Optimization for Envelope Shaped Operation of Envelope Tracking Power Amplifier

Kim, Dong–Su; Kang, Daehyun; Choi, Jinsung; Kim, Jooseung; Cho, Yunsung; Kim, Bumman

doi:10.1109/tmtt.2011.2140124

Cited by 106 publications

(56 citation statements)

References 25 publications

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“…The power amplifier in the EER technique can achieve the highest efficiency, which could exceed 80% due to the adoption of NLPA. The LPA in ET technique could achieve 78.5% efficiency at high output power level when the LPA is biased at class B, and the efficiency decreases at low output power region due to the adoption of the envelope shaping [31]- [33], which results in the amplitude of the shaped envelope signal is higher than that of the original envelope signal. The efficiency curve of the Doherty amplifier is piecewise.…”

Section: Comparison Of the Three Techniquesmentioning

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: Comparison Of the Three Techniquesmentioning

confidence: 99%

A Review of Envelope Tracking Power Supply for Mobile Communication Systems

2017

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“…To properly evaluate the bias modulator, applying the PA as the load is the most accurate way. However, that needs considerable computation time on simulation or is prone to cause convergence error [15].…”

Section: Bias Modulator Designmentioning

confidence: 99%

“…Low drop-out regulators and switching regulators are not good choice for the bias modulator due to low efficiency and narrow bandwidth, respectively [3,4]. The hybrid bias modulators, which have a highly efficient switching stage and a broadband linear stage, have been popular for the ET applications [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22]. The switching stage supplies most of the current which are around very low frequency including DC.…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, the bias modulators, which are generally designed using CMOS process, have been generally applied to those PAs using GaAs HBT or SiGe BiCMOS processes for higher performance [13][14][15][16][17][18][19][20]. However, the PAs based on CMOS process has great advantages in lower cost and higher integration in spite of its relatively poor performances [23][24][25].…”

Section: Introductionmentioning

confidence: 99%

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A CMOS Envelope Tracking Power Amplifier for LTE Mobile Applications

Ham¹,

Jung²,

Kim³

et al. 2014

JSTS:Journal of Semiconductor Technology and Science

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Abstract-This paper presents an envelope tracking power amplifier using a standard CMOS process for the 3GPP long-term evolution transmitters. An efficiency of the CMOS power amplifier for the modulated signals can be improved using a highly efficient and wideband CMOS bias modulator. The CMOS PA is based on a two-stage differential common-source structure for high gain and large voltage swing. The bias modulator is based on a hybrid buck converter which consists of a linear stage and a switching stage. The dynamic load condition according to the envelope signal level is taken into account for the bias modulator design. By applying the bias modulator to the power amplifier, an overall efficiency of 41.7 % was achieved at an output power of 24 dBm using the 16-QAM uplink LTE signal. It is 5.3 % points higher than that of the power amplifier alone at the same output power and linearity.

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“…To generate the dynamically varying bias voltage for PAs, the ET technique requires a BM that has high speed and high current supplying capability. A hybrid buck converter which consists of a linear stage and a switching stage has been generally used [2][3][4][5][6][7][8][9].…”

Section: Introductionmentioning

confidence: 99%

Dual Bias Modulator for Envelope Tracking and Average Power Tracking Modes for CMOS Power Amplifier

Ham¹,

Jung²,

Bae³

et al. 2014

JSTS:Journal of Semiconductor Technology and Science

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Abstract-This paper presents a dual-mode bias modulator (BM) for complementary metal oxide semiconductor (CMOS) power amplifiers (PAs). The BM includes a hybrid buck converter and a normal buck converter for an envelope tracking (ET) mode for high output power and for an average power tracking (APT) mode for low output power, respectively. The dual-mode BM and CMOS PA are designed using a 0.18-mm CMOS process for the 1.75 GHz band. For the 16-QAM LTE signal with a peakto-average power ratio of 7.3 dB and a bandwidth of 5 MHz, the PA with the ET mode exhibited a poweradded efficiency (PAE) of 39.2%, an EVM of 4.8%, a gain of 19.0 dB, and an adjacent channel leakage power ratio of -30 dBc at an average output power of 22 dBm, while the stand-alone PA has a PAE of 8% lower at the same condition. The PA with APT mode has a PAE of 21.3%, which is an improvement of 13.4% from that of the stand-alone PA at an output power of 13 dBm.

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Optimization for Envelope Shaped Operation of Envelope Tracking Power Amplifier

Cited by 106 publications

References 25 publications

A Review of Envelope Tracking Power Supply for Mobile Communication Systems

A Review of Envelope Tracking Power Supply for Mobile Communication Systems

A CMOS Envelope Tracking Power Amplifier for LTE Mobile Applications

Dual Bias Modulator for Envelope Tracking and Average Power Tracking Modes for CMOS Power Amplifier

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