundamental frequency is matched to 50/spl Omega/. The other structure uses two open CRLH-TL stubs in order to suppress 2nd, 3rd, 4th harmonics and the fundamental frequency is matched to specific impedance. The structure proposed is used to design a class-F power amplifier. A maximum drain efficiency of 64% is obtained. Class-F power amplifier using a multi-frequency composite right/left-handed transmission line harmonic tuner A Dupuy KMKH Leong T Itoh doi:10.1109/MWSYM.2005.1517142 Microwave Symposium Digest, 2005 IEEE MTT-S International (2005), 4 pp.. 2008-05-28T06:59:29-00:00 2005 Microwave Symposium Digest, 2005 IEEE MTT-S International 4 pp. amplifier crlh metamaterial power http://www.citeulike.org/user/dcastro/article/2801444 <i>Microwave Symposium Digest, 1997., IEEE MTT-S International, Vol. 2 (1997), pp. 687-690 vol.2.</i><br /><br />A high efficiency class F power amplifier integrated with a circular sector microstrip antenna is reported. To obtain the class F operation, the second and third harmonics are shaped through the input impedance of the antenna. At the operating frequency of 2.55 GHz, a power added efficiency of 63% is demonstrated Class F power amplifier integrated with circular sector microstrip antenna V Radisic Yongxi Qian T Itoh doi:10.1109/MWSYM.1997.602884 Microwave Symposium Digest, 1997., IEEE MTT-S International, Vol. 2 (1997), pp. 687-690 vol.2. 2008-05-15T12:09:43-00:00 1997 Microwave Symposium Digest, 1997., IEEE MTT-S International 2 687 690 vol.2 amplifier antenna circular integrated microstrip power http://www.citeulike.org/user/dcastro/article/2801359 <i>Microwave Symposium Digest, 1991., IEEE MTT-S International (1991), pp. 1261-1264 vol.3.</i><br /><br />Prototypes of quasi-optical transmitter components (an oscillator and an amplifier) using FETs as one-port devices are reported. By using a lost antenna and microstrip-to-slotline transition, the circuit portion and the antenna are separated on different interfaces. About 1% tuning range (100 MHz around 9.4 GHz) of the oscillation frequency on the negative resistance oscillator and about 2% locking range (200 MHz around 9.3 GHz) of locking frequency on the negative resistance amplifier were obtained by controlling applied DC voltages. The radiation patterns are reported A layered negative resistance amplifier and oscillator using a FET and a slot antenna S Kawasaki T Itoh doi:10.1109/MWSYM.1991.147251 Microwave Symposium Digest, 1991., IEEE MTT-S International (1991), pp. 1261-1264 vol.3. 2008-05-15T11:28:57-00:00 1991 Microwave Symposium Digest, 1991., IEEE MTT-S International 1261 1264 vol.3 amplifier antenna fet oscillator http://www.citeulike.org/user/dcastro/article/2786601 <i>Microwave Theory and Techniques, IEEE Transactions on, Vol. 82, No. 11. (1982), pp. 1900-1907.</i><br /><br />The noise figure, the gain, and the reflection coefficients of lossy match amplifiers and their dependence on circuit elements are studied. Theoretical results are supported by measured data taken on a two-stage unit. In addition, the performance characteristics of a 100-8800 MHz four-stage lossy match amplifier are discussed. The unit exhibits 23.3 +- 1.1 dB of gain over the nearly 6-1/2 octaves. Its maximum noise figure is 10.9 dB from 100-8800 MHz and 6.6 dB from 2000-8000 MHz. The amplifier's overall circuit dimensions are 10 X 5.7 mm.. On Design and Performance of Lossy Match GaAs MESFET Amplifiers Microwave Theory and Techniques, IEEE Transactions on, Vol. 82, No. 11. (1982), pp. 1900-1907. 2008-05-12T06:26:46-00:00 1982 Microwave Theory and Techniques, IEEE Transactions on 82 11 1900 1907 amplifier equalization power resistive http://www.citeulike.org/user/dcastro/article/2782935 <i>Electronics Letters, Vol. 28, No. 22. (1992), pp. 2063-2064.</i><br /><br />A new simple model for the signal and noise properties of a microwave FET or HEMT avoids the need for any explicit correlation between gate and drain noise sources by distributing the drain-to-gate capacitance and the drain noise source along the conducting channel. The new model applied to a commercial HEMT chip demonstrates a very good fit to measured scattering and noise parameter data Distributed channel model for HEMT signal and noise parameters P Gardner DK Paul Electronics Letters, Vol. 28, No. 22. (1992), pp. 2063-2064. 2008-05-10T14:14:37-00:00 1992 Electronics Letters 28 22 2063 2064 amplifier channel distributed microwave model noise parameter signal http://www.citeulike.org/user/dcastro/article/2782068 <i>Satellite Communications - ECSC-3, 1993., 3rd European Conference on (1993), pp. 394-398.</i><br /><br />Power amplifier nonlinearity limits the performance of communication systems, both on the ground and in space, through undesirable effects such as crosstalk, intermodulation distortion and reduced signal to noise ratio in the presence of multiple signals. Feedforward linearization is a promising technique for improving the performance of power amplifiers particularly in millimetre wave applications where the power output of currently available devices is limited Feedforward linearization of microwave amplifiers K Konstantinou P Gardner DK Paul Satellite Communications - ECSC-3, 1993., 3rd European Conference on (1993), pp. 394-398. 2008-05-10T00:03:29-00:00 1993 Satellite Communications - ECSC-3, 1993., 3rd European Conference on 394 398 amplifier linearization power http://www.citeulike.org/user/dcastro/article/2782067 <i>Microwave Magazine, IEEE, Vol. 2, No. 4. (2001), pp. 37-49.