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Author = Zhu, Anding;
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Displaying Results 1 - 25 of 49 on page 1 of 2
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1-b Observation for Direct-Learning-Based Digital Predistortion of RF Power Amplifiers
(2017)
Wang, Haoyu; Li, Gang; Zhou, Chongbin; Zhu, Anding; et al.
1-b Observation for Direct-Learning-Based Digital Predistortion of RF Power Amplifiers
(2017)
Wang, Haoyu; Li, Gang; Zhou, Chongbin; Zhu, Anding; et al.
Abstract:
In this paper, we propose a low-cost data acquisition approach for model extraction of digital predistortion (DPD) of RF power amplifiers. The proposed approach utilizes only 1-bit resolution analog-to-digital converters (ADCs) in the observation path to digitize the error signal between the input and output signals. The DPD coefficients are then estimated based on the direct learning architecture using the measured signs of the error signal. The proposed solution is proved to be feasible in theory and the experimental results show that the proposed algorithm achieves equivalent performance as that using the conventional method. Replacing high resolution ADCs with 1- bit comparators in the feedback path can dramatically reduce the power consumption and cost of the DPD system. The 1-bit solution also makes DPD become practically implementable in future broadband systems since it is relatively straightforward to achieve an ultra-high sampling speed in data conversion by using only sim...
http://hdl.handle.net/10197/8381
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28/38 GHz Dual-band Dual-polarized Highly Isolated Antenna for 5G Phased Array Applications
(2019)
Chu, Chenhao; Zhu, Jianfeng; Liao, Shaowei; Zhu, Anding; Xue, Quan
28/38 GHz Dual-band Dual-polarized Highly Isolated Antenna for 5G Phased Array Applications
(2019)
Chu, Chenhao; Zhu, Jianfeng; Liao, Shaowei; Zhu, Anding; Xue, Quan
Abstract:
IEEE IWS 2019: Sixth IEEE MTT-S International Wireless Symposium, Guangzhou, China, 19-22 May 2019
This paper proposed a new dual-band dual-polarized array antenna operating at 28 GHz and 38 GHz for 5G communication applications. Three stacked patches are adopted to achieve the dual-band operation. The lower band from 27.48 to 28.50 GHz is achieved by using the lower large patch, which is couple-fed by the middle patch. While the upper band from 36.94 to 40.43 GHz is achieved by using the middle and upper patches. The two patches resonant at 38 and 40 GHz respectively and the two resonant modes coupled together, which greatly enhances the upper band. To increase the polarization isolation in the lower band, a shorting pin connecting the lower patch and ground is utilized. Taking advantages of the multi-layer technology, the position of the vertical feeding probe between the middle patch and lower patch is slightly shifted to ensure the good impedance matching in both lower band ...
http://hdl.handle.net/10197/11051
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A 1.8–2.3 GHz broadband Doherty power amplifier with a minimized impedance transformation ratio
(2019)
Yang, Mengsu; Xia, Jing; Zhu, Anding
A 1.8–2.3 GHz broadband Doherty power amplifier with a minimized impedance transformation ratio
(2019)
Yang, Mengsu; Xia, Jing; Zhu, Anding
Abstract:
The 2015 Asia-Pacific Microwave Conference (APMC), Nanjing, China, 6-9 December 2015
In this paper, the design and measurement results of a 1.8 GHz to 2.3 GHz broadband Doherty power amplifier (DPA) are reported. A modified load modulation network is designed to minimize impedance transformation ratio over the entire dynamic range for the purpose of extending the operating bandwidth. Experimental results show that the drain efficiency of the proposed DPA maintains above 50% and 63% with continuous wave input signal powers of 26 dBm and 34 dBm, respectively, from 1.8 GHz to 2.3 GHz. When stimulated by a 60-MHz, 12- carrier UMTS signal at 2.14 GHz, the proposed DPA achieved an average efficiency of 53% at 7.6 dB back-off, while the corresponding adjacent channel leakage ratio is linearized to -48.4 dBc with digital predistortion.
