A survey on RF and microwave doherty power amplifier for mobile handset applications

This survey addresses the cutting-edge load modulation microwave and radio frequency power amplifiers for next-generation wireless communication standards. The basic operational principle of the Doherty amplifier and its defective behavior that has been originated by transistor characteristics will be presented. Moreover, advance design architectures for enhancing the Doherty power amplifier’s performance in terms of higher efficiency and wider bandwidth characteristics, as well as the compact design techniques of Doherty amplifier that meets the requirements of legacy 5G handset applications, will be discussed.Agencia Estatal de Investigación | Ref. TEC2017-88242-C3-2-RFundação para a Ciência e a Tecnologia | Ref. UIDP/50008/201

Low-profile and closely spaced four-element mimo antenna for wireless body area networks

A compact four-element multiple-input multiple output (MIMO) antenna is proposed for medical applications operating at a 2.4 GHz ISM band. The proposed MIMO design occupies an overall volume of 26 mm × 26 mm × 0.8 mm. This antenna exhibits a good impedance matching at the operating frequency of the ISM band, whose performance attributes include: isolation around 25 dB, envelope correlation coefficient (ECC) less than 0.02, average channel capacity loss (CCL) less than 0.3 bits/s/Hz and diversity gain (DG) of around 10 dB. The average peak realized gain of the four-element MIMO antenna is 2.4 dBi with more than 77 % radiation efficiency at the frequency of interest (ISM 2.4 GHz). The compact volume and adequate bandwidth, as well as the good achieved gain, make this antenna a strong candidate for bio-medical wearable applications

Ultra-Compact mm-Wave Monolithic IC Doherty Power Amplifier for Mobile Handsets

This work develops a novel dynamic load modulation Power Amplifier (PA) circuity that can provide an optimum compromise between linearity and efficiency while covering multiple cellular frequency bands. Exploiting monolithic microwave integrated circuits (MMIC) technology, a fully integrated 1W Doherty PA architecture is proposed based on 0.1 μm AlGaAs/InGaAs Depletion-Mode (D-Mode) technology provided by the WIN Semiconductors foundry. The proposed wideband DPA incorporates the harmonic tuning Class-J mode of operation, which aims to engineer the voltage waveform via second harmonic capacitive load termination. Moreover, the applied post-matching technique not only reduces the impedance transformation ratio of the conventional DPA, but also restores its proper load modulation. The simulation results indicate that the monolithic drive load modulation PA at 4 V operation voltage delivers 44% PAE at the maximum output power of 30 dBm at the 1 dB compression point, and 34% power-added efficiency (PAE) at 6 dB power back-off (PBO). A power gain flatness of around 14 ± 0.5 dB was achieved over the frequency band of 23 GHz to 27 GHz. The compact MMIC load modulation technique developed for the 5G mobile handset occupies the die area of 3.2 mm2

Design of a wideband harmonically tuned Class-J Power Amplifier

This paper describes a modern design idea of wideband and high efficient GaN HEMT Class-J power amplifiers. The operation principle of the Class-J mode, based on the second harmonic tuning, is introduced which can maximize the achievable efficiency. Matching network synthesis criteria for wideband frequency response are addressed for 5G power amplifiers design. This wideband harmonically tuned technique is applicable to amplifiers based on adjusting the shape of the waveforms through a a finite number of harmonics, such as Class-F,F−1 and E. Simulation results indicate that Class-J can provide a high drain efficiency of 70% across a 1.5 to 3.2 GHz bandwidth while delivering 10W output power at the 1dB- compression point, using GaN technology.Agencia Estatal de Investigación | Ref. TEC2017-88242-C3-2-

A compelet design procedure of an X-band MMIC Class-J Power Amplifier

This work presents a complete design process of a high-gain MMIC Class-J power amplifier (PA) based on the 0.25−μm A1GaAs-InGaAs pHEMT technology at X-Band frequencies. The proposed technique can reduce the chip area and improve the energy efficiency. The simulation results indicate that the designed Class-J PA at 6V operation voltage achieves 18dB power gain, 56% PAE and output power of 27.6dBm at 1dB compression. The area size of two-stages PA is 0.9mm2 .Fundação para a Ciência e a Tecnologia | Ref. UIDB/50008/2020Fundação para a Ciência e a Tecnologia | Ref. UIDP/50008/2020Fundação para a Ciência e a Tecnologia | Ref. POCI-01-0145-FEDER-030500Fundação para a Ciência e a Tecnologia | Ref. ECSEL/0006/201

Energy efficient and wideband class-J doherty power amplifier

This paper presents a systematic design technique for a wideband GaN HEMT Class-J Doherty amplifier based on the second harmonic tuning. Following a theoretical explore on the expanded design space for a dynamic load modulation, the output matching networks of both Carrier and Peaking amplifiers are synthesized to satisfy the Class-J load requirement. A wideband Class J DPA with a symmetrical architecture is designed as a proof-of-concept to operate over a 1.5 to 3.2 GHz band frequency and delivers 40%-47% power added efficiency.Agencia Estatal de Investigación | Ref. TEC2017-88242-C3-2-

Compact Millimeter-Wave MIMO Antenna for 5G Applications

An efficient four-elements mmWave multiple-input multiple output (MIMO) antenna is proposed for use in 5G system The proposed MIMO mmWave design operates at 35GHz and occupies an overall volume of 12.5 mm × 12.5 mm × 0.8 mm 3 . This antenna exhibits a good matching impedance at the operating frequency of 35GHz mmWave band, where an isolation greater than 25 dB, envelope correlation coefficient (ECC) less than 0.02, and diversity gain (DG) of around 10dB are obtained. The 4-elements MIMO mmWave antenna also shows a peak gain of 6 dBi with 87% of peak radiation efficiency. The obtained results along with size miniaturization signify that the proposed MIMO antenna is deemed as an appropriate candidate for millimeter wave based wireless applications

Load‐modulation technique without using quarter‐wavelength transmission line

A proposed method for achieving active load-modulation technique without using a quarter-wavelength transmission line is discussed and evaluated. The theoretical analysis shows that the active load-modulation can be achieved without using a quarter-wavelength line, where the main amplifier sees a low impedance when the input signal level is low, and this impedance increases in proportion to the amount of current contributed from the peaking amplifier. The peaking amplifier sees an impedance decreasing from infinity to the normalized impedance. To validate the method, a circuit was designed, simulated and fabricated using two symmetrical gallium nitride (GaN) transistors (6 W) to achieve a peak power of 12 W and 6 dB output back-off efficiency. The design operates with 400 MHz bandwidth at 3.6 GHz and showed an average efficiency of 50% at 6 dB back-off and an efficiency of 75% at peak power. The designed circuit was tested with CW and modulated signals, the amplifier showed an Adjacent Channel Power Ratio (ACPR) of 31–35.5 dB when tested with a wideband code division multiple access signal of 6 dB peak-average-power ratio (PAPR) at 35.5 dBm average power. Additional 20 dB of linearity improvement was achieved after adding a lineariser