</i><br /><br />This article discusses techniques for the cancellation of distortion (linearization) in power amplifiers. Different methods of linearization are introduced and compared. The linearization of solid-state power amplifiers (SSPAs), traveling-wave tube amplifiers (TWTAs) and klystron power amplifiers (KPAs) are considered. Although the focus of this article is on power amplifiers, many of the techniques are applicable to other components such as mixers, low-noise amplifiers, and even photonic components, such as lasers and optical modulators Linearization: reducing distortion in power amplifiers A Katz doi:10.1109/6668.969934 Microwave Magazine, IEEE, Vol. 2, No. 4. (2001), pp. 37-49. 2008-05-10T00:03:27-00:00 2001 Microwave Magazine, IEEE 2 4 37 49 amplifier linearization power http://www.citeulike.org/user/dcastro/article/2782044 <i>Microwave Conference, 2000 Asia-Pacific (2000), pp. 863-866.</i><br /><br />When employing conditionally stable transistors in microwave amplifier design, it is impossible to have both parts perfectly matched. One can easily design for a perfect match at one of the parts, but the resulting mismatch at the remaining part may be unacceptable. Through trial and error using graphical methods, the designer may trade-off the perfect part match for improved match at the other part. In this paper, we propose a systematic approach whereby the maximisation of an objective function results in maximum gain and part match, for given stability safety margins Optimum design of small-signal microwave amplifiers with specified stability safety margin KW Eccleston doi:10.1109/APMC.2000.925966 Microwave Conference, 2000 Asia-Pacific (2000), pp. 863-866. 2008-05-09T23:55:47-00:00 2000 Microwave Conference, 2000 Asia-Pacific 863 866 amplifier design microwave http://www.citeulike.org/user/dcastro/article/2782041 <i>Microwave Theory and Techniques, IEEE Transactions on, Vol. 50, No. 3. (2002), pp. 814-826.</i><br /><br />The generation of RF/microwave power is required not only in wireless communications, but also in applications such as jamming, imaging, RF heating, and miniature dc/dc converters. Each application has its own unique requirements for frequency, bandwidth, load, power, efficiency, linearity, and cost. RF power is generated by a wide variety of techniques, implementations, and active devices. Power amplifiers are incorporated into transmitters in a similarly wide variety of architectures, including linear, Kalm, envelope tracking, outphasing, and Doherty. Linearity can be improved through techniques such as feedback, feedforward, and predistortion Power amplifiers and transmitters for RF and microwave FH Raab P Asbeck S Cripps PB Kenington ZB Popovic N Pothecary JF Sevic NO Sokal doi:10.1109/22.989965 Microwave Theory and Techniques, IEEE Transactions on, Vol. 50, No. 3. (2002), pp. 814-826. 2008-05-09T23:54:52-00:00 2002 Microwave Theory and Techniques, IEEE Transactions on 50 3 814 826 amplifier microwave power rf transmitter http://www.citeulike.org/user/dcastro/article/2782035 <i>Microwave Conference, 1999 Asia Pacific, Vol. 1 (1999), pp. 1-4 vol.1.</i><br /><br />In low noise microwave amplifier design, particularly when using conditionally stable transistors, it is impossible to simultaneously achieve maximum gain, minimum noise figure and maximum port match. Hence it is necessary to trade-off these performance parameters which is usually accomplished with the aid of stability, gain, noise figure and mismatch (or VSWR) circles described on the reflection coefficient planes. However, use of these graphical aids is often subjective, necessitating final optimisation using circuit design software. In this paper, we propose a different approach whereby the functional behaviour of two objective functions involving gain, noise figure and port mismatch are described as functions of the stability safety margin. This approach leads to an optimum design without requiring sophisticated optimisation algorithms and includes stability safety margin as a design parameter Stability safety margin based design of low noise microwave amplifiers KW Eccleston doi:10.1109/APMC.1999.828033 Microwave Conference, 1999 Asia Pacific, Vol. 1 (1999), pp. 1-4 vol.1. 2008-05-09T23:51:31-00:00 1999 Microwave Conference, 1999 Asia Pacific 1 1 4 vol.1 amplifier low noise http://www.citeulike.org/user/dcastro/article/2782026 <i>Microwave Theory and Techniques, IEEE Transactions on, Vol. 45, No. 5. (1997), pp. 580-586.</i><br /><br />A new method, using the noise matrix approach, has been developed for determining the optimum reactive terminations for a transistor employed as a low-noise negative-resistance element in a reflection-mode amplifier. This new method corroborates the less efficient graphical method the authors reported earlier. It is established theoretically and demonstrated numerically that the optimum noise measure of a transistor used in a reflection-mode amplifier is independent of the choice of active terminal and is identical to the optimum noise measure of the same transistor when used in a conventional transmission-mode amplifier Optimum noise measure configurations for transistor negative resistance amplifiers P Gardner DK Paul doi:10.1109/22.575572 Microwave Theory and Techniques, IEEE Transactions on, Vol. 45, No. 5. (1997), pp. 580-586. 2008-05-09T23:50:36-00:00 1997 Microwave Theory and Techniques, IEEE Transactions on 45 5 580 586 amplifier measurement noise http://www.citeulike.org/user/dcastro/article/2782021 <i>Microwave and Wireless Components Letters, IEEE, Vol. 12, No. 11. (2002), pp. 421-423.