An Improved Power-Added Efficiency 19-dBm Hybrid Envelope Elimination and Restoration Power Amplifier for 802.11g WLAN Applications
04 Dec 2006-IEEE Transactions on Microwave Theory and Techniques (IEEE)-Vol. 54, Iss: 12, pp 4086-4099
TL;DR: In this paper, a hybrid wideband EER power amplifier for the WLAN 802.11g system is proposed, which shows an overall efficiency of 36% and power-added efficiency of 28% for a WLAN IEEE 802.15.4 signal at 19dBm (80 mW) output power at 2.4 GHz.
Abstract: 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
Citations
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TL;DR: In this paper, a high-efficiency wideband code-division multiple access (W-CDMA) base station amplifier is presented using high-performance GaN heterostructure field effect transistors to achieve high gain and efficiency with good linearity.
Abstract: A high-efficiency wideband code-division multiple-access (W-CDMA) base-station amplifier is presented using high-performance GaN heterostructure 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 507% for a W-CDMA modulated signal with peak-to-average power ratio of 767 dB at an average output power of 372 W and gain of 100 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 174% with adjacent channel leakage ratio of -510 dBc at an offset frequency of 5 MHz
327 citations
TL;DR: A monolithic SiGe BiCMOS envelope-tracking power amplifier is demonstrated for 802.11g OFDM applications at 2.4 GHz with off-chip digital predistortion employed to improve EVM performance.
Abstract: A monolithic SiGe BiCMOS envelope-tracking power amplifier (PA) is demonstrated for 802.11g OFDM applications at 2.4 GHz. The 4-mm2 die includes a high-efficiency high-precision envelope amplifier and a two-stage SiGe HBT PA for RF amplification. Off-chip digital predistortion is employed to improve EVM performance. The two-stage amplifier exhibits 12-dB gain, <5% EVM, 20-dBm OFDM output power, and an overall efficiency (including the envelope amplifier) of 28%.
232 citations
Cites background or methods from "An Improved Power-Added Efficiency ..."
...These losses limit the overall efficiency of the linear amplifier to a maximum of approximately 30% for a typical OFDM waveform [45]....
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...The optimization of this topology for OFDM applications was extensively reviewed in [45]....
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...2(b), which is extensively analyzed in [45]....
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...RF amplifier EVM, as shown in [45], but the effect is reduced...
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TL;DR: A fully integrated switched-capacitor power amplifier that operates on the envelope of a nonconstant envelope modulated signal as an RF-DAC in an EER/Polar architecture to amplify the signal efficiently.
Abstract: A fully integrated switched-capacitor power amplifier (SCPA) utilizes switched-capacitor techniques in an EER/Polar architecture. It operates on the envelope of a nonconstant envelope modulated signal as an RF-DAC in order to amplify the signal efficiently. The measured maximum output power and PAE are 25.2 dBm and 45%, respectively. When amplifying an 802.11g 64-QAM orthogonal frequency-division multiplexing (OFDM) signal, the measured error vector magnitude is 2.6% and the average output power and power-added efficiencies are 17.7 dBm and 27%, respectively.
207 citations
Cites background from "An Improved Power-Added Efficiency ..."
...Pulsewidth modulation (PWM) [8], [11], outphasing [7], [14], [15], and envelope elimination and restoration (EER) [9], [16], [17] are three viable candidates that have been studied extensively for linearizing such switching PAs....
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Patent•
29 Jan 2008TL;DR: In this article, an envelope tracking (ET) method for controlling the delivery of power to radio frequency power amplifiers (RFPAs) is described. But the system is not suitable for the use of a power amplifier.
Abstract: Envelope tracking (ET) methods and systems for controlling the delivery of power to radio frequency power amplifiers (RFPAs). An exemplary ET system includes an RFPA and a wide bandwidth capable and power efficient envelope modulator that includes a first power supplying apparatus and a second power supplying apparatus. The first power supplying apparatus includes a switch-mode converter and a regulator. The first mode converter is operable to dynamically step down a fixed power supply voltage according to amplitude variations in an envelope signal received by the regulator, and use the resulting dynamic power supply signal to power the regulator. The second power supplying apparatus is connected in parallel with the first power supplying apparatus. Depending on a power of an output signal to be generated at an output of the power amplifier, power is supplied to the power amplifier from either or both of the first and second power supplying apparatuses.
204 citations
TL;DR: In this paper, the use of GaN-on-SiC HEMTs in conventional pulse-width modulated switched-mode power converters targeting switching frequencies in the tens of megahertz range was explored.
Abstract: GaN high electron mobility transistors (HEMTs) are well suited for high-frequency operation due to their lower on resistance and device capacitance compared with traditional silicon devices. When grown on silicon carbide, GaN HEMTs can also achieve very high power density due to the enhanced power handling capabilities of the substrate. As a result, GaN-on-SiC HEMTs are increasingly popular in radio-frequency power amplifiers, and applications as switches in high-frequency power electronics are of high interest. This paper explores the use of GaN-on-SiC HEMTs in conventional pulse-width modulated switched-mode power converters targeting switching frequencies in the tens of megahertz range. Device sizing and efficiency limits of this technology are analyzed, and design principles and guidelines are given to exploit the capabilities of the devices. The results are presented for discrete-device and integrated implementations of a synchronous Buck converter, providing more than 10-W output power supplied from up to 40 V with efficiencies greater than 95% when operated at 10 MHz, and greater than 90% at switching frequencies up to 40 MHz. As a practical application of this technology, the converter is used to accurately track a 3-MHz bandwidth communication envelope signal with 92% efficiency.
