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`A. D. Kim, et. al., “High efficiency and wideband envelope tracking power
`amplifier with sweet spot tracking” 2010 IEEE Radio Frequency
`Inte rated Circuits S mposium, Ma 23 — 25, 2010.
`
`
`PG. Blanken, et. al., “A SOMHZ bandwidth multi-mode PA supply
`
`modulator for GSM, EDGE and UMTS application” 2008 IEEE Radio
`
`
`
`Freuenc Inte rated Circuits S m-osium, June 17, 2008.
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`T. Kwak, et. al., “A 2 W CMOS Hybrid Switching Amplitude Modulator
`
`
`
`for EDGE Polar Transmitters” IEEE Journal of Solid-State Circuits, Vol.
`
`42, Issue 12, December 2007.
`
`
`W. Chu, et. al., “A 10 MHz Bandwidth, 2 mV Ripple PA Regulator for
`
`CDMA Transmitters” IEEE Journal of Solid—State Circuits, Vol. 43, Issue
`
`
`12, December 2008.
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`11. D. Kim, et. al., “High efficiency and wideband envelope tracking power amplifier
`with sweet spot tracking” was published in the 2010 IEEE Radio Frequency
`Integrated Circuits Symposium. The 2010 IEEE Radio Frequency Integrated Circuits
`Symposium was held from May 23 — 25, 2010. Copies of the conference proceedings
`were made available no later than the last day of the conference. The article is
`currently available for public download from the IEEE digital library, IEEE Xplore.
`
`12. P.G. Blanken, et. al., “A SOMHz bandwidth multi-mode PA supply modulator for
`GSM, EDGE and UMTS application” was published in the 2008 IEEE Radio
`Frequency Integrated Circuits Symposium. The 2008 IEEE Radio Frequency
`Integrated Circuits Symposium was held on June 15-17, 2008. Copies of the
`conference proceedings were made available no later than the last day of the
`conference. The article is currently available for public download from the IEEE
`digital library, IEEE Xplore.
`
`13. T. Kwak, et. al., “A 2 W CMOS Hybrid Switching Amplitude Modulator for EDGE
`Polar Transmitters” was published in the IEEE Journal of Solid—State Circuits, Vol.
`42, Issue 12, December 2007. The IEEE Journal of Solid-State Circuits, Vol. 42,
`Issue 12 was published on December 12, 2007. The article is currently available for
`public download from the IEEE digital library, IEEE Xplore
`
`14. W. Chu, et. al., “A 10 MHz Bandwidth, 2 mV Ripple PA Regulator for CDMA
`Transmitters” was published in the IEEE Journal of Solid-State Circuits, Vol. 43,
`Issue 12, December 2008. The IEEE Journal of Solid-State Circuits, Vol. 43, Issue
`12 was published on December 12, 2008. The article is currently available for public
`download from the IEEE digital library, IEEE Xplore
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`EXHIBIT A
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`5/23/2018
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`High efficiency and wideband envelope tracking power
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` Dongsu Kim ;
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` Bumman Kim
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`Abstract:
`This paper describes the implementation of a high efficiency and wideband envelope tracking power amplifier with sweet spot tracking. By
`modulating supply voltage of power amplifier (PA), efficiency can be increased significantly. And linearity is improved by envelope shaping and
`sweet spot tracking. The supply modulator has a combined structure of a switching amplifier and a linear amplifier to achieve high efficiency as well
`as wide bandwidth. The measurement results show efficiencies of 36.4/34.1 % for 10/20 MHz long term evolution (LTE) signals with peak to
`average power ratio (PAPR) of 7.5/7.42 dB.
`
`Published in: Radio Frequency Integrated Circuits Symposium (RFIC), 2010 IEEE
`
`Date of Conference: 23-25 May 2010
`
` INSPEC Accession Number: 11360746
`
`Date Added to IEEE Xplore: 03 June 2010
`
`DOI: 10.1109/RFIC.2010.5477260
`
` ISBN Information:
`
` ISSN Information:
`
`Publisher: IEEE
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`Conference Location: Anaheim, CA, USA
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` Contents
`
`SECTION I.
`Introduction
`
`As wireless communication systems provide high data rate services, the channel bandwidth and
`PAPR of the signals are increased and the efficiency for the power amplifier is decreased. In the
`case of conventional PA with fixed supply voltage (Fig. 1a), the PA should be operated in the back
`off power region to linearly amplify the modulated signal with high PAPR and its efficiency is much
`lower than its peak value as shown in Fig. 2. On the other hand, the envelope tracking PA (Fig. 1b)
`operates under modulated supply voltage according to its output power level and its efficiency is
`degraded slightly.
`
`Because overall efficiency of the envelope tracking PA is proportional to efficiency of the supply
`modulator and its linearity is affected by linearity of the supply modulator, a realization of the
`supply modulator with a high efficiency and good linearity is very important. In [1], they have
`designed a low dropout (LDO) regulator as a supply modulator, but its efficiency is very low for
`
`https://ieeexplore.ieee.org/document/5477260/
`
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`1/8
`
`Attachment A - 1
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`