</i><br /><br />The authors experimentally investigate and discuss the effects of output harmonic termination on power added efficiency (PAE) and output power of an AlGaN/GaN high electron mobility transistor (HEMT) power amplifier (PA). The AlGaN/GaN HEMT PA with gate periphery of 1 mm was built and tested at L-band. Large-signal measurements and comparisons of the PAE and output power were carried out at different DC bias conditions from 50% of saturated drain current (I/sub dss/) to 1% of Id., for the PA with and without output harmonic termination. For class-AB operation at 25% of I/sub dss/, an increase of about 10% in peak PAE and 1 dBm in output power were observed in saturated output power range. Improvements of up to 9% in PAE and 1.2 dBm in output power were achieved over the measured DC bias conditions provided the output harmonics are properly terminated. Effects of output harmonic termination on PAE and output power of AlGaN/GaN HEMT power amplifier Y Chung CY Hang S Cai Y Chen W Lee CP Wen KL Wang T Itoh doi:10.1109/LMWC.2002.805532 Microwave and Wireless Components Letters, IEEE, Vol. 12, No. 11. (2002), pp. 421-423. 2008-05-09T23:49:18-00:00 2002 Microwave and Wireless Components Letters, IEEE 12 11 421 423 amplifier power http://www.citeulike.org/user/dcastro/article/2776284 <i>Microwave Symposium Digest, 2001 IEEE MTT-S International, Vol. 2 (2001), pp. 1079-1082 vol.2.</i><br /><br />A high-efficiency class-AB push-pull power amplifier is designed utilizing a novel photonic band-gap (PBG) ground plane. This design allows simultaneous tuning of both the second and the third harmonics, thus resulting in a high efficiency power amplifier design. The measured PAE is 63.8% at an output power of 28.2 dBm. In addition, the measured IP3 is 45 dBm, about 17 dB above the P_1dB point High efficiency S-band class AB push-pull power amplifier with wideband harmonic suppression CY Hang Y Qian T Itoh doi:10.1109/MWSYM.2001.967079 Microwave Symposium Digest, 2001 IEEE MTT-S International, Vol. 2 (2001), pp. 1079-1082 vol.2. 2008-05-09T16:43:06-00:00 2001 Microwave Symposium Digest, 2001 IEEE MTT-S International 2 1079 1082 vol.2 amplifier s-band wideband http://www.citeulike.org/user/dcastro/article/2776235 <i>Microwave and Guided Wave Letters, IEEE [see also IEEE Microwave and Wireless Components Letters], Vol. 8, No. 1. (1998), pp. 13-14.</i><br /><br />Two class AB GaAs field-effect transistor (FET) power amplifiers have been designed and fabricated in the 4.4-4.8 GHz range. In the first case, a dielectric PBG line was incorporated in the design to tune the second harmonic. In the second case, a 50-Ω line is used with no harmonic tuning. The PBG structure allows broad-band harmonic tuning and is inexpensive to fabricate. A 5% improvement in power-added efficiency was achieved at the design frequency of 4.5 GHz, in both simulation and measurement Broad-band power amplifier using dielectric photonic bandgap structure V Radisic Y Qian T Itoh doi:10.1109/75.650973 Microwave and Guided Wave Letters, IEEE [see also IEEE Microwave and Wireless Components Letters], Vol. 8, No. 1. (1998), pp. 13-14. 2008-05-09T16:12:55-00:00 1998 Microwave and Guided Wave Letters, IEEE [see also IEEE Microwave and Wireless Components Letters] 8 1 13 14 amplifier broadband pbg power http://www.citeulike.org/user/dcastro/article/2776231 <i>Microwave Magazine, IEEE, Vol. 7, No. 1. (2006), pp. 40-48.</i><br /><br />This article provides a tutorial and review of recent developments in high-efficiency class F RF/ microwave PAs. The principles of class-F RF PAs are explained first. Recent progress in their theory and in design techniques is then presented. Different approaches of class-F PA designs are explained, and some examples of practical designs are illustrated. Finally, an attempt is made to discuss the future developments of class-F RF/microwave PAs. High efficiency class-F RF/microwave power amplifiers S Gao doi:10.1109/MMW.2006.1614233 Microwave Magazine, IEEE, Vol. 7, No. 1. (2006), pp. 40-48. 2008-05-09T16:11:33-00:00 2006 Microwave Magazine, IEEE 7 1 40 48 amplifier power http://www.citeulike.org/user/dcastro/article/2776230 <i>Microwave Theory and Techniques, IEEE Transactions on, Vol. 51, No. 2. (2003), pp. 653-659.</i><br /><br />A high-efficiency and compact AlGaN/GaN heterojunction field-effect transistor (HFET) power amplifier integrated with a microstrip antenna at 7.25 GHz is presented for RF front-end circuit applications. A microstrip circular sector antenna is employed as both a radiator and frequency-dependent output load. Higher order harmonics from the HFET in nonlinear operation are reactively terminated because of the harmonic termination characteristic of the antenna. Based on the optimum load impedance measured by a load-pull measurement setup, the AlGaN/GaN HFET power amplifier has been designed and fabricated at 7.25 GHz using the active integrated antenna concept. In this design approach, the measured antenna impedance is directly transformed to the optimum load impedance for maximum efficiency. The power amplifier with 1-mm gate periphery shows 42% peak power-added efficiency and 30.3-dBm saturated output power with a linear gain of 8 dB, which is in reasonably good agreement with measured discrete HFET load-pull data. Due to the antenna's characteristics, better than 30-dB harmonic suppression has been achieved at both the second and third harmonic frequencies in both the E- and H-planes. To the authors' best knowledge, this is the first demonstration of a high-frequency AlGaN/GaN HFET power amplifier integrated with an antenna. AlGaN/GaN HFET power amplifier integrated with microstrip antenna for RF front-end applications Younkyu Chung CY Hang S Cai Yongxi Qian CP Wen KL Wang T Itoh doi:10.1109/TMTT.2002.807685 Microwave Theory and Techniques, IEEE Transactions on, Vol. 51, No. 2. (2003), pp. 653-659. 2008-05-09T16:11:09-00:00 2003 Microwave Theory and Techniques, IEEE Transactions on 51 2 653 659 active amplifier antenna integrated power http://www.citeulike.org/user/dcastro/article/2776127 <i>Electronics Letters, Vol. 29, No. 18. (1993), pp. 1633-1635.