Multi-band/multi-mode and efficient transmitter based on a Doherty Power Amplifier (original) (raw)
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A Novel 3-Way Dual-Band Doherty Power Amplifier for Enhanced Concurrent Operation
IEEE Transactions on Microwave Theory and Techniques, 2021
This article presents the architecture and design methodology for a new type of dual-band Doherty power amplifier (DB-DPA), referred to as 3-Way DB-DPA, which consists of a main amplifier for each band and an auxiliary amplifier handling both bands. The 3-Way DB-DPA improves the average drain efficiency in concurrent dual-band operation compared to the traditional 2-Way DB-DPA, by avoiding early clipping in the main amplifiers, while benefiting from load-pulling from the auxiliary power amplifier (PA). This improvement is verified in theory and simulation at the current-source reference planes and in measurement with a fabricated 1.5-and 2-GHz dualband PA. A statistical analysis using 2-D continuous-wave (CW) signals with long-term evolution (LTE) probability distribution functions (PDFs) is performed and demonstrated an improvement in the concurrent average efficiency by 15 percentage points compared to the conventional 2-Way DB-DPA. In nonconcurrent operation, the measured CW drain efficiency in the lower band (1.5 GHz) is 82.8% at peak and 66.6% at 9.6-dB backoff, and the measured CW drain efficiency in the upper band (2.0 GHz) is 70.0% at peak and 48.4% at 9.4-dB backoff. The CW concurrent-balanced drain efficiency reaches 66.2/52.0% in the 3-Way DB-DPA at 3-/6-dB backoff. In single-band operation at 1.5/2.0 GHz, the average power and average drain efficiency after linearization by digital predistortion (DPD) are 35.1/37.4 dBm and 65.0/53.7%, respectively, for an LTE signal with 10-MHz bandwidth and 6.1-dB peak-to-average power ratio (PAPR). In concurrent operation, the 3-Way DB-DPA is driven by two Manuscript
Linear Doherty Power Amplifier With an Enhanced Back-Off Efficiency Mode for Handset Applications
IEEE Transactions on Microwave Theory and Techniques, 2014
This paper presents a linear Doherty power amplifier (PA) with enhanced back-off efficiency mode for handset applications. For linear Doherty operation, we analyze the gain modulation as well as the cancellation of the third-order intermodulation distortion in order to improve the linearity. A compact design method is also discussed to implement on a single chip for a handset. The proposed Doherty PA delivers good performance with regard to the third-generation (3G)/fourth-generation (4G) modulation signals. A switched-load power-mode PA is adopted in the proposed Doherty PA to enhance the efficiency in the lowpower region with over 10-dB back-off. For demonstration purposes, the PA is implemented using an InGaP/GaAs heterojunction bipolar transistor and AlGaAs/InGaAs pseudomorphic high electron-mobility transistor process. The PA is tested at 1.85 GHz using both a long-term evolution signal with 16-quadrature amplitude modulation, 7.5-dB peak-to-average power ratio, and 10-MHz bandwidth (BW) and a wideband code division multiple access signal with 3.3-dB PAPR and 3.84-MHz BW. The proposed linear Doherty PA with an enhanced back-off efficiency mode delivers good performance in both the high-and low-power modes, implying that the dual-power-mode Doherty PA configuration can be a promising candidate for extending the battery life of handheld devices in 3G and 4G wireless communication systems. Index Terms-Cancellation, Doherty, gain modulation, handset, heterojunction bipolar transistor (HBT), high-power mode (HPM), long-term evolution (LTE), low-power mode (LPM), power amplifier (PA), switched capacitor. I. INTRODUCTION P OWER amplifier modules (PAMs) for multi-mode multi-band (MMMB) operation have become an important research area because they enable worldwide global roaming for mobile smart phones. A converged linear power amplifier (PA) architecture was proposed and developed to reduce the number of PA paths in an MMMB PAM.