`5/23/2018
`
` Alerts
`
`High efficiency and wideband envelope tracking power amplifier with sweet spot tracking - IEEE Conference Publication
`high PAPR signals. In [2], a switching amplifier is used as a supply modulator. Although it achieves
`high efficiency, it requires high order passive filter and its bandwidth is too narrow to use for wide
`bandwidth signals such as LTE and WiMAX. To achieve high efficiency and wide bandwidth, we use
`hybrid switching supply modulator combining the advantages of two supply modulators [3][7]. To
`improve the performance of power amplifier, a boost converter is added to the supply modulator as
`shown in Fig. 3. By boosting the supply voltage of the linear amplifier from 3.4V to 5V, the output
`voltage of the supply modulator is increased up to 4.5V and the power amplifier shows higher gain,
`efficiency, output power and wider bandwidth.
`
`In [8], they analyze nonlinear distortion of envelope tracking PA. Because of knee voltage and
`nonlinear capacitance, AM-AM and AM-PM distortion are generated. By adopting envelope
`shaping and sweet spot tracking, linearity can be improved.
`
`In this paper, we implement a high efficiency and wideband envelope tracking PA for LTE
`applications using a hybrid switching supply modulator, HBT PA, envelope shaping, and sweet spot
`tracking.
`
`Fig. 1. (a) Conventional PA with fixed supply voltage. (b) Envelope tracking PA with modulated
`supply voltage.
`
`Fig. 2. PA's efficiency curves with fixed supply voltage and modulated supply voltage.
`
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`High efficiency and wideband envelope tracking power amplifier with sweet spot tracking - IEEE Conference Publication
`
`Fig. 3. Block diagram of the hybrid switching supply modulator with boost converter.
`
`SECTION II.
`Design of High Efficiency and
`Wideband Supply Modulator
`
`The proposed supply modulator consists of a wideband linear amplifier, a high efficiency low speed
`switching amplifier, and a boost converter. Usually the switching amplifier supplies low frequency
`component of the envelope signal with high efficiency and the linear amplifier supplies other high
`frequency component with high speed. Because most of the power of the envelope signal is located
`at a low frequency, this structure is suitable for an operation with high efficiency and wideband.
`
`In Fig. 3, the wideband linear amplifier operates as a voltage-controlled voltage source (VCVS). It
`means the output voltage of the linear amplifier is the same with its input voltage up to tens of MHz
`due to its high gain, wide bandwidth, and negative feedback. As shown in Fig. 4, we use folded-
`cascode OTA as a gain stage to achieve a large bandwidth and high DC gain. For large current
`driving capability and rail-to-rail operation, the output buffer has a common source configuration
`and it is biased as class-AB for linearity and efficiency.
`
`The high efficiency, low speed switching amplifier operates as a dependent current source. It senses
`the direction of the linear amplifier's current and controls the switching amplifier using a hysteretic
`comparator. Generally, the average switching frequency is dependent on the hysteresis width,
`inductor value, and some other parameters for a narrow-band signal. For a wideband signal, the
`average switching frequency is mainly determined by its bandwidth. The sizes of the power
`switches are determined by considering the conduction loss and switching loss at the specific load
`resistance, switching frequency, and duty ratio. For the protection, high efficiency, and low
`switching noise of the switches, anti-shoot-through circuit and divided switches with current
`control technique are employed (Fig. 5) [9]. Gate driver for the divided switches, which is shown in
`Fig. 6, turns on / off the 4 switches with a little delay. It can be designed easily using 4 MUXs and
`inverter chains.
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`5/23/2018
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`High efficiency and wideband envelope tracking power amplifier with sweet spot tracking - IEEE Conference Publication
`
`Fig. 4 Wideband linear amplifier.
`
`Fig. 5 High efficiency switching amplifier.
`
`Fig. 6. Gate driver for divide switches with current control technique.
`
`SECTION III.
`Envelope Shaping and Sweet Spot
`Tracking
`
`The modulated PA operates differently according to the supply voltage level. Especially at a low
`supply voltage, a power amplifier shows severe nonlinear characteristics such as AM-AM and AM-
`PM di
`i
`b
`f k
`l
`ff
`d
`li
`i
`T
`h
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`
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`5/23/2018
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`High efficiency and wideband envelope tracking power amplifier with sweet spot tracking - IEEE Conference Publication
`PM distortions because of knee voltage effect and nonlinear capacitance. To compensate these
`effects, an envelope shaping method should be used [7].
`
`In addition to this basic method, a sweet spot tracking is proposed in this work. Fig. 7 is third-order
`and fifth-order intermodulation distortions (IMD) of PA in two-tone analysis. In this figure, there
`are sweet spots which are local minimums of IMD and are occurred by cancellation of the
`harmonics. As supply voltage decreases, the sweet spot also moves to lower power. By adjusting the
`supply voltage to minimize the distortions at each power level, the linearity of the envelope tracking
`PA can be improved significantly.
`
`Fig. 7. Simulated third-order and fifth-order intermodulation distortions of PA in two-tone
`analysis.
`
`SECTION IV.
`Measurement Results
`
`The designed supply modulator is fabricated using 65nm CMOS process and it uses thick oxide I/O
`devices for a high voltage operation. Chip photograph is shown in Fig. 8 and its size is
`. The supply voltage for the supply modulator is 3.4 V (the battery voltage) and
` (cid:2) C