</i><br /><br />A systematic method for optimising the performance of feedforward linearised microwave power amplifiers has been developed. Simulated and practical feedforward systems optimised with this method achieve significant improvement in third order intermodulation product level and compression point Optimisation method for feedforward linearisation of power amplifiers K Konstantinou P Gardner DK Paul Electronics Letters, Vol. 29, No. 18. (1993), pp. 1633-1635. 2008-05-09T15:21:03-00:00 1993 Electronics Letters 29 18 1633 1635 amplifier power http://www.citeulike.org/user/dcastro/article/2776114 <i>Millimetre Wave Transistors and Circuits, IEE Colloquium on (1991), pp. 10/1-10/4.</i><br /><br />Negative resistance, reflection mode amplification using GaAs FETs or HEMTs offers the possibility of realising the low noise performance associated with such devices whilst achieving a higher gain per stage than conventional transmission mode amplifiers. This possibility is of particular interest in the MM-wave region, where the gain per stage of conventional FET and HEMT amplifiers, when tuned for optimum noise measure, is low. An additional potential benefit, of particular interest for radar LNA applications, is the probable existence of a low loss bypass path through a reflection amplifier after failure of the active device. In this paper, the circuit conditions for optimum noise measure in negative resistance transistor amplifiers are determined, and several examples are given. Design details and measured results are given for an example in X-band. The suitability of the technique for MM-wave frequencies is assessed as far as possible using published S-parameter and noise data for a HEMT device, and a theoretical circuit design is presented Negative resistance low noise, reflection mode transistor amplifiers for microwave and millimetre wave applications DK Paul P Gardner Millimetre Wave Transistors and Circuits, IEE Colloquium on (1991), pp. 10/1-10/4. 2008-05-09T15:18:10-00:00 1991 Millimetre Wave Transistors and Circuits, IEE Colloquium on 10/1 10/4 amplifier low microwave noise http://www.citeulike.org/user/dcastro/article/2776113 <i>Microwave Theory and Techniques, IEEE Transactions on, Vol. 39, No. 11. (1991), pp. 1869-1875.</i><br /><br />The authors consider the use of microwave transistors in the negative resistance reflection mode and present the conditions for optimum noise performance. Possible advantages include the possibility of higher gain in the millimeter-wave region, which can be achieved by absorbing the parasitic common lead inductance into the feedback circuit designed to generate the negative resistance, and the existence of a failsafe mode of operation, in that the failure of the active device or its power supply is likely to lead a low return loss, resulting in a small insertion loss through the amplifiers, which may permit continued, although degraded, system operation. The latter potential advantage has proved to be of interest to radar system designers Aspects of the design of low noise, negative resistance, reflection mode transistor amplifiers P Gardner DK Paul doi:10.1109/22.97488 Microwave Theory and Techniques, IEEE Transactions on, Vol. 39, No. 11. (1991), pp. 1869-1875. 2008-05-09T15:18:10-00:00 1991 Microwave Theory and Techniques, IEEE Transactions on 39 11 1869 1875 amplifier low noise transistor http://www.citeulike.org/user/dcastro/article/2776112 <i>Circuits Theory, IEEE Transactions on [legacy, pre - 1988], Vol. 10, No. 1. (1963), pp. 45-48.</i><br /><br />Noise figure of transistor amplifiers is commonly optimized by transforming of source impedance. Where transformers are not feasible, this method is inapplicable. This paper shows that noise figure can also be optimized by proper adjustment of emitter current with the source impedance remaining fixed. Moreover, for a rather wide range of source impedances, transformation affords very little noise improvement once the current has been optimized. Circuit design equations and curves are presented. Optimum Noise Figure of Transistor Amplifiers F Gardner Circuits Theory, IEEE Transactions on [legacy, pre - 1988], Vol. 10, No. 1. (1963), pp. 45-48. 2008-05-09T15:18:08-00:00 1963 Circuits Theory, IEEE Transactions on [legacy, pre - 1988] 10 1 45 48 amplifier noise transistor http://www.citeulike.org/user/dcastro/article/2776111 <i>Electronics Letters, Vol. 29, No. 16. (1993), pp. 1408-1409.</i><br /><br />The limited gain available from GaAs FETs and HEMTs at millimetric frequencies can be overcome by using the devices in a negative resistance amplifier configuration. The advantage of the solid-state negative resistance amplifier over the transmission amplifier is that the gain available is not limited by the active device used. It has been shown that, over a narrow bandwidth, significantly higher gain can be obtained from a negative resistance amplifier, when compared to a transmission amplifier using the same device, while maintaining the same overall noise performance. This has been demonstrated experimentally using a 0.25 μm HEMT device High gain millimetric negative resistance low noise amplifiers MT Hickson P Gardner DK Paul Electronics Letters, Vol. 29, No. 16. (1993), pp. 1408-1409. 2008-05-09T15:18:07-00:00 1993 Electronics Letters 29 16 1408 1409 amplifier gain high low noise http://www.citeulike.org/user/dcastro/article/2776109 <i>Antennas and Propagation Society International Symposium, 2002. IEEE, Vol. 2 (2002), pp. 508-511 vol.2.