A K/Ka-band series Doherty CMOS power amplifier with distributed multi-step impedance inverting network

Xinyu Jiang; Wei Deng; Junlong Gong; Haikun Jia; Baoyong Chi

doi:10.1088/1674-4926/25010002

J. Semicond. > 2025, Volume 46 > Issue 6 > 062201

SPECIAL TOPIC ARTICLES

A K/Ka-band series Doherty CMOS power amplifier with distributed multi-step impedance inverting network

Xinyu Jiang, Wei Deng, Junlong Gong, Haikun Jia and Baoyong Chi

+ Author Affiliations

Corresponding author: Wei Deng, wdeng@tsinghua.edu.cn

DOI: 10.1088/1674-4926/25010002CSTR: 32376.14.1674-4926.25010002

Abstract: A two-way K/Ka-band series-Doherty PA (SDPA) with a distributed impedance inverting network (IIN) for millimeter wave applications is presented in this article. The proposed distributed IIN contributes to achieve wideband linear and power back-off (PBO) efficiency enhancement. Implemented in 65 nm bulk CMOS technology, this work realizes a measured 3 dB bandwidth of 15.5 GHz with 21.2 dB peak small-signal gain at 34.2 GHz. Under 1-V power supply, it achieves OP_1dB over 13.4 dBm and P_sat over 16 dBm between 21 to 30 GHz. The measured maximum P_sat, OP_1dB, peak/OP_1dB/6dB_PBO PAE results are 17.5, 14.7 dBm, and 28.2%/23.2%/13.2%. Without digital pre-distortion (DPD) and equalization, EVMs are lower than −25.2 dB for 200 MHz 64-QAM signals. Besides, this work achieves −33.35, −23.52, and −20 dB EVMs for 100 MHz 256-QAM, 600 MHz 64-QAM and 2 GHz 16-QAM signals at 27 GHz without DPD and equalization.

Key words: Doherty PA, load modulation, broadband, transformer, linear enhancement, efficiency enhancement