158 citations
Cites background from "An Improved Power-Added Efficiency ..."
...High-bandwidth supply modulation has typically been accomplished by the use of linear amplifiers with the corresponding efficiency penalty [21], [22]; recently, a purely switching approach using a multiphase converter was demonstrated [23], requiring a complex control scheme finely tuned to enable switching at the required frequencies....
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References
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Book•
31 Mar 1999
TL;DR: In this paper, the authors present a power amplifier design for GHz frequency bands at GHz GHz frequency band with overdrive and overdrive-only overdrive modes, as well as a switch-mode Amplifier for RF applications.
Abstract: Linear PA Design. Conventional High-Efficiency Amplifier Modes. Class AB PAs at GHz Frequencies. Practical Design of Class AB PAs. Overdrive and the Class F Mode. Switching Mode Amplifiers for RF Applications. Switching PA Modes at GHz Frequencies. Signals, Modulation Systems, and PA Nonlinearities. Efficiency Enhancement Techniques. Power Amplifier Bias Circuit Design. Power Amplifier Architecture. PA Linearization Techniques.
2,060 citations
TL;DR: In this article, a load network is synthesized to have a transient response which maximizes power efficiency even if the active device switching times are substantial fractions of the a.c. cycle.
Abstract: The new class of amplifiers described is based on a load network synthesized to have a transient response which maximizes power efficiency even if the active device switching times are substantial fractions of the a.c. cycle. The new class of amplifiers, named `Class E,' is defined and is illustrated by a detailed description and a set of design equations for one simple member of the class. For that circuit the authors measured 96 percent transistor efficiency at 3.9 MHz at 26-W output from a pair of Motorola 2N3735 TO-5 transistors. Advantages of Class E are unusually high efficiency, a priori designability, large reduction in second-breakdown stress, low sensitivity to active-device characteristics, and potential for high-efficiency operation at higher frequencies than previously published Class-D circuits.
1,902 citations
01 Jan 1975
TL;DR: Advantages of Class E are unusually high efficiency, a priori designability, large reduction in second-breakdown stress, low sensitivity to active-device characteristics, and potential for high-efficiency operation at higher frequencies than previously published Class-D circuits.
1,396 citations
TL;DR: In this article, a wide variety of techniques, implementations, and active devices are presented to generate RF/microwave power for wireless communications, but also in applications such as jamming, imaging, RF heating, and miniature dc/dc converters.
Abstract: 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.
1,335 citations
"An Improved Power-Added Efficiency ..." refers background in this paper
...I. INTRODUCTION HIGH-EFFICIENCY radio-frequency (RF) power am-plifiers (PAs) are critical in portable battery-operated wireless communication systems because they can dominate the power consumption in the transmit mode (over 50% for a common wireless local area network (WLAN) transceiver including…...
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Book•
01 Jan 1983
TL;DR: Modern Digital and Analog Communication Systems offers students a superb pedagogical style and every effort is made to give an intuitive insight - rather than just proofs - as well as heuristic explanations of theoretical results wherever possible.
Abstract: From the Publisher:
Lathi's trademark user-friendly and highly readable text presents a complete and modern treatment of communication systems. It begins by introducing students to the basics of communication systems without using probabilistic theory. Only after a solid knowledge basean understanding of how communication systems workhas been built are concepts requiring probability theory covered. This third edition has been thoroughly updated and revised to include expanded coverage of digital communications. New topics discussed include spread-spectrum systems, cellular communication systems, global positioning systems (GPS), and an entire chapter on emerging digital technologies (such as SONET, ISDN, BISDN, ATM, and video compression).
Ideal for the first communication systems course for electrical engineers, Modern Digital and Analog Communication Systems offers students a superb pedagogical style; it consistently does an excellent job of explaining difficult concepts clearly, using prose as well as mathematics. The author makes every effort to give intuitive insightsrather than just proofsas well as heuristic explanations of theoretical results wherever possible. Featuring lucid explanations, well-chosen examples clarifying abstract mathematical results, and excellent illustrations, this unique text is highly informative and easily accessible to students.
Superb pedagogical style The book consistently does an excellent job of explaining difficult concepts clearly, using prose as well as mathematics.
Every effort is made to give an intuitive insight - rather than just proofs - as well as heuristic explanations of theoretical results,wherever possible.
The clear explanations, the well-chosen examples to clarify the abstract mathematical results, and the excellent illustrations make this book highly informative and easily accessible to an average student.
1,154 citations
Additional excerpts
...The required bandwidth of phase signal is much wider than that of baseband signal [ 23 ], as shown in Fig. 2. The...
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