</i><br /><br />Both theoretical and experimental results of a novel integrated antenna for LINC power amplifiers are presented. The integrated antenna can also serve as a power combiner, ensuring maximum power efficiency. This will be a significant advance on current LINC and CALLIUM systems, where the circuit level power combiner losses degrade overall efficiency. The concept is explained and one example antenna at 1.8 GHz is designed, fabricated and measured. The measured results show that the antenna achieves good impedance matching characteristics under both the common-mode and the differential-mode excitations. Radiation patterns are also presented. Novel integrated antenna for LINC power amplifiers SC Gao P Gardner doi:10.1109/APS.2002.1016133 Antennas and Propagation Society International Symposium, 2002. IEEE, Vol. 2 (2002), pp. 508-511 vol.2. 2008-05-09T15:18:04-00:00 2002 Antennas and Propagation Society International Symposium, 2002. IEEE 2 508 511 vol.2 active amplifier antenna integrated power http://www.citeulike.org/user/dcastro/article/2774765 <i>Microwave Symposium Digest, 1995., IEEE MTT-S International (1995), pp. 1099-1102 vol.3.</i><br /><br />This paper presents an 18 GHz circularly polarised multilayer active antenna subarray using MMIC amplifiers. With the advantage of a multilayer structure, the radiation patterns from the antenna side are not affected by the radiation from the circuit side. An extra gain of 15.46 dB has been measured in comparison to the passive array. This type of array can be the ideal building block for large microstrip phased array systems An 18 GHz circularly polarised multilayer active microstrip antenna subarray using MMIC amplifiers D Sanchez-Hernandez M Gillick I Robertson doi:10.1109/MWSYM.1995.406163 Microwave Symposium Digest, 1995., IEEE MTT-S International (1995), pp. 1099-1102 vol.3. 2008-05-09T08:35:42-00:00 1995 Microwave Symposium Digest, 1995., IEEE MTT-S International 1099 1102 vol.3 active amplifier antenna circular microstrip multilayer polarisation http://www.citeulike.org/user/dcastro/article/2774758 <i>Military Communications Conference, 1998. MILCOM 98. Proceedings., IEEE, Vol. 3 (1998), pp. 699-703 vol.3.</i><br /><br />This paper reports two techniques for optimizing harmonic termination in power amplifiers. In the first technique, the active antenna approach, the antenna element acts as radiator and as part of the output tuning circuit. The second method, based on photonic band-gap (PBG) structure, incorporates a periodic harmonic tuning structure for microstrip lines. In this structure, a periodic 2-D pattern is etched in the microstrip ground plane. A wide stopband suitable for broadband harmonic tuning, has been demonstrated experimentally. These methods yield high efficiency power amplifiers, and reduce unwanted radiation from the antenna at harmonics. Two power amplifier examples are presented Active antenna approach to high efficiency power amplifiers with EMI reduction V Radisic Yongxi Qian T Itoh doi:10.1109/MILCOM.1998.726914 Military Communications Conference, 1998. MILCOM 98. Proceedings., IEEE, Vol. 3 (1998), pp. 699-703 vol.3. 2008-05-09T08:35:16-00:00 1998 Military Communications Conference, 1998. MILCOM 98. Proceedings., IEEE 3 699 703 vol.3 active amplifier antenna efficiency high power http://www.citeulike.org/user/dcastro/article/2774757 <i>Microwave Theory and Techniques, IEEE Transactions on, Vol. 50, No. 1. (2002), pp. 288-301.</i><br /><br />The concept of concurrent multiband low-noise-amplifiers (LNAs) is introduced. A systematic way to design concurrent multiband integrated LNAs in general is developed. Applications of concurrent multiband LNAs in concurrent multiband receivers together with receiver architecture are discussed. Experimental results of a dual-band LNA implemented in a 0.35-μm CMOS technology as a demonstration of the concept and theory is presented Concurrent multiband low-noise amplifiers-theory, design, and applications H Hashemi A Hajimiri doi:10.1109/22.981282 Microwave Theory and Techniques, IEEE Transactions on, Vol. 50, No. 1. (2002), pp. 288-301. 2008-05-09T08:35:16-00:00 2002 Microwave Theory and Techniques, IEEE Transactions on 50 1 288 301 amplifier application design low multiband noise theory http://www.citeulike.org/user/dcastro/article/2774607 <i>Microwave Symposium Digest, 1998 IEEE MTT-S International, Vol. 2 (1998), pp. 455-458 vol.2.</i><br /><br />This paper describes a high efficiency amplifier that uses the load presented by a patch antenna to work in class “E”. The resulting set is a high efficiency transmitting active antenna. The dimensions, shape and location of the feeding point in the antenna are selected to obtain an input impedance to force the transistor to work in class “E” at 885 MHz with very high collector efficiency: ηc=90%@Vcc=12.5, Pout=1.5 W High efficiency mode “E” amplifier powers high efficiency active transmitting patch antenna Ortega Asensio Gonzalez Jimenez Martin doi:10.1109/MWSYM.1998.705031 Microwave Symposium Digest, 1998 IEEE MTT-S International, Vol. 2 (1998), pp. 455-458 vol.2. 2008-05-09T07:26:00-00:00 1998 Microwave Symposium Digest, 1998 IEEE MTT-S International 2 455 458 vol.2 active amplifier antenna efficiency high patch transmitter http://www.citeulike.org/user/dcastro/article/2774599 <i>Microwave Symposium Digest, 1998 IEEE MTT-S International, Vol. 2 (1998), pp. 997-1000 vol.2.