References

[1]	Pashaeifar M, de Vreede L C N, Alavi M S. A millimeter-wave CMOS series-Doherty power amplifier with post-silicon inter-stage passive validation. IEEE J Solid State Circuits, 2022, 57(10), 2999 doi: 10.1109/JSSC.2022.3175685
[2]	Wang Y, Xu H T. Millimeter-wave PA design techniques in ISSCC 2024. J Semicond, 2024, 45(4), 040205 doi: 10.1088/1674-4926/45/4/040205
[3]	Li S S, Huang M Y, Jung D, et al. A MM-wave current-mode inverse outphasing transmitter front-end: A circuit duality of conventional voltage-mode outphasing. IEEE J Solid State Circuits, 2021, 56(6), 1732 doi: 10.1109/JSSC.2020.3038882
[4]	Rabet B, Asbeck P M. A 28 GHz single-input linear chireix (SILC) power amplifier in 130 nm SiGe technology. IEEE J Solid State Circuits, 2020, 55(6), 1482 doi: 10.1109/JSSC.2020.2967542
[5]	Anabtawi N, Ferzli R, Harmanani H M. A single switcher combined series parallel hybrid envelope tracking amplifier for wideband RF power amplifier applications. 2016 IEEE International Symposium on Circuits and Systems (ISCAS), 2016, 2366 doi: 10.1109/ISCAS.2016.7539060
[6]	Chowdhury D, Mundlapudi S R, Afsahi A. A fully integrated reconfigurable wideband envelope-tracking SoC for high-bandwidth WLAN applications in a 28nm CMOS technology. 2017 IEEE International Solid-State Circuits Conference (ISSCC), 2017, 34 doi: 10.1109/ISSCC.2017.7870247
[7]	Qunaj V, Reynaert P. A ka-band Doherty-like LMBA for high-speed wireless communication in 28-nm CMOS. IEEE J Solid State Circuits, 2021, 56(12), 3694 doi: 10.1109/JSSC.2021.3110168
[8]	Huang X R, Jia H K, Deng W, et al. A compact E-band load-modulation balanced power amplifier in 65-nm CMOS. IEEE J Solid State Circuits, 2024, 59(10), 3172 doi: 10.1109/JSSC.2024.3404610
[9]	Rostomyan N, Özen M, Asbeck P. 28 GHz Doherty power amplifier in CMOS SOI with 28% back-off PAE. IEEE Microw Wirel Compon Lett, 2018, 28(5), 446 doi: 10.1109/LMWC.2018.2813882
[10]	Park H C, Kim S, Lee J, et al. Single transformer-based compact Doherty power amplifiers for 5G RF phased-array ICs. IEEE J Solid State Circuits, 2022, 57(5), 1267 doi: 10.1109/JSSC.2022.3148044
[11]	Cripps S C. RF power amplifiers for wireless communications, 2nd ed. Norwood, MA: Artech House, 2006
[12]	Yi Y R, Zhao D X, Zhang J J, et al. A 24–30 GHz 8-element dual-polarized 5g Fr2 phased-array transceiveric with 20.8-dBm tx OP1dB and 4.1-dB rx NFin 65-nm cmos. J Semicond, 2024, 45(1), 012201 doi: 10.1088/1674-4926/45/1/012201
[13]	Jia H K, Prawoto C C, Chi B Y, et al. A full ka-band power amplifier with 32.9% PAE and 15.3-dBm power in 65-nm CMOS. IEEE Trans Circuits Syst I Regul Pap, 2018, 65(9), 2657 doi: 10.1109/TCSI.2018.2799983
[14]	Wang R T, Li C G, Qiu K Q, et al. A ka-band broadband power amplifier with transformer-based lossy magnetically coupled resonator network: Analysis and design. IEEE Trans Microw Theory Tech, 2024, 72(12), 6857 doi: 10.1109/TMTT.2024.3411485
[15]	Gong J, Li W, Hu J T, et al. An 8–18 GHz power amplifier with novel gain fluctuation compensation technique in 65 nm CMOS. J Semicond, 2018, 39(12), 125008 doi: 10.1088/1674-4926/39/12/125008
[16]	Chan W L, Long J R. A 58–65 GHz neutralized CMOS power amplifier with PAE above 10% at 1-V supply. IEEE J Solid State Circuits, 2010, 45(3), 554 doi: 10.1109/JSSC.2009.2039274
[17]	Hu S, Wang F, Wang H. A 28-/37-/39-GHz linear Doherty power amplifier in silicon for 5G applications. IEEE J Solid State Circuits, 2019, 54(6), 1586 doi: 10.1109/JSSC.2019.2902307
[18]	Wang F, Wang H. A high-power broadband multi-primary DAT-based Doherty power amplifier for mm-wave 5G applications. IEEE J Solid State Circuits, 2021, 56(6), 1668 doi: 10.1109/JSSC.2021.3070800
[19]	Zhang X H, Li S S, Huang D Q, et al. A millimeter-wave three-way Doherty power amplifier for 5G NR OFDM. IEEE J Solid State Circuits, 2023, 58(5), 1256 doi: 10.1109/JSSC.2023.3238766
[20]	Kulkarni S, Zhao D X, Reynaert P. Design of an optimal layout polyphase filter for millimeter-wave quadrature LO generation. IEEE Trans Circuits Syst II Express Briefs, 2013, 60(4), 202 doi: 10.1109/TCSII.2013.2251946
[21]	Koh K J, Rebeiz G M. 0.13-μm CMOS phase shifters for X-, Ku-, and K-band phased arrays. IEEE J Solid State Circuits, 2007, 42(11), 2535 doi: 10.1109/JSSC.2007.907225
[22]	Indirayanti P, Reynaert P. A 32 GHz 20 dBm-PSAT transformer-based Doherty power amplifier for multi-Gb/s 5G applications in 28 nm bulk CMOS. 2017 IEEE Radio Frequency Integrated Circuits Symposium (RFIC), 2017, 45 doi: 10.1109/RFIC.2017.7969013
[23]	Fang X H, Xia J J, Boumaiza S. A 28-GHz beamforming Doherty power amplifier with enhanced AM-PM characteristic. IEEE Trans Microw Theory Tech, 2020, 68(7), 3017 doi: 10.1109/TMTT.2020.2968318
[24]	Yu C Y, Feng J, Zhao D X. A 28-GHz Doherty power amplifier with a compact transformer-based quadrature hybrid in 65-nm CMOS. IEEE Trans Circuits Syst II Express Briefs, 2021, 68(8), 2790 doi: 10.1109/TCSII.2021.3068473