(cid:2)
`the boost converter generates 5 V for supply of the linear amplifier. In this configuration, output
`voltage range of the supply modulator is 0.5 to 4.5 V regardless of the battery voltage fluctuation,
`replacing the DC-DC converter [10]. The linear amplifier shows over 100 MHz bandwidth and over
`55 dB DC gain. The average switching frequency of the switching amplifier is varied from 3 MHz to
`6 MHz according to the bandwidth of an input signal.
`
`To implement the envelope tracking PA, 2.535GHz class-AB PA, which is fabricated using
`InGaP/GaAs 2um HBT process, is used. It has about 30 dBm peak output power at 3 V supply
`voltage. By boosting the supply voltage of the linear amplifier, PA's supply voltage increases up to
`4.5 V and peak output power of the PA also increases to 33.4 dBm. Performance of the envelope
`tracking PA is measured using 10/20 MHz LTE signals with 7.5/7.42 dB of PAPR.
`
`Fig. 9 shows the measured efficiency and gain of the envelope tracking PA. For the 10 MHz LTE
`signal, the envelope tracking PA has efficiency of 36.4% at output power of 27.2 dBm. For the 20
`MHz LTE signal, its efficiency is 34.1% at output power of 26.1 dBm. Estimated efficiencies of the
`supply modulator are about 75/71% for 10/20 MHz LTE signals. These values can be calculated
`from PA's efficiency curve at each supply voltage. Fig. 10 is measured output spectra of the envelope
`tracking PA at the peak output powers without any linearization technique.
`
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`5/23/2018
`
`High efficiency and wideband envelope tracking power amplifier with sweet spot tracking - IEEE Conference Publication
`
`Fig. 8. Fabricated chip photograph of the supply modulator.
`
`Fig. 9. Measured efficiency and gain of the envelope tracking PA.
`
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`

