Thu, 07 Aug 2008 21:21:11 BST CiteULike: Author Asbeck http://www.citeulike.org/author/Asbeck CiteULike.org en-gb Copyright © 2004-2008 citeulike.org 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/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/2762226 <i>Microwave Symposium Digest, 1998 IEEE MTT-S International, Vol. 1 (1998), pp. 327-330 vol.1.</i><br /><br />This paper presents several power amplifier approaches that promise to significantly improve efficiency, while meeting the linearity requirements of advanced, spectrally efficient wireless systems. The approaches include: a) use of active integrated antenna structures that provide harmonic terminations for high efficiency Class F amplifiers; b) integrated dc-dc converters for power conditioning and envelope restoration; c) switching mode amplifiers based on bipolar transistors with controlled saturation; and d) the use of band-pass delta-sigma modulators to tailor input signals Device and circuit approaches for improved linearity and efficiency in microwave transmitters PM Asbeck T Itoh Y Qian MF Chang L Milstein G Hanington PF Chen V Schultz DW Lee DW Lee J Arun A10 doi:10.1109/MWSYM.1998.689385 Microwave Symposium Digest, 1998 IEEE MTT-S International, Vol. 1 (1998), pp. 327-330 vol.1. 2008-05-06T18:30:58-00:00 1998 Microwave Symposium Digest, 1998 IEEE MTT-S International 1 327 330 vol.1 efficiency microwave transmitter 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 http://www.citeulike.org/user/hoverste/article/2755116 <i>Microwave Symposium Digest, 2005 IEEE MTT-S International (2005), 4 pp..</i><br /><br />This paper introduces the envelope model reference adaptive control construct to digital predistortion of RF power amplifiers. It is used to formulate a block level predistortion algorithm that compensates for the both memoryless compression characteristics and deterministic memory effects. An iterative technique of successive approximations is used to obtain the memory effect inverse function. The algorithm is applied to two amplifiers and convergence is demonstrated. Qualitative results (instantaneous input/output plots) and quantitative results (the sequence and ensemble RMS error over the iteration sequence) are presented. Memory effect evaluation and predistortion of power amplifiers P Draxler J Deng D Kimball I Langmore PM Asbeck doi:10.1109/MWSYM.2005.1516993 Microwave Symposium Digest, 2005 IEEE MTT-S International (2005), 4 pp.. 2008-05-05T04:29:46-00:00 2005 Microwave Symposium Digest, 2005 IEEE MTT-S International 4 pp. dpd memory http://www.citeulike.org/user/hoverste/article/2755114 <i>Compound Semiconductor Integrated Circuit Symposium, 2005. CSIC '05. IEEE (2005), 4 pp..</i><br /><br />A high performance GaN HFET WCDMA basestation power amplifier is presented, which uses an envelope tracking bias system to achieve high linearity and efficiency. The measured overall power-added efficiency (PAE) reached 50.7%, with a normalized power RMS error of 0.7% and ACLR of -52dBc at an offset frequency of 5MHz, at an average output power of 37.2W and gain of 10.0dB for a single carrier WCDMA signal. To the authors' knowledge, this corresponds to the best efficiency reported for a single stage base station power amplifier. Digital predistortion (DPD) was used at two levels: memoryless DPD to compensate for the expected gain variation of the amplifier over the bias envelope trajectory, and deterministic memory mitigation, to further improve the linearity. The signal envelope had a peak-to-average power ratio of 7.67dB. 50% PAE WCDMA basestation amplifier implemented with GaN HFETs D Kimball P Draxler J Jeong C Hsia S Lanfranco W Nagy K Linthicum L Larson P Asbeck P Asbeck doi:10.1109/CSICS.2005.1531768 Compound Semiconductor Integrated Circuit Symposium, 2005. CSIC '05. IEEE (2005), 4 pp.. 2008-05-05T04:27:51-00:00 2005 Compound Semiconductor Integrated Circuit Symposium, 2005. CSIC '05. IEEE 4 pp. basestation dpd envelope et gan memory tracking wcdma http://www.citeulike.org/user/hoverste/article/2755060 <i>Microwave Theory and Techniques, IEEE Transactions on, Vol. 54, No. 12. (2006), pp. 4086-4099.