Design of a Concurrent Dual-Band 1.8–2.4GHz GaN-HEMT Doherty Power Amplifier
IEEE Transactions on Microwave Theory and Techniques, 2012
In this paper, the design, implementation, and experimental results of a high-efficiency dual-band GaN-HEMT Doherty power amplifier (DPA) are presented. An extensive discussion about the design of the passive structures is presented showing different possible topologies of the dual-band DPA. One of the proposed topologies is used to design a dual-band DPA in hybrid technology for the frequency bands 1.8 and 2.4 GHz with the second efficiency peak at 6-dB output power back-off (OBO). For a continuous-wave output power of 20 W, the measured power-added efficiency (PAE) is 64% and 54% at 1.8 and 2.4 GHz, respectively. At -dB OBO, the resulting measured PAEs were 60% and 44% in the two frequency bands. Linearized concurrent modulated measurement using 10-MHz LTE signal with 7-dB peak-to-average-ratio (PAR) at 1.8 GHz and 10-MHz WiMAX signal with 8.5-dB PAR at 2.4 GHz shows an average PAE of 34%, at an adjacent channel leakage ratio of -48 dBc and -46 dBc at 1.8 and 2.4 GHz, respectively.
Toward a More Generalized Doherty Power Amplifier Design for Broadband Operation
IEEE Transactions on Microwave Theory and Techniques, 2016
The conventional Doherty power amplifier (DPA) theory is limited to single carrier operations, leading to a nongeneric structure. This paper presents a new analysis that generalizes the conventional DPA theory for increased efficiency and bandwidth. We demonstrate that by introducing a theoretical parameter ߙ at the output combiner we can redefine the relationships among the output combiner elements for a greater level of design flexibility than it was possible in the conventional DPA. We also show that previously published works in this area can be considered as special cases of the proposed general theory. As a demonstrator, a specific design, named Reduced-ࢻ Doherty power amplifier, realized using GaN HEMTs is provided to illustrate the robustness of the approach. This design proves effective for further improving the performance of the previously published 2.14/2.655 GHz dual-band parallel DPA. A maximum drain efficiency of 84% and 67% at an average of 43-dBm peak and 6-dB back-off power levels, respectively, were measured with continuous wave signals. To quantify the linearity performance, the proposed DPA was tested using wideband CDMA and longterm evolution (LTE) signals where the adjacent channel leakage ratio was recorded at-25 dBc with an average output power of 38.7 and 36.5 dBm at 2.14 and 2.655 GHz, respectively.
IEEE Transactions on Microwave Theory and Techniques, 2000
This paper proposes a new method for extending the bandwidth of Doherty power amplifiers (PAs) in the digital domain. The bandwidth enhancement is achieved through a frequency-selective pre-compensation mechanism that is derived to prevent the efficiency degradation that naturally occurs as the frequency of operation deviates from the center frequency. A methodical analysis of the frequency response of the conventional Doherty PA and that of the proposed Doherty PA is carried out to point out the limitations of the former and demonstrate the capability of the latter in recovering the bandwidth. Over the frequency range spanning from 1.96 to 2.46 GHz, the measured drain efficiency at 6-7-dB output power back-off is higher than 40% for the proposed Doherty PA. Such efficiency performance is achievable only from 2.04 to 2.22 GHz using the conventional Doherty PA. Hence, the bandwidth is enhanced from 180 to 500 MHz, which corresponds to an increase by a factor of 2.8 (i.e., almost triple). By applying the proposed methodology, a Doherty PA that is originally designed at the center frequency of 2.14 GHz for downlink wideband code division multiple access became operative at 1.98-GHz uplink wideband code division multiple access (UL-WCDMA), 2.22-GHz long-term evolution (LTE), and 2.34-GHz worldwide interoperability for microwave access (WiMAX) bands. The average drain efficiencies for UL-WCDMA, LTE, and WiMAX applications, were 40.1%, 44.2%, and 41.4%, respectively, using the proposed Doherty PA, and 37%, 37.3%, and 35.2%, respectively, using the conventional Doherty PA.