Fig. 1. (Color online) Two-way PDPA’s. (a) Simplified model; (b) drain efficiency performance; (c) λ/4 T-line based IIN’s ITR.

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Fig. 2. (Color online) Typical methods of two-way power combiner. (a) Series power combiner; (b) parallel power combiner.

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Fig. 3. (Color online) The characterization of pseudo-differential CS amplifier. (a) Simplified circuit; (b) small signal equivalent circuit; (c) simulated Z_opt* vs transistor’s multiplier.

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Fig. 4. (Color online) Transformer-based two-way power combiner for Doherty PA. (a) Series power combiner; (b) parallel power combiner.

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Fig. 5. (Color online) Frequence performances of Zmain. (a) Without LC resonators; (b) with LC resonators.

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Fig. 6. (Color online) Simplified form of (a) SDPA and (b) SDPA’s IIN; (c) inversion paths of ideal λ/4 T-Line and IINs; (d) IINs based on lumped-elements.

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Fig. 7. (Color online) Simulated (a) S₂₁ and (b) S₁₁ of different lumped-elements based IINs.

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Fig. 8. (Color online) Equivalence relations between C−L−C π network and (a) the transmission line; (b) the lumped-element model of transformer; (c) coupler-based network.

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Fig. 9. (Color online) The implementation procedure and result of the distributed IIN. (a) The multi-step IIN; (b) the insertion of two ideal baluns; (c) the final replacement.

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Fig. 10. (Color online) IIN’s phase shift performance at (a) 6 dB PBO; (b) 0 dB PBO; and (c) AM–PM distortion.

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Fig. 11. (Color online) The simulated effective load impedances of two paths at (a) 26 GHz; (b) 27 GHz; (c) 28 GHz; (d) 29 GHz.

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Fig. 12. (Color online) The EM model of series-Doherty power combiner.

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Fig. 13. (Color online) The simulated passive efficiency of the output network at (a) 26 GHz; (b) 27 GHz; (c) 28 GHz; (d) 29 GHz.

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Fig. 14. (Color online) The schematic of the proposed (a) SDPA; (b) ABN; and (c) the frequency response of ABN.

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Fig. 15. (Color online) The EM model of (a) QHC; (b) input IMB; (c) inter IMB.

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Fig. 16. (Color online) Die micrograph of the proposed SDPA.

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Fig. 17. (Color online) Measured S-parameters.

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Fig. 18. (Color online) Simplified (a) small CW signal; (b) large CW signal; (c) modulation measurement setups.

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Fig. 19. (Color online) Measured P_sat and OP1dB vs freq (limited by signal generator, results only cover frequencies below 30 GHz).

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Fig. 20. (Color online) Measured peak/OP1dB/6dBPBO PAEs vs freq (limited by signal generator, results only cover frequencies below 30 GHz).

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Fig. 21. (Color online) Measured output power and PAE at (a) 24 GHz; (b) 26 GHz; (c) 27 GHz; (d) 28 GHz.

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Fig. 22. (Color online) Measured constellations/spectrums under 200 MHz 64-QAM at (a) 22 GHz; (b) 27 GHz; (c) 31 GHz.