</i><br /><br />This paper presents a novel idea that the power is fed from the patch antenna coupler to form a five-element Chebyshev active antenna FET amplifying linear array. An equivalent lumped element circuit was developed to model the mutual coupling having good agreement with experiments. The power level coupled to the transmission line can be controlled by adjusting the length and the gap of the transmission line. The active patch-fed antenna coupler array has the advantages of a single input port, no power divider required, good and controllable radiation patterns, ease of bias, and compactness Novel active antenna amplifying arrays Yao-Chou Yang Shyh-Jong Chung Kai Chang doi:10.1109/MWSYM.1998.705160 Microwave Symposium Digest, 1998 IEEE MTT-S International, Vol. 2 (1998), pp. 997-1000 vol.2. 2008-05-09T07:24:23-00:00 1998 Microwave Symposium Digest, 1998 IEEE MTT-S International 2 997 1000 vol.2 active amplifier antenna array http://www.citeulike.org/user/dcastro/article/2774493 <i>Solid-State Circuits, IEEE Journal of, Vol. 42, No. 11. (2007), pp. 2492-2502.</i><br /><br />This paper presents a wideband low-noise amplifier (LNA) designed to be used as the first stage of the receiver in the Square Kilometer Array radio telescope. The LNA design procedure and its layout features are discussed. The noise figure optimization procedure determines the signal-source resistance that results in reduced noise figure. When used in the radio telescope, the required signal-source resistance will be presented by the telescope custom-made antenna elements. The LNA, designed in 90 nm bulk CMOS, achieves sub-0.2 dB noise figure from 800 MHz to 1400 MHz, return loss of more than 11 dB, gain of more than 17 dB driven into a 50 load, output 1 dB compression point of 2 dBm, output IP3 of 12 dBm, and output IP2 of 22 dBm while consuming 43 mA from a 1 V supply. In the LNA implementation presented in this paper the load choke inductor and the source inductor are integrated whereas the gate-, bias-, and the choke-inductor between two transistors of the cascode are external. The noise figure of the presented LNA is to our knowledge the lowest noise figure achieved by a power matched wideband CMOS LNA at room temperature. Sub-0.2 dB Noise Figure Wideband Room-Temperature CMOS LNA With Non-50 Ω Signal-Source Impedance L Belostotski JW Haslett doi:10.1109/JSSC.2007.907172 Solid-State Circuits, IEEE Journal of, Vol. 42, No. 11. (2007), pp. 2492-2502. 2008-05-09T06:38:07-00:00 2007 Solid-State Circuits, IEEE Journal of 42 11 2492 2502 amplifier low noise wideband http://www.citeulike.org/user/dcastro/article/2762239 <i>Circuits, Devices and Systems, IEE Proceedings G, Vol. 136, No. 6. (1989), pp. 358-360.</i><br /><br />A novel method of determining the source and drain series parasitic resistances of the MESFET is presented. This method is particularly suited to power devices since it eliminates the necessity to operate the Schottky gate with high forward bias. In addition, the values of parasitic resistances extracted from low-frequency measurements are confirmed at microwave frequencies.<<ETX>> Method for determination of parasitic resistances in microwave power MESFETs KW Eccleston Circuits, Devices and Systems, IEE Proceedings G, Vol. 136, No. 6. (1989), pp. 358-360. 2008-05-06T18:33:16-00:00 1989 Circuits, Devices and Systems, IEE Proceedings G 136 6 358 360 amplifier fet microwave power http://www.citeulike.org/user/dcastro/article/2762236 <i>Microwave Conference, 1999 Asia Pacific, Vol. 3 (1999), pp. 638-641 vol.3.</i><br /><br />The dual-fed distributed amplifier is a variation of the conventional single-fed distributed amplifier. Namely, the input signal is fed to both ends of the input line and the power appearing at the ends of the output line is combined. This approach has the advantages of utilising power in both the forward and backward travelling waves on the output line, and the drain output power can be equalised among the FETs. In this paper, the operational behaviour of the dual-fed distributed power amplifier is investigated and the optimum operating conditions are identified. It has been shown that uniform power distribution can be achieved when the spacing between each FET is of the order of the guide wavelength and is dependent on the phase difference of the two input signals Analysis of the dual-fed distributed power amplifier KW Eccleston LT Ong PS Kooi BL Ooi doi:10.1109/APMC.1999.833672 Microwave Conference, 1999 Asia Pacific, Vol. 3 (1999), pp. 638-641 vol.3. 2008-05-06T18:33:09-00:00 1999 Microwave Conference, 1999 Asia Pacific 3 638 641 vol.3 amplifier distributed power http://www.citeulike.org/user/dcastro/article/2762235 <i>Microwave and Millimeter Wave Technology, 2002. Proceedings. ICMMT 2002. 2002 3rd International Conference on (2002), pp. 1142-1145.</i><br /><br />RF sub-systems in multimode/multiband wireless communication systems need to operate on different bands that are typically narrow but sparsely separated. We show that a single-ended dual-fed distributed amplifier can operate efficiently over several sparsely separated bands. This approach therefore alleviates the need for separate amplifiers for each band. Multiband power amplifier for multiband wireless applications KW Eccleston Microwave and Millimeter Wave Technology, 2002. Proceedings. ICMMT 2002. 2002 3rd International Conference on (2002), pp. 1142-1145. 2008-05-06T18:33:07-00:00 2002 Microwave and Millimeter Wave Technology, 2002. Proceedings. ICMMT 2002. 2002 3rd International Conference on 1142 1145 amplifier multiband power http://www.citeulike.org/user/dcastro/article/2762234 <i>Microwave and Millimeter Wave Technology, 2002. Proceedings. ICMMT 2002. 2002 3rd International Conference on (2002), pp. 919-922.