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`5/23/2018
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`High efficiency and wideband envelope tracking power amplifier with sweet spot tracking - IEEE Conference Publication
`
`Fig. 10. Measured output spectra of the envelope tracking PA at peak output power.
`
`TABLE I Performance Summary of Envelope Tracking Power Amplifier for LTE Applications
`
`10 MHz 20 MHz
`Signal bandwidth
`7.5 dB
`7.42 dB
`PAPR
`3.4 V
`Supply voltage
`27.2 dBm26.1 dBm
`Peak output power
`36.4% 34.1%
`Peak efficiency
`Estimated efficiency of supply modulator @ peak output power75%
`71%
`
`SECTION V.
`Conclusions
`
`A high efficiency and wideband envelope tracking PA with sweet spot tracking technique is
`proposed and implemented for LTE applications. For the supply modulation, a hybrid switching
`supply modulator with boost converter is fabricated using 65nm CMOS process. An envelope
`shaping with sweet spot tracking is adopted to compensate AM-AM and AM-PM distortions.
`Efficiencies of the implemented envelope tracking PA are 36.4/34.1% at output power of 27.2/26.1
`dBm for 10/20 MHz LTE signals, respectively. Measured results show the proposed supply
`modulator with sweet spot tracking is a suitable structure to achieve a high efficiency and wideband
`envelope tracking PA.
`
`ACKNOWLEDGEMENT
`This work was supported by WCU (World Class University) program through the Korea Science and
`Engineering Foundation funded by the Ministry of Education, Science and Technology (Project No.
`R31-2008-000-10100-0), and by the MKE (The Ministry of Knowledge Economy), Korea, under
`the ITRC (Information Technology Research Center) support program supervised by the NIPA
`(National IT Industry Promotion Agency) (NIPA-2009-C1090-0902-0037).
`
`Authors
`
`References
`
`Citations
`
`Keywords
`
`Related Articles
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`High efficiency and wideband envelope tracking power amplifier with sweet spot tracking - IEEE Conference Publication
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`Attachment A - 8
`
`

`

`RMO3D-1
`
`High Efficiency and Wideband Envelope Tracking Power Amplifier
`with Sweet Spot Tracking
`Dongsu Kim, Jinsung Choi, Daehyun Kang, and Bumman Kim
`Department of Electrical Engineering, Pohang University of Science and Technology,
`Pohang, Gyeongbuk, 790-784, Republic of Korea
`
`Abstract — This paper describes the implementation of a
`high efficiency and wideband envelope tracking power
`amplifier with sweet spot tracking. By modulating supply
`voltage of power amplifier (PA), efficiency can be increased
`significantly. And linearity is improved by envelope shaping
`and sweet spot tracking. The supply modulator has a
`combined structure of a switching amplifier and a linear
`amplifier to achieve high efficiency as well as wide
`bandwidth. The measurement results show efficiencies of
`36.4/34.1 % for 10/20 MHz long term evolution (LTE) signals
`with peak to average power ratio (PAPR) of 7.5/7.42 dB.
`Index Terms — Boost converter, envelope tracking, linear
`amplifier, long term evolution (LTE), power amplifier (PA),
`sweet spot, switching amplifier.
`
`3.4V to 5V, the output voltage of the supply modulator is
`increased up to 4.5V and the power amplifier shows
`higher gain, efficiency, output power and wider bandwidth.
`In [8], they analyze nonlinear distortion of envelope
`tracking PA. Because of knee voltage and nonlinear
`capacitance, AM-AM and AM-PM distortion are
`generated. By adopting envelope shaping and sweet spot
`tracking, linearity can be improved.
`In this paper, we implement a high efficiency and
`wideband envelope tracking PA for LTE applications
`using a hybrid switching supply modulator, HBT PA,
`envelope shaping, and sweet spot tracking.
`
`I. INTRODUCTION
`
`As wireless communication systems provide high data
`rate services, the channel bandwidth and PAPR of the
`signals are increased and the efficiency for the power
`amplifier is decreased. In the case of conventional PA
`with fixed supply voltage (Fig. 1a), the PA should be
`operated in the back off power region to linearly amplify
`the modulated signal with high PAPR and its efficiency is
`much lower than its peak value as shown in Fig. 2. On the
`other hand, the envelope tracking PA (Fig. 1b) operates
`under modulated supply voltage according to its output
`power level and its efficiency is degraded slightly.
`Because overall efficiency of the envelope tracking PA
`is proportional to efficiency of the supply modulator and
`its linearity is affected by linearity of the supply
`modulator, a realization of the supply modulator with a
`high efficiency and good linearity is very important. In [1],
`they have designed a low dropout (LDO) regulator as a
`supply modulator, but its efficiency is very low for high
`PAPR signals. In [2], a switching amplifier is used as a
`supply modulator. Although it achieves high efficiency, it
`requires high order passive filter and its bandwidth is too
`narrow to use for wide bandwidth signals such as LTE and
`WiMAX. To achieve high efficiency and wide bandwidth,
`we use hybrid switching supply modulator combining the
`advantages of two supply modulators [3]-[7]. To improve
`the performance of power amplifier, a boost converter is
`added to the supply modulator as shown in Fig. 3. By
`boosting the supply voltage of the linear amplifier from
`
`(a) Conventional PA with fixed supply voltage. (b)
`Fig. 1.
`Envelope tracking PA with modulated supply voltage.
`
`PA’s efficiency curves with fixed supply voltage and
`Fig. 2.
`modulated supply voltage.
`
`978-1-4244-6241-4/978-1-4244-6242-1/
`978-1-4244-6243-8/10/$26.00 © 2010 IEEE
`
`255
`
`2010 IEEE Radio Frequency Integrated Circuits Symposium
`
`Attachment A - 9
`
`