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Fig. 23. (Color online) Measured results at 27 GHz under (a) 100 MHz 256-QAM; (b) 600 MHz 64-QAM; (c) 2 GHz 16-QAM.

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Table 1. Performance comparison.

Design parameters	RFIC 2017^[22]	TMTT 2020^[²³^]	TCAS-II 2021^[²⁴^]	This work
Topology	Two-way PDPA	Two-way PDPA	Two-way PDPA	Two-way SDPA
Technology	28 nm bulk	45 nm SOI	65 nm bulk	65 nm bulk
Supply (V)	1	1.5	2	1
3 dB bandwidth (GHz)	29−35*(18.8%)	25.5−36*(34.1%)	25.6−29.4(13.8%)	21.5−37(53.0%)
Core area (mm²)	0.59	1.5	0.35	0.28
Max gain (dB)	22	16.8	20.4	21.2
P_sat (dBm)	19.8	18.2	17.5	17.5
OP_1dB (dBm)	16	15.7	17	14.7
PAE_max (%)	21	22	27	28.2
PAE@OP_1dB (%)	12.8	16.5	27*	23.2
PAE@6dB_PBO (%)	9	9.5	18.7	13.2
*Graphically estimated.

DownLoad: CSV

[1]	Pashaeifar M, de Vreede L C N, Alavi M S. A millimeter-wave CMOS series-Doherty power amplifier with post-silicon inter-stage passive validation. IEEE J Solid State Circuits, 2022, 57(10), 2999 doi: 10.1109/JSSC.2022.3175685
[2]	Wang Y, Xu H T. Millimeter-wave PA design techniques in ISSCC 2024. J Semicond, 2024, 45(4), 040205 doi: 10.1088/1674-4926/45/4/040205
[3]	Li S S, Huang M Y, Jung D, et al. A MM-wave current-mode inverse outphasing transmitter front-end: A circuit duality of conventional voltage-mode outphasing. IEEE J Solid State Circuits, 2021, 56(6), 1732 doi: 10.1109/JSSC.2020.3038882
[4]	Rabet B, Asbeck P M. A 28 GHz single-input linear chireix (SILC) power amplifier in 130 nm SiGe technology. IEEE J Solid State Circuits, 2020, 55(6), 1482 doi: 10.1109/JSSC.2020.2967542
[5]	Anabtawi N, Ferzli R, Harmanani H M. A single switcher combined series parallel hybrid envelope tracking amplifier for wideband RF power amplifier applications. 2016 IEEE International Symposium on Circuits and Systems (ISCAS), 2016, 2366 doi: 10.1109/ISCAS.2016.7539060
[6]	Chowdhury D, Mundlapudi S R, Afsahi A. A fully integrated reconfigurable wideband envelope-tracking SoC for high-bandwidth WLAN applications in a 28nm CMOS technology. 2017 IEEE International Solid-State Circuits Conference (ISSCC), 2017, 34 doi: 10.1109/ISSCC.2017.7870247
[7]	Qunaj V, Reynaert P. A ka-band Doherty-like LMBA for high-speed wireless communication in 28-nm CMOS. IEEE J Solid State Circuits, 2021, 56(12), 3694 doi: 10.1109/JSSC.2021.3110168
[8]	Huang X R, Jia H K, Deng W, et al. A compact E-band load-modulation balanced power amplifier in 65-nm CMOS. IEEE J Solid State Circuits, 2024, 59(10), 3172 doi: 10.1109/JSSC.2024.3404610
[9]	Rostomyan N, Özen M, Asbeck P. 28 GHz Doherty power amplifier in CMOS SOI with 28% back-off PAE. IEEE Microw Wirel Compon Lett, 2018, 28(5), 446 doi: 10.1109/LMWC.2018.2813882
[10]	Park H C, Kim S, Lee J, et al. Single transformer-based compact Doherty power amplifiers for 5G RF phased-array ICs. IEEE J Solid State Circuits, 2022, 57(5), 1267 doi: 10.1109/JSSC.2022.3148044