</i><br /><br />A comparison of envelope elimination and restoration (EER) and envelope tracking (ET) is discussed and a "hybrid" wideband EER power amplifier (PA) for the WLAN 802.11g system is proposed. A 60% efficiency (the output envelope signal power/input dc power) DC-20-MHz wideband envelope amplifier is designed for wideband EER and wideband ET (WBET) applications. A design method is developed to optimize the efficiency of the envelope amplifier for a given peak-to-average ratio and average slew rate of the envelope signal. An experimental "hybrid" Class-E EER system shows an overall efficiency (modulated RF output power/envelope amplifier dc input power) of 36% and power-added efficiency (the modulated RF output power/envelope amplifier dc input power plus RF input power) of 28% for a WLAN 802.11g signal at 19-dBm (80 mW) output power at 2.4 GHz. Digital predistortion, time alignment, and memory effect mitigation are implemented. The measured 3% error vector magnitude exceeds the 802.11g specification for 5% for a 54-Mb/s modulation signal An Improved Power-Added Efficiency 19-dBm Hybrid Envelope Elimination and Restoration Power Amplifier for 802.11g WLAN Applications F Wang DF Kimball JD Popp AH Yang DY Lie PM Asbeck LE Larson doi:10.1109/TMTT.2006.885575 Microwave Theory and Techniques, IEEE Transactions on, Vol. 54, No. 12. (2006), pp. 4086-4099. 2008-05-05T03:56:53-00:00 2006 Microwave Theory and Techniques, IEEE Transactions on 54 12 4086 4099 alignment amplifier class-e dpd eer envelope memory time tracking wideband http://www.citeulike.org/user/hoverste/article/2754999 <i>Microwave Symposium Digest, 2006. IEEE MTT-S International (2006), pp. 1534-1537.</i><br /><br />A high performance W-CDMA base station power amplifier is presented, which uses an envelope tracking bias system along with an advanced 0.4mum gate length LDMOS transistor, to achieve high efficiency. High linearity is also achieved by employing digital predistortion. For a target WCDMA envelope with a peak-to-average power ratio of 7.6 dB, the measured overall power-added efficiency (PAE) is as high as 40.4 %. Within this system, the RF power amplifier has an average drain efficiency of approximately 64%, and the envelope amplifier has about 60% efficiency. After the memoryless digital predistortion the normalized power RMS error is 3.3%, at an average output power of 27 W and gain of 14.9 dB. After memory mitigation the normalized power RMS error drops to below 1.0%. The efficiency ranks among the highest reported for a single stage LDMOS W-CDMA base station amplifier High Efficiency Envelope Tracking LDMOS Power Amplifier for W-CDMA P Draxler S Lanfranco D Kimball C Hsia J Jeong J van de Sluis PM Asbeck doi:10.1109/MWSYM.2006.249605 Microwave Symposium Digest, 2006. IEEE MTT-S International (2006), pp. 1534-1537. 2008-05-05T03:19:30-00:00 2006 Microwave Symposium Digest, 2006. IEEE MTT-S International 1534 1537 asbeck dpd draxler envelope kimball ldmos tracking wcdma http://www.citeulike.org/user/hoverste/article/2754969 <i>Microwave Conference, 2006. APMC 2006. Asia-Pacific (2006), pp. 1048-1051.</i><br /><br />Future generations of wireless communications are expected to place increasing burdens on the efficiency and linearity of power amplifiers, due to the use of more complex multi-carrier waveforms and OFDM. This has implications for the design of transmitters in portable/mobile devices as well as base stations and access points. This paper will summarize the digital predistortion techniques that can be employed to improve the performance of wireless power amplifiers. Digital predistortion techniques for linearized power amplifiers L Larson D Kimball P Asbeck P Draxler Junxiong Deng Ming Li doi:10.1109/APMC.2006.4429590 Microwave Conference, 2006. APMC 2006. Asia-Pacific (2006), pp. 1048-1051. 2008-05-05T03:12:10-00:00 2006 Microwave Conference, 2006. APMC 2006. Asia-Pacific 1048 1051 asbeck dpd draxler kimball summary http://www.citeulike.org/user/hoverste/article/2754924 <i>Radio Frequency integrated Circuits (RFIC) Symposium, 2005. Digest of Papers. 2005 IEEE (2005), pp. 247-250.</i><br /><br />The paper demonstrates a two-stage 1.95 GHz WCDMA handset RFIC power amplifier (PA) implemented in 1.8 mm/sup 2/ in a 250 nm SiGe BiCMOS process. With an integrated dual dynamic bias control of the collector current and the collector voltage in the output stage, the average power efficiency of the two-stage PA is improved by over a factor of two. An off-chip memoryless digital predistortion is also adopted to improve the linearity of the power amplifier, satisfying the 3GPP WCDMA adjacent channel power ratio (ACPR) specifications with 26 dBm average channel output power and a peak power-added efficiency of 27%. A SiGe PA with dual dynamic bias control and memoryless digital predistortion for WCDMA handset applications Junxiong Deng P Gudem LE Larson D Kimball PM Asbeck doi:10.1109/RFIC.2005.1489774 Radio Frequency integrated Circuits (RFIC) Symposium, 2005. Digest of Papers. 2005 IEEE (2005), pp. 247-250. 2008-05-05T02:46:18-00:00 2005 Radio Frequency integrated Circuits (RFIC) Symposium, 2005. Digest of Papers. 2005 IEEE 247 250 asbeck dpd handset implementation kimball sige wcdma http://www.citeulike.org/user/hoverste/article/2754921 <i>Radio and Wireless Symposium, 2006 IEEE (2006), pp. 259-262.