`

`switching frequency, and duty ratio. For the protection,
`high efficiency, and low switching noise of the switches,
`anti-shoot-through circuit and divided switches with
`current control technique are employed (Fig. 5) [9]. Gate
`driver for the divided switches, which is shown in Fig. 6,
`turns on / off the 4 switches with a little delay. It can be
`designed easily using 4 MUXs and inverter chains.
`
`Fig. 4 Wideband linear amplifier.
`
`Fig. 5 High efficiency switching amplifier.
`
`Fig. 6. Gate driver for divide switches with current control
`technique.
`
`Fig. 3. Block diagram of
`modulator with boost converter.
`
`the hybrid switching supply
`
`II. DESIGN OF HIGH EFFICIENCY AND WIDEBAND
`SUPPLY MODULATOR
`
`The proposed supply modulator consists of a wideband
`linear amplifier, a high efficiency low speed switching
`amplifier, and a boost converter. Usually the switching
`amplifier supplies low frequency component of the
`envelope signal with high efficiency and the linear
`amplifier supplies other high frequency component with
`high speed. Because most of the power of the envelope
`signal is located at a low frequency, this structure is
`suitable for an operation with high efficiency and
`wideband.
`In Fig. 3, the wideband linear amplifier operates as a
`voltage-controlled voltage source (VCVS). It means the
`output voltage of the linear amplifier is the same with its
`input voltage up to tens of MHz due to its high gain, wide
`bandwidth, and negative feedback. As shown in Fig. 4, we
`use folded-cascode OTA as a gain stage to achieve a large
`bandwidth and high DC gain. For large current driving
`capability and rail-to-rail operation, the output buffer has a
`common source configuration and it is biased as class-AB
`for linearity and efficiency.
`The high efficiency, low speed switching amplifier
`operates as a dependent current source. It senses the
`direction of the linear amplifier’s current and controls the
`switching amplifier using a hysteretic comparator.
`Generally, the average switching frequency is dependent
`on the hysteresis width, inductor value, and some other
`parameters for a narrow-band signal. For a wideband
`signal,
`the average switching frequency
`is mainly
`determined by its bandwidth. The sizes of the power
`switches are determined by considering the conduction
`loss and switching loss at the specific load resistance,
`
`256
`
`Attachment A - 10
`
`