[11]	Cripps S C. RF power amplifiers for wireless communications, 2nd ed. Norwood, MA: Artech House, 2006
[12]	Yi Y R, Zhao D X, Zhang J J, et al. A 24–30 GHz 8-element dual-polarized 5g Fr2 phased-array transceiveric with 20.8-dBm tx OP1dB and 4.1-dB rx NFin 65-nm cmos. J Semicond, 2024, 45(1), 012201 doi: 10.1088/1674-4926/45/1/012201
[13]	Jia H K, Prawoto C C, Chi B Y, et al. A full ka-band power amplifier with 32.9% PAE and 15.3-dBm power in 65-nm CMOS. IEEE Trans Circuits Syst I Regul Pap, 2018, 65(9), 2657 doi: 10.1109/TCSI.2018.2799983
[14]	Wang R T, Li C G, Qiu K Q, et al. A ka-band broadband power amplifier with transformer-based lossy magnetically coupled resonator network: Analysis and design. IEEE Trans Microw Theory Tech, 2024, 72(12), 6857 doi: 10.1109/TMTT.2024.3411485
[15]	Gong J, Li W, Hu J T, et al. An 8–18 GHz power amplifier with novel gain fluctuation compensation technique in 65 nm CMOS. J Semicond, 2018, 39(12), 125008 doi: 10.1088/1674-4926/39/12/125008
[16]	Chan W L, Long J R. A 58–65 GHz neutralized CMOS power amplifier with PAE above 10% at 1-V supply. IEEE J Solid State Circuits, 2010, 45(3), 554 doi: 10.1109/JSSC.2009.2039274
[17]	Hu S, Wang F, Wang H. A 28-/37-/39-GHz linear Doherty power amplifier in silicon for 5G applications. IEEE J Solid State Circuits, 2019, 54(6), 1586 doi: 10.1109/JSSC.2019.2902307
[18]	Wang F, Wang H. A high-power broadband multi-primary DAT-based Doherty power amplifier for mm-wave 5G applications. IEEE J Solid State Circuits, 2021, 56(6), 1668 doi: 10.1109/JSSC.2021.3070800
[19]	Zhang X H, Li S S, Huang D Q, et al. A millimeter-wave three-way Doherty power amplifier for 5G NR OFDM. IEEE J Solid State Circuits, 2023, 58(5), 1256 doi: 10.1109/JSSC.2023.3238766
[20]	Kulkarni S, Zhao D X, Reynaert P. Design of an optimal layout polyphase filter for millimeter-wave quadrature LO generation. IEEE Trans Circuits Syst II Express Briefs, 2013, 60(4), 202 doi: 10.1109/TCSII.2013.2251946
[21]	Koh K J, Rebeiz G M. 0.13-μm CMOS phase shifters for X-, Ku-, and K-band phased arrays. IEEE J Solid State Circuits, 2007, 42(11), 2535 doi: 10.1109/JSSC.2007.907225
[22]	Indirayanti P, Reynaert P. A 32 GHz 20 dBm-PSAT transformer-based Doherty power amplifier for multi-Gb/s 5G applications in 28 nm bulk CMOS. 2017 IEEE Radio Frequency Integrated Circuits Symposium (RFIC), 2017, 45 doi: 10.1109/RFIC.2017.7969013
[23]	Fang X H, Xia J J, Boumaiza S. A 28-GHz beamforming Doherty power amplifier with enhanced AM-PM characteristic. IEEE Trans Microw Theory Tech, 2020, 68(7), 3017 doi: 10.1109/TMTT.2020.2968318
[24]	Yu C Y, Feng J, Zhao D X. A 28-GHz Doherty power amplifier with a compact transformer-based quadrature hybrid in 65-nm CMOS. IEEE Trans Circuits Syst II Express Briefs, 2021, 68(8), 2790 doi: 10.1109/TCSII.2021.3068473

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Received: 06 January 2025 Revised: 21 February 2025 Online: Accepted Manuscript: 18 March 2025Uncorrected proof: 09 April 2025Published: 05 June 2025

