Switching-Converter-Only Multiphase Envelope Modulator With Slew Rate Enhancer for LTE Power Amplifier Applications

Sankman, Joseph; Song, Min Kyu; Ma, Dongsheng

doi:10.1109/tpel.2015.2406710

Cited by 36 publications

(17 citation statements)

References 21 publications

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“…Various structures of the ET power supply have been presented in previous publications, which can be classified into three categories, namely, linear amplifier structure [34], [35], switched-mode converter structure [36]- [42], and switch-linear hybrid (SLH) structure [43]- [50].…”

Section: Et Power Suppliesmentioning

confidence: 99%

A Review of Envelope Tracking Power Supply for Mobile Communication Systems

2017

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Abstract-In modern mobile communication systems, spectral efficient modulation formats have been widely used, which results in the envelope of the radio frequency (RF) signal is variable and having large peak to average power ratio (PAPR). In order to amplify the RF signal without distortion, the linear power amplifier (LPA) is adopted, which is less efficient when powered by constant voltage. Three popular techniques, i.e., Doherty, envelope elimination and restoration (EER), and envelope tracking (ET) techniques, to greatly improve the efficiency of the power amplifiers are analyzed and compared in this paper, and it is shown that the ET technique is the most suitable for future mobile communication systems. In the ET systems, the ET power supply is the key equipment, which dominates the system efficiency. With the development of the mobile communication systems, the bandwidth and the PAPR of the envelope signals are increasing rapidly, which pose severe challenges on the design of the ET power supply. This paper summarizes and sorts the ET power supplies in the literatures, and a detailed comparison is presented to guide the selection of ET power supplies for different applications. Finally, the methods, including soft-switching, slow envelope, and band separation are proposed for further increasing the efficiency of the ET power supply.Index Terms-Band separation, Doherty, envelope elimination and restoration, envelope tracking, power amplifier, slow envelope, supply modulator, soft-switching. I. IntroductIonT HE mobile communication brings convenience of real-time communicating to people in a mobile state without physical transmission line, and it has been continuously developing ever since its advent in 1970s [1]. The first-generation (1G) mobile communication systems adopted analog electronics technology and can only provide voice service. Furthermore, it suffered poor anti-interference ability and slow data transmission rate. The second-generation (2G) mobile communication systems employed digital electronics technology, and they can transmit and receive voice and text message. With the rapidly increased customers and the demand for multi-media service, the data transmission rate is required to be faster, and the third-generation (3G) and fourth-generation (4G) mobile communication systems emerged in succession, which makes the video calling service and internet surfing into reality [1].With the development of mobile communication, the power consumption increases rapidly, accounting for about 10% of the global power generation. Thus, it is necessary to reduce the power consumption of the mobile communication. In mobile communication systems, the base stations consume the majority of the power. In a base station, about 50% of the power is consumed by the power amplifier, and its loss is dissipated as heat, which requires extra power to cool down. So, increasing the efficiency of the power amplifier is the basis of reducing the overall power consumption of the mobile communication.In 2G mobile communicatio...

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Section: Et Power Suppliesmentioning

confidence: 99%

A Review of Envelope Tracking Power Supply for Mobile Communication Systems

2017

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“…On the other hand, switching amplifiers provide high efficiency at all power levels, but their bandwidth is too [16]. Recently reported switching amplifiers utilize multiphase and slew rate enhancement to achieve a medium bandwidth [17]. However, several design issues including equal current sharing among different stages and increased switching losses need to be addressed.…”

Section: Dissertation Outlinementioning

confidence: 99%

“…When EN is high and ENB is low, R = RC + Rh and … = … ; When EN is low and ENB is high, R † = RC and … † = Rh + … . According to (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18), the latter scenario reduces OTA's dc gain to ensure stability in case of a large PA equivalent resistance seen by the hybrid ET supply modulator.…”

Section: )(3-17)(3-18)mentioning

confidence: 99%

A High Slew-Rate Adaptive Biasing Hybrid Envelope Tracking Supply Modulator for LTE Applications

Yue

Bakkaloglu

2017

IEEE Trans. Microwave Theory Techn.