`

`III. ENVELOPE SHAPING AND SWEET SPOT TRACKING
`
`The modulated PA operates differently according to the
`supply voltage level. Especially at a low supply voltage, a
`power amplifier shows severe nonlinear characteristics
`such as AM-AM and AM-PM distortions because of knee
`voltage effect and nonlinear capacitance. To compensate
`these effects, an envelope shaping method should be used
`[7].
`In addition to this basic method, a sweet spot tracking is
`proposed in this work. Fig. 7 is third-order and fifth-order
`intermodulation distortions (IMD) of PA in two-tone
`analysis. In this figure, there are sweet spots which are
`local minimums of IMD and are occurred by cancellation
`of the harmonics. As supply voltage decreases, the sweet
`spot also moves to lower power. By adjusting the supply
`voltage to minimize the distortions at each power level,
`the linearity of the envelope tracking PA can be improved
`significantly.
`
`from 3 MHz to 6 MHz according to the bandwidth of an
`input signal.
`To implement the envelope tracking PA, 2.535GHz
`class-AB PA, which is fabricated using InGaP/GaAs 2um
`HBT process, is used. It has about 30 dBm peak output
`power at 3 V supply voltage. By boosting the supply
`voltage of the linear amplifier, PA’s supply voltage
`increases up to 4.5 V and peak output power of the PA
`also increases to 33.4 dBm. Performance of the envelope
`tracking PA is measured using 10/20 MHz LTE signals
`with 7.5/7.42 dB of PAPR.
`Fig. 9 shows the measured efficiency and gain of the
`envelope tracking PA. For the 10 MHz LTE signal, the
`envelope tracking PA has efficiency of 36.4 % at output
`power of 27.2 dBm. For the 20 MHz LTE signal, its
`efficiency is 34.1 % at output power of 26.1 dBm.
`Estimated efficiencies of the supply modulator are about
`75/71 % for 10/20 MHz LTE signals. These values can be
`calculated from PA’s efficiency curve at each supply
`voltage. Fig. 10 is measured output spectra of the
`envelope tracking PA at the peak output powers without
`any linearization technique.
`
`Simulated third-order and fifth-order intermodulation
`Fig. 7.
`distortions of PA in two-tone analysis.
`
`IV. MEASUREMENT RESULTS
`
`The designed supply modulator is fabricated using
`65nm CMOS process and it uses thick oxide I/O devices
`for a high voltage operation. Chip photograph is shown in
`Fig. 8 and its size is 2.6 mm (cid:153) 1.7 mm. The supply voltage
`for the supply modulator is 3.4 V (the battery voltage) and
`the boost converter generates 5 V for supply of the linear
`amplifier. In this configuration, output voltage range of
`the supply modulator is 0.5 to 4.5 V regardless of the
`battery voltage
`fluctuation,
`replacing
`the DC-DC
`converter [10]. The linear amplifier shows over 100 MHz
`bandwidth and over 55 dB DC gain. The average
`switching frequency of the switching amplifier is varied
`
`257
`
`Fig. 8.
`
`Fabricated chip photograph of the supply modulator.
`
`Fig. 9. Measured efficiency and gain of the envelope tracking
`PA.
`
`Attachment A - 11
`
`