</i><br /><br />Digital predistortion linearization results are often degraded by nonideal factors in the transmitter chain. Among them, the gain ripple and phase delay of the analog reconstruction filter and the gain and phase imbalance of quadrature modulator are the major sources of linearizer performance degradation. The paper studies these effects and presents general guidelines for filter selection and imbalance compensation to maximize the predistortion performance. Nonideal effects of reconstruction filter and I/Q imbalance in digital predistortion MY Li JX Deng LE Larson PM Asbeck doi:10.1109/RWS.2006.1615144 Radio and Wireless Symposium, 2006 IEEE (2006), pp. 259-262. 2008-05-05T02:44:14-00:00 2006 Radio and Wireless Symposium, 2006 IEEE 259 262 asbeck dpd filter imbalance iq reconstruction transmitter http://www.citeulike.org/user/hoverste/article/2754897 <i>Solid-State Circuits, IEEE Journal of, Vol. 41, No. 5. (2006), pp. 1210-1221.</i><br /><br />This paper demonstrates a two-stage 1.95-GHz WCDMA handset RFIC power amplifier (PA) implemented in a 0.25-/spl mu/m SiGe BiCMOS process. With an integrated dual dynamic bias control of the collector current and collector voltage, the average power efficiency of the two-stage PA is improved from 1.9% to 5.0%. The measured power gain is 18.5 dB. The gain variation with dynamic biasing is less than 1.8 dB. An off-chip memoryless digital predistortion linearizer is also adopted, satisfying the 3GPP wideband code division multiple access (WCDMA) linearity specification by a 10 dB improvement of adjacent channel power ratio (ACPR) at +26 dBm average channel output power. A SiGe PA with dual dynamic bias control and memoryless digital predistortion for WCDMA handset applications Junxiong Deng PS Gudem LE Larson DF Kimball PM Asbeck doi:10.1109/JSSC.2006.872735 Solid-State Circuits, IEEE Journal of, Vol. 41, No. 5. (2006), pp. 1210-1221. 2008-05-05T02:28:54-00:00 2006 Solid-State Circuits, IEEE Journal of 41 5 1210 1221 asbeck dpd handset implementation kimball sige wcdma http://www.citeulike.org/user/nandan/article/1178631 <i>Radio and Wireless Conference, 2004 IEEE (2004), pp. 179-182.</i><br /><br />Nonlinearity characterization is critical to amplifier linearization. It is shown that correlation techniques can be used to provide an estimate of amplifier nonlinearity. The output envelope is cross-correlated with a test sequence generated by forming the product of multiple uncorrelated input sequences, to yield estimates of the low order nonlinearity coefficients. The proposed method can be employed in the background during amplifier operation to estimate amplifier nonlinearity with IS-95 forward-link CDMA signals. Correlation techniques for estimation of amplifier nonlinearity MY Li I Galton LE Larson PM Asbeck Radio and Wireless Conference, 2004 IEEE (2004), pp. 179-182. 2007-03-21T06:07:23-00:00 2004 Radio and Wireless Conference, 2004 IEEE 179 182 no-tag http://www.citeulike.org/user/lchcharles/article/971084 <i>Microwave Theory and Techniques, IEEE Transactions on, Vol. 54, No. 11. (2006), pp. 3848-3856.</i><br /><br />A high-efficiency wideband code-division multiple-access (W-CDMA) base-station amplifier is presented using high-performance GaN heterostrucutre field-effect transistors to achieve high gain and efficiency with good linearity. For high efficiency, class J/E operation was employed, which can attain up to 80% efficiency over a wide range of input powers and power supply voltages. For nonconstant envelope input, the average efficiency is further increased by employing the envelope-tracking architecture using a wide-bandwidth high-efficiency envelope amplifier. The linearity of overall system is enhanced by digital pre-distortion. The measured average power-added efficiency of the amplifier is as high as 50.7% for a W-CDMA modulated signal with peak-to-average power ratio of 7.67 dB at an average output power of 37.2 W and gain of 10.0 dB. We believe that this corresponds to the best efficiency performance among reported base-station power amplifiers for W-CDMA. The measured error vector magnitude is as low as 1.74% with adjacent channel leakage ratio of<tex>$-$</tex>51.0 dBc at an offset frequency of 5 MHz. High-Efficiency Envelope-Tracking W-CDMA Base-Station Amplifier Using GaN HFETs DF Kimball J Jeong C Hsia P Draxler S Lanfranco W Nagy K Linthicum LE Larson PM Asbeck Microwave Theory and Techniques, IEEE Transactions on, Vol. 54, No. 11. (2006), pp. 3848-3856. 2006-12-02T04:22:18-00:00 2006 Microwave Theory and Techniques, IEEE Transactions on 54 11 3848 3856 gan use wcdma