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As wireless communication enters smartphone era, more complicated communication technologies are being used to transmit higher data rate. Power amplifier (PA) has to work in back-off region, while this inevitably reduces battery life for cellphones.Various techniques have been reported to increase PA efficiency, such as envelope elimination and restoration (EER) and envelope tracking (ET). However, state of the art ET supply modulators failed to address high efficiency, high slew rate, and accurate tracking concurrently.In this dissertation, a linear-switch mode hybrid ET supply modulator utilizing adaptive biasing and gain enhanced current mirror operational transconductance amplifier (OTA) with class-AB output stage in parallel with a switching regulator is presented. In comparison to a conventional OTA design with similar quiescent current consumption, proposed approach improves positive and negative slew rate from 50 V/µs to 93.4 V/µs and -87 V/µs to -152.5 V/µs respectively, dc gain from 45 dB to 67 dB while consuming same amount of quiescent current. The proposed hybrid supply modulator achieves 83% peak efficiency, power added efficiency (PAE) of 42.3% at 26.2 dBm for a 10 MHz 7.24 dB peak-to-average power ratio (PAPR) LTE signal and improves PAE by 8% at 6 dB back off from 26.2 dBm power amplifier (PA) output power with respect to fixed supply. With a 10 MHz 7.24 dB PAPR QPSK LTE signal the ET PA system achieves adjacent channel leakage ratio (ACLR) of -37.7 dBc and error vector magnitude (EVM) of 4.5% at 26.2 dBm PA output power, while with a 10 MHz 8.15 dB PAPR 64QAM LTE signal the ET PA system achieves ACLR of -35.6 dBc and EVM of 6% at 26 dBm PA output power ii without digital pre-distortion (DPD). The proposed supply modulator core circuit occupies 1.1 mm 2 die area, and is fabricated in a 0.18 µm CMOS technology.iii To My Parents and Family iv ACKNOWLEDGMENTS

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“…In [2][3][4][5], where the principles of SPA implementation are considered, the problem of envelope signal harmonic distortions caused by imperfect features of transistors (non-zero switching time, forward on voltage drop, influence of parasitic inductance of outputs of transistors and elements of the printed circuit board, etc.) isn't raised.…”

Section: Introductionmentioning

confidence: 99%

A time-reduced method for calculation distortions in envelope tracking power amplifiers

Pergushev¹,

Sorotsky²

2018

Instrumentation Engineering, Electronics and Telecommunications

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Pergushev A. O., Sorotsky V. A. "A time-reduced method for calculation distortions in envelope tracking power amplifiers" To increase the efficiency of power amplifiers in wireless telecommunications systems, whose signals have a high peak to average power ratio, the envelope tracking method can be used. This method involves forming of a low-frequency envelope signal by a switched-mode power amplifier (SPA), which is then used as a supply voltage for a RF power amplifier. A specific feature of the SPA is that its output signal has high level of harmonic distortions. To evaluate these harmonic distortions, computer simulation can be used. However, time required to perform one cycle of simulation can be as much as several hours because of high complexity of SPA models. To reduce the simulation time of signal spectrum, approximate method that allows to represent the output voltage of a SPA in analytical form can be used. However, in known publications, the non-zero switching time of transistors is not taken into consideration, which leads to an appreciable error in the determination of the spectral components. This paper presents a method of analytic calculation of SPA output signal spectrum that considers the linear and exponential approximations of non-zero switching times of transistor. It allows to decrease the error in determining the harmonic distortions from 30…35 dB to 1…6 dB and to reduce the time expenditure as compared with computer simulation as much as 300 through 800 times.

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Switching-Converter-Only Multiphase Envelope Modulator With Slew Rate Enhancer for LTE Power Amplifier Applications

Cited by 36 publications

References 21 publications

A Review of Envelope Tracking Power Supply for Mobile Communication Systems

A Review of Envelope Tracking Power Supply for Mobile Communication Systems

A High Slew-Rate Adaptive Biasing Hybrid Envelope Tracking Supply Modulator for LTE Applications

A time-reduced method for calculation distortions in envelope tracking power amplifiers

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