`

`ACKNOWLEDGEMENT
`
`This work was supported by WCU (World Class
`University) program through the Korea Science and
`Engineering Foundation funded by
`the Ministry of
`Education, Science and Technology (Project No. R31-
`2008-000-10100-0), and by the MKE (The Ministry of
`Knowledge Economy), Korea, under
`the
`ITRC
`(Information Technology Research Center) support
`program supervised by the NIPA (National IT Industry
`Promotion Agency) (NIPA-2009-C1090-0902-0037).
`
`REFERENCES
`
`[5]
`
`[1] P. Reynaert and M. Steyaert, “A 1.75-GHz polar modulated
`CMOS RF power ampli• er for GSM-EDGE,” IEEE J.
`Solid-State Circuits, vol. 40, no. 12, pp. 2598–2608, Dec.
`2005.
`[2] V. Pinon, F. Hasbani, A. Giry, D. Pache, and C. Garnier, “A
`single-chip WCDMA envelope reconstruction LDMOS PA
`with 130MHz switched-mode power supply,” IEEE Int’l
`Solid State Circ. Conf. Dig. Tech. Papers, Feb. 2008, pp.
`564–565.
`[3] T. Kwak, M. Lee, B. Choi, H. Le, and G. Cho, “A 2W
`CMOS hybrid switching amplitude modulator for EDGE
`polar transmitter,” IEEE Int’l Solid State Circ. Conf. Dig.
`Tech. Papers, Feb. 2007, pp. 518–519.
`[4] F. Wang, D. F. Kimball, D. Y. Lie, P. M. Asbeck, and L. E.
`Larson, “A monolithic high-efficiency 2.4-GHz 20-dBm
`SiGe BiCMOS envelope-tracking OFDM power amplifier,”
`IEEE J. Solid-State Circuits, vol. 42, no. 6, pp. 1271–1281,
`June 2007.
`J. Kitchen, W. Chu, I. Deligoz, S. Kiaei, and B. Bakkaloglu,
`“Combined linear and (cid:507)-modulated switched-mode PA
`supply modulator for polar transmitters,” IEEE Int’l Solid
`State Circ. Conf. Dig. Tech. Papers, Feb. 2007, pp. 82–83.
`[6] W. Chu, B. Bakkaloglu, and S. Kiaei, “A 10MHz-
`bandwidth 2mV-ripple PA-supply regulator for CDMA
`transmitters,” IEEE Int’l Solid State Circ. Conf. Dig. Tech.
`Papers, Feb. 2008, pp. 448–449.
`J. Choi, D. Kim, D. Kang, and B. Kim, “A polar transmitter
`with CMOS programmable hysteretic-controlled hybrid
`switching supply modulator for multistandard applications,”
`IEEE Trans. Microw. Theory Tech., vol. 57, no. 7, pp.
`1675-1686, July 2009.
`J. C. Pedro, J. A. Garcia, and P. M. Cabral, “Nonlinear
`Distortion Analysis of Polar Transmitters,” IEEE Trans.
`Microw. Theory Tech., vol. 55, no. 12, pp. 2757–2765, Dec.
`2007.
`[9] S. Sakiyama, J. Kajiwara, M. Kinoshita, K. Satomi, K.
`Ohtani, and A. Matsuzawa, “An on-chip high-efficiency
`and low-noise dc/dc converter using divided switches with
`current control technique,” IEEE Int’l Solid State Circ. Conf.
`Dig. Tech. Papers, 1999, pp. 156-157.
`[10] J. Choi, D. Kim, D. Kang, J. Park, B. Jin, and B. Kim,
`“Envelope Tracking Power Amplifier Robust to Battery
`Depletion,” in IEEE MTT-S Int. Microw. Symp. Dig., May
`2010.
`
`[7]
`
`[8]
`
`Fig. 10. Measured output spectra of the envelope tracking PA
`at peak output power.
`
`TABLE I
`PERFORMANCE SUMMARY OF ENVELOPE TRACKING
`POWER AMPLIFIER FOR LTE APPLICATIONS
`
`Signal bandwidth
`
`PAPR
`
`Supply voltage
`
`10 MHz
`
`7.5 dB
`
`20 MHz
`
`7.42 dB
`
`3.4 V
`
`Peak output power
`
`27.2 dBm
`
`26.1 dBm
`
`Peak efficiency
`
`36.4 %
`
`34.1 %
`
`Estimated efficiency of
`supply modulator
`@ peak output power
`
`75 %
`
`71 %
`
`V. CONCLUSIONS
`
`A high efficiency and wideband envelope tracking PA
`with sweet spot tracking technique is proposed and
`implemented for LTE applications. For
`the supply
`modulation, a hybrid switching supply modulator with
`boost converter is fabricated using 65nm CMOS process.
`An envelope shaping with sweet spot tracking is adopted
`to compensate AM-AM and AM-PM distortions.
`Efficiencies of the implemented envelope tracking PA are
`36.4/34.1 % at output power of 27.2/26.1 dBm for 10/20
`MHz LTE signals, respectively. Measured results show
`the proposed supply modulator with sweet spot tracking is
`a suitable structure to achieve a high efficiency and
`wideband envelope tracking PA.
`
`258
`
`Attachment A - 12
`
`

`

`EXHIBIT B
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`EXHIBIT B
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`5/25/2018
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`A 50MHz bandwidth multi-mode PA supply modulator for GSM, EDGE and UMTS application - IEEE Conference Publication
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`A 50MHz bandwidth multi-mode PA supply modulator for GSM, EDGE and UMTS application - IEEE Conference Publication
`
`Abstract:
`This paper describes the design and measurement results of a supply modulator for a PA for GSM, EDGE and UMTS application. The modulator
`combines a high-bandwid