</i><br /><br />The distributed amplifier approach allows the output powers of several FETs to be combined without the need for multi-way power combiners. In this paper we demonstrate that a balanced amplifier employing two single-ended dual-fed distributed amplifiers can operate effectively under class-B operation. Class-B operation and dual-feeding allow distributed amplification with significantly improved efficiencies compared to conventional distributed power amplifiers. The FETs are spaced 180 degrees to allow all FETs operate into identical optimum loadlines. The configuration uses all FET output power and has good port match. Class-B balanced single-ended dual-fed distributed power amplifier O Kyaw KW Eccleston Microwave and Millimeter Wave Technology, 2002. Proceedings. ICMMT 2002. 2002 3rd International Conference on (2002), pp. 919-922. 2008-05-06T18:33:06-00:00 2002 Microwave and Millimeter Wave Technology, 2002. Proceedings. ICMMT 2002. 2002 3rd International Conference on 919 922 amplifier distributed power http://www.citeulike.org/user/dcastro/article/2762233 <i>Microwave Conference, 2000 Asia-Pacific (2000), pp. 205-208.</i><br /><br />The dual-fed distributed amplifier is a variation of the conventional single-fed distributed amplifier whereby the input signal is fed to both ends of the input line using a hybrid, and signals appearing at both ends of the output line are combined using another hybrid. Such a configuration allows utilisation of output power in the backward as well as forward waves. Much of the previous work in the literature only considered small-signal analysis and small electrical spacing between FETs, and did not lend insight into the operational behaviour. This paper therefore considers the development of a design method for the dual-fed distributed power amplifier with large electrical spacing. The simulations demonstrate optimum loadlines are achieved for all FETs and that all FET output power is utilised Design considerations for the dual-fed distributed power amplifier KW Eccleston doi:10.1109/APMC.2000.925763 Microwave Conference, 2000 Asia-Pacific (2000), pp. 205-208. 2008-05-06T18:33:03-00:00 2000 Microwave Conference, 2000 Asia-Pacific 205 208 amplifier design distributed power http://www.citeulike.org/user/dcastro/article/2762228 <i>Microwave Theory and Techniques, IEEE Transactions on, Vol. 53, No. 3. (2005), pp. 825-831.</i><br /><br />The dual-fed distributed amplifier (DFDA) allows efficient combining of field-effect transistors (FETs) at the device level without using n-way power combiners. However, the FETs must be spaced 180/spl deg/, resulting in physically large circuits. In this paper, meandered artificial transmission lines (TLs) comprised of microstrip lines periodically loaded with short open-circuit stubs can be used in place of TLs to reduce the size. The approach incorporates FET input and output capacitances with the artificial TLs, thereby eliminating their detrimental effects on bandwidth and performance. Both simulation and experimental results of a class-A three-FET single-ended DFDA designed to operate at 1.8 GHz demonstrate the feasibility of this approach and the validity of the design method. The size reduction is approximately one-third compared to realization using microstrip lines only, and the maximum efficiency is greater than 35% over a bandwidth of 15%. Compact dual-fed distributed power amplifier KW Eccleston doi:10.1109/TMTT.2004.842508 Microwave Theory and Techniques, IEEE Transactions on, Vol. 53, No. 3. (2005), pp. 825-831. 2008-05-06T18:31:05-00:00 2005 Microwave Theory and Techniques, IEEE Transactions on 53 3 825 831 amplifier distributed power http://www.citeulike.org/user/dcastro/article/2762227 <i>Microwave Conference, 2001. APMC 2001. 2001 Asia-Pacific, Vol. 3 (2001), pp. 1187-1190 vol.3.</i><br /><br />In this paper we demonstrate a design method for the balanced amplifier employing two single-ended dual-fed distributed power amplifiers. The method ensures that all FET output power is utilised, all FETs have equal output power at the centre frequency and operate into identical, optimum loadlines. The amplifier has improved efficiency compared to the conventional distributed amplifier and has improved input and output match compared to the dual-fed distributed amplifier Design and performance of a balanced single-ended dual-fed distributed power amplifier KW Eccleston doi:10.1109/APMC.2001.985345 Microwave Conference, 2001. APMC 2001. 2001 Asia-Pacific, Vol. 3 (2001), pp. 1187-1190 vol.3. 2008-05-06T18:31:02-00:00 2001 Microwave Conference, 2001. APMC 2001. 2001 Asia-Pacific 3 1187 1190 vol.3 amplifier power http://www.citeulike.org/user/dcastro/article/2762207 <i>Modelling, Design and Application of MMIC's, IEE Colloquium on (1994), pp. 6/1-6/6.</i><br /><br />Measured and modelled six port S-parameters for three wide FETs are presented from O.1-20 GHz. Directional coupling is observed between source and drain lines, the directivity of which is tunable by DC gate bias. Tunable directivities of greater than 20 dB from 8 to 12 GHz are predicted for the de-embedded device A comparison of three wide FETs configured as controllable couplers MJ Cryan PR Shepherd SR Pennock Modelling, Design and Application of MMIC's, IEE Colloquium on (1994), pp. 6/1-6/6. 2008-05-06T18:26:34-00:00 1994 Modelling, Design and Application of MMIC's, IEE Colloquium on 6/1 6/6 amplifier coupler fet http://www.citeulike.org/user/dcastro/article/2762158 <i>Microwave Symposium Digest, 2002 IEEE MTT-S International, Vol. 1 (2002), pp. 433-436.