A Novel Two-Stage Broadband Doherty Power Amplifier for Wireless Applications
IEEE Microwave and Wireless Components Letters, 2018
Broadband and highly efficient amplifiers are of great interest in modern wireless communication systems. In this paper, we present a novel two-stage broadband Doherty power amplifier (DPA), which is able to maintain high efficiency at saturated output power and at backoff output power levels over a wide bandwidth. The amplifier uses a novel and simple approach to achieve bandwidth enhancement and at the same time uses a driver amplifier. We employ Klopfenstein taper to deliver wide bandwidth. The measurement results show that the proposed broadband two-stage DPA is able to deliver 31%-35% drain efficiency at 6-dB output power backoff while at the saturation it achieves 40%-55% drain efficiency over the designed bandwidth of 1.5 to 2.6 GHz. The amplifier can deliver above 35-dBm output power with substantial gain of around 20 dB. The proposed DPA is a promising candidate for wideband and high gain requirements in modern wireless systems.
Accelerated Design Methodology for Dual-Input Doherty Power Amplifiers
IEEE Transactions on Microwave Theory and Techniques
A novel design theory and the methodology are presented for dual-input Doherty power amplifiers (DPAs) in which the auxiliary transistor does not fully turn off at backoff power. Given the input parameters selected by the PA designer, a Doherty load modulation behavior is exactly implemented at the current-source reference planes of the transistors by solving for the characteristic impedance of the Doherty quarter-wave transformer and the common load. The Doherty output combiner at the package reference plane that sustains the desired dual-input DPA performance is then synthesized using nonlinear embedding and exactly implemented with a lossless and reciprocal circuit. The new analytic DPA design theory also provides an expanded design space, which facilitates the selection of the optimal design based on the gain, linearity, and efficiency tradeoff. The design methodology is implemented in a software program to enable the automatic design of a dual-input DPA prototype at the package reference planes within 24 s. To validate the theory and the design methodology, a 2-GHz dual-input asymmetric DPA is fabricated and measured. When excited with a 20-MHz local thermal equilibrium (LTE) signal with 9.55-dB peak-toaverage power ratio (PAPR), the DPA achieves an average power-added efficiency (PAE) of 51.6% with an adjacent-channelpower-leakage ratio (ACLR) of −47.1 dBc after linearization.
Advanced Doherty power amplifier design for modern communication systems
2018
Mobile communication technologies are becoming increasingly sophisticated and have experienced rapid evolution over the last few decades, and this is especially true for the base station transmitter. In response to the ever increasing demand in communication traffic and data throughput, largely driven by video based social media platforms, both spectral and power efficient device and systems are needed to fulfil the requirements. In terms of energy consumption, the power amplifier is an important component, and although developing efficient technologies for handset equipment is important, it is the base station element of the communications system that poses the greater challenge, having to deal with many channels simultaneously, resulting in the need to linearly and efficiently amplify highly dynamic phase and amplitude modulated signals possessing very large peak-to-average power ratios, at high power levels. This unique set of challenges has led to continuous research to improve ...
A Survey on RF and Microwave Doherty Power Amplifier for Mobile Handset Applications
Electronics
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.
2005 European Microwave Conference, 2005
We have proposed advanced design methods of Doherty amplifier for high efficiency base station power amplifiers with wide bandwidth. First, we develop Doherty amplifier with uneven power drive which is provided more input power to the peaking cell than the carrier cell for full power operation and appropriate load modulation. Second, we optimize the matching circuits of the carrier and peaking cells individually to enhance the linearity and efficiency. Third, we optimize the bias circuit to solve an asymmetric ACLR(Adjacent Channel Leakage Ratio) characteristics for wideband signals such as WCDMA 4FA. The proposed design methods are applied to implement Doherty amplifier using a MRF5P21180. For a 2.14 GHz WCDMA 4FA signal, the amplifier is optimized at 25 W average output power. The drain efficiency and ACLR measured at the power are 33 % and -41 dBc, which represent about 1.3 % and 3 dB improvements, respectively, compared to the Doherty amplifier with even power drive. Additionally, the PEP of the amplifier is about 180 W, while that of the comparable Doherty amplifier is about 165 W. The difference of ACLR with the bias circuit optimization between lower and upper ACLR is reduced below 2 dB at whole average output power range.