Article Navigation > Journal of Semiconductors > 2025 > 46(6): 062201

Xinyu Jiang, Wei Deng, Junlong Gong, Haikun Jia, Baoyong Chi. A K/Ka-band series Doherty CMOS power amplifier with distributed multi-step impedance inverting network[J]. Journal of Semiconductors, 2025, 46(6): 062201. doi: 10.1088/1674-4926/25010002 ****X Y Jiang, W Deng, J L Gong, H K Jia, and B Y Chi, A K/Ka-band series Doherty CMOS power amplifier with distributed multi-step impedance inverting network[J]. J. Semicond., 2025, 46(6), 062201 doi: 10.1088/1674-4926/25010002

Citation:

Xinyu Jiang, Wei Deng, Junlong Gong, Haikun Jia, Baoyong Chi. A K/Ka-band series Doherty CMOS power amplifier with distributed multi-step impedance inverting network[J]. Journal of Semiconductors, 2025, 46(6): 062201. doi: 10.1088/1674-4926/25010002 ****

X Y Jiang, W Deng, J L Gong, H K Jia, and B Y Chi, A K/Ka-band series Doherty CMOS power amplifier with distributed multi-step impedance inverting network[J]. J. Semicond., 2025, 46(6), 062201 doi: 10.1088/1674-4926/25010002

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A K/Ka-band series Doherty CMOS power amplifier with distributed multi-step impedance inverting network

DOI: 10.1088/1674-4926/25010002

CSTR: 32376.14.1674-4926.25010002

School of Integrated Circuits, Tsinghua University, Beijing 100084, China

More Information

Xinyu Jiang received the B.S. degree from Harbin Institute of Technology, Harbin, China, in 2022. She is currently pursuing the M.S. degree in Tsinghua University. Her research interests include mm-wave integrated circuits, phased array systems and wireless transceiver design
Wei Deng received the B.S. and M.S. degrees from the University of Electronic Science and Technology of China, China, and the Ph.D. degree from Tokyo Institute of Technology, Japan. Currently, he is with the Tsinghua University as an Associate Professor. Dr. Deng is a TPC Member of ISSCC, VLSI, RFIC, CICC, A-SSCC and ESSCIRC. He has been an Associate Editor and a Guest Editor of the SSCL, a Guest Editor of JSSC, and a Distinguished Lecturer of the IEEE SSCS. His research interests include RF, mm-wave, terahertz, and mixed-signal integrated circuits and systems for wireless communications and radars
Corresponding author: wdeng@tsinghua.edu.cn
Received Date: 2025-01-06
Revised Date: 2025-02-21

Available Online: 2025-03-18

Abstract

Abstract

A two-way K/Ka-band series-Doherty PA (SDPA) with a distributed impedance inverting network (IIN) for millimeter wave applications is presented in this article. The proposed distributed IIN contributes to achieve wideband linear and power back-off (PBO) efficiency enhancement. Implemented in 65 nm bulk CMOS technology, this work realizes a measured 3 dB bandwidth of 15.5 GHz with 21.2 dB peak small-signal gain at 34.2 GHz. Under 1-V power supply, it achieves OP_1dB over 13.4 dBm and P_sat over 16 dBm between 21 to 30 GHz. The measured maximum P_sat, OP_1dB, peak/OP_1dB/6dB_PBO PAE results are 17.5, 14.7 dBm, and 28.2%/23.2%/13.2%. Without digital pre-distortion (DPD) and equalization, EVMs are lower than −25.2 dB for 200 MHz 64-QAM signals. Besides, this work achieves −33.35, −23.52, and −20 dB EVMs for 100 MHz 256-QAM, 600 MHz 64-QAM and 2 GHz 16-QAM signals at 27 GHz without DPD and equalization.
- Doherty PA,
- load modulation,
- broadband,
- transformer,
- linear enhancement,
- efficiency enhancement

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