</i><br /><br />In this paper, effects of output harmonic terminations on PAE and output power of AlGaN/GaN HEMT power amplifier are investigated. Using a traditional method of harmonic termination, we observe a substantial increase in PAE and output power. Further, we demonstrate the high efficiency AlGaN/GaN HEMT power amplifier with harmonic termination characteristics by using the active integrated antenna approach. For the microstrip-based AlGaN/GaN HEMT power amplifier, large signal measurements and comparisons of PAE and output power were done in class-AB operation with and without output harmonic terminations. For the antenna integrated power amplifier using an AlGaN/GaN HEMT with 1 mm gate periphery, output power of 30 dBm and peak PAE of 55 % with a power gain of 14 dB were achieved at a drain voltage of 18 V and a gate voltage of -2.8 V Output harmonic termination techniques for AlGaN/GaN HEMT power amplifiers using active integrated antenna approach Younkyu Chung CY Hang Shujun Cai Yongxi Qian CP Wen KL Wang T Toh doi:10.1109/MWSYM.2002.1011648 Microwave Symposium Digest, 2002 IEEE MTT-S International, Vol. 1 (2002), pp. 433-436. 2008-05-06T17:44:54-00:00 2002 Microwave Symposium Digest, 2002 IEEE MTT-S International 1 433 436 active amplifier antenna integrated power http://www.citeulike.org/user/dcastro/article/2762157 <i>Microwave Symposium Digest, 2002 IEEE MTT-S International, Vol. 2 (2002), pp. 913-916.</i><br /><br />This paper presents a new power combining scheme, which has either one or four amplifiers on depending upon the levels of input signal. This approach realized by utilizing a unique combiner that is lossless and has constant gain under both scenarios. As a result, for the system where variable output power is required, this combining scheme can be used in an amplifier design with optimum efficiency. Measurement data show 15% power efficiency for the four-amplifier scenario and 28% for the single amplifier scenario at 13dBm input power. We also investigate the possibility of using this combiner in an envelope tracking amplifier A new amplifier power combining scheme with optimum efficiency under variable outputs CY Hang Y Wang T Itoh doi:10.1109/MWSYM.2002.1011778 Microwave Symposium Digest, 2002 IEEE MTT-S International, Vol. 2 (2002), pp. 913-916. 2008-05-06T17:44:51-00:00 2002 Microwave Symposium Digest, 2002 IEEE MTT-S International 2 913 916 amplifier efficiency power http://www.citeulike.org/user/dcastro/article/2762156 <i></i><br /><br />In this paper, a high efficiency class-AB pushpull power amplifier is designed utilizing a novel photonic band-gap (PBG) ground plane. This design allows simultaneous tuning of both second and the third harmonics, thus, results in a high efficient power amplifier design. The measured PAE is 63.8% at an output power of 28.2dBm. In addition, the measured IP3 is 45 dBm, about 17 dB above the P 1dB point. . High Efficiency S-band Class AB Push-Pull Power Amplifier with Wide Band Harmonic Suppression Cynthia Hang Yongxi Qian Tatsuo Itoh 2008-05-06T17:44:50-00:00 amplifier power http://www.citeulike.org/user/dcastro/article/2762155 <i>Microwave Symposium Digest, 1998 IEEE MTT-S International, Vol. 3 (1998), pp. 1895-1898 vol.3.</i><br /><br />A high efficiency class-AB GaAs FET power amplifier integrated with a slot antenna has been designed and fabricated. Broadband second harmonic tuning was achieved using a microstrip line with a periodically etched ground plane. Power-added efficiency greater than 50% was achieved in the 3.7-4.0 GHz bandwidth Broadband power amplifier integrated with slot antenna and novel harmonic tuning structure V Radisic Yongxi Qian T Itoh doi:10.1109/MWSYM.1998.700863 Microwave Symposium Digest, 1998 IEEE MTT-S International, Vol. 3 (1998), pp. 1895-1898 vol.3. 2008-05-06T17:44:46-00:00 1998 Microwave Symposium Digest, 1998 IEEE MTT-S International 3 1895 1898 vol.3 active amplifier antenna integrated power http://www.citeulike.org/user/dcastro/article/2762149 <i>Microwave and Guided Wave Letters, IEEE [see also IEEE Microwave and Wireless Components Letters], Vol. 7, No. 2. (1997), pp. 39-41.</i><br /><br />Two class B GaAs field-effect transistor (FET) power amplifiers integrated with patch antennas have been designed and fabricated at 2.48 GHz. Both amplifiers are integrated with patch antennas, which serve as load and radiator. In one case, a standard patch design was used with random harmonic termination. In another case, a modified patch design was used, which allows the tuning of the second harmonic. In this case the antenna has an additional function of a filter. An increase of 7% in the power-added efficiency (PAE) and 0.5 dB in the output power was achieved through the second harmonic tuning High-efficiency power amplifier integrated with antenna V Radisic Siou Chew Yongxi Qian T Itoh doi:10.1109/75.553052 Microwave and Guided Wave Letters, IEEE [see also IEEE Microwave and Wireless Components Letters], Vol. 7, No. 2. (1997), pp. 39-41. 2008-05-06T17:42:53-00:00 1997 Microwave and Guided Wave Letters, IEEE [see also IEEE Microwave and Wireless Components Letters] 7 2 39 41 active amplifier antenna integrated http://www.citeulike.org/user/dcastro/article/2762148 <i>Microwave Symposium Digest, 1998 IEEE MTT-S International, Vol. 2 (1998), pp. 589-592 vol.2.</i><br /><br />This paper presents a technique for raising power efficiency in portable wireless transmitters by integrating a variable voltage output DC-DC converter together with a MESFET RF power amplifier. Significant increases in power efficiency are obtainable over a large range of output power levels. The system includes an envelope detector, a closed feedback loop, and a pulse width modulator operating at 10 MHz. A 300 mW transmitter is shown for which battery life can be extended by over 1.4 times Microwave power amplifier efficiency improvement with a 10 MHz HBT DC-DC converter G Hanington PF Chen V Radisic T Itoh PM Asbeck doi:10.1109/MWSYM.1998.705062 Microwave Symposium Digest, 1998 IEEE MTT-S International, Vol. 2 (1998), pp. 589-592 vol.2. 2008-05-06T17:42:50-00:00 1998 Microwave Symposium Digest, 1998 IEEE MTT-S International 2 589 592 vol.2 amplifier power