Science Foundation Ireland
China Scholarship Council
http://hdl.handle.net/10197/10243
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A 2.0–2.5 GHz frequency-selectable oscillator for digital predistortion model identification of RF power amplifiers
(2019)
McGrath, Kevin; Zhu, Anding
A 2.0–2.5 GHz frequency-selectable oscillator for digital predistortion model identification of RF power amplifiers
(2019)
McGrath, Kevin; Zhu, Anding
Abstract:
The 2017 Integrated Nonlinear Microwave and Millimetre-wave Circuits Workshop (INMMiC), Graz, Austria, 20-21 April 2017
This paper presents the design of a frequency selectable oscillator used as part of a new data acquisition architecture for digital predistortion (DPD) of RF power amplifiers (PAs). The proposed architecture aims to alleviate the requirement of high sampling rate analog-to-digital-converters (ADCs) in the data acquisition loop. The oscillator utilizes switchable capacitors with a digital control scheme and is capable of operating between 2.0 GHz and 2.5 GHz with an approximate frequency step size of 512 kHz.
European Commission - European Regional Development Fund
Science Foundation Ireland
http://hdl.handle.net/10197/10309
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A Broadband Continuous Class-FGaN MMIC PA Using Multi-Resonance Matching Network
(2020)
Nikandish, Gholamreza; Staszewski, Robert Bogdan; Zhu, Anding
A Broadband Continuous Class-FGaN MMIC PA Using Multi-Resonance Matching Network
(2020)
Nikandish, Gholamreza; Staszewski, Robert Bogdan; Zhu, Anding
Abstract:
The 49th European Microwave Conference, Paris, France, 29 September - 4 October 2019
In this paper, we present a design technique for broadband harmonic-tuned monolithic microwave integrated circuit (MMIC) power amplifiers (PAs). A multi-resonance harmonic matching network is proposed for the continuous class -F mode operation, featuring low loss and compact chip area for integrated PA realization. A design procedure is developed for this network, considering low quality factor and electromigration current density limitation of on-chip inductors. A proof-of-concept GaN MMIC PA, implemented in a 0.25-μ m GaN-on-SiC technology, provides 33. 9-36.ldBm output power and 38-48% power-added efficiency (PAE) in the frequency band 4-6GHz. For a 64-QAM signal with 100 MHz modulation bandwidth and 8 dB peak-to-average power ratio (PAPR), at 5 GHz, the average output power of 30.2 dBm and average PAE of 32% are achieved, while the error vector magnitude (EVM) is -32dB.
European Commissi...
http://hdl.handle.net/10197/11472
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A Broadband High-Efficiency Doherty Power Amplifier with Integrated Compensating Reactance
(2017)
Xia, Jing; Yang, Mengsu; Guo, Yan; Zhu, Anding
A Broadband High-Efficiency Doherty Power Amplifier with Integrated Compensating Reactance
(2017)
Xia, Jing; Yang, Mengsu; Guo, Yan; Zhu, Anding
Abstract:
This paper presents a high-efficiency gallium nitride Doherty power amplifier (DPA) using an integrated compensating reactance (CR) for broadband operation. With an additional quarter-wavelength transmission line integrated in the peaking amplifier output, a CR is generated to compensate the load impedance of the carrier amplifier in the low-power region and thus enhance the back-off efficiency over a wide frequency range without affecting the Doherty load modulation at saturation. For this purpose, a peaking output matching network (OMN) is employed to convert the output impedance of the peaking device into quasi-short circuit when it is off and achieve proper impedance matching when it is on. A two-point matching technique using the transmission (ABCD) matrix is employed to design such desired OMN. Measurement results show that the DPA has a 6-dB back-off efficiency of 50%-55% and a saturated efficiency of 57%-71% over the frequency band of 1.7-2.8 GHz (49% fractional bandwidth). ...
http://hdl.handle.net/10197/8390
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A channelized sideband distortion model for suppressing unwanted emission of Q-band millimeter wave transmitters
(2017)
Yu, Chao; Sun, Honglei; Zhu, Xiao-Wei; Zhu, Anding
A channelized sideband distortion model for suppressing unwanted emission of Q-band millimeter wave transmitters
(2017)
Yu, Chao; Sun, Honglei; Zhu, Xiao-Wei; Zhu, Anding
Abstract:
2016 IEEE MTT-S International Microwave Symposium (IMS), San Francisco, California, USA, 22-27 May 2016
In this paper, a channelized sideband distortion model is proposed to suppress the unwanted emission of Q-band millimeter wave (mmWave) transmitters in wideband contiguous carrier aggregation scenarios. By employing this model, the compensating bandwidth or center frequency can be agilely controlled. Experiments were conducted on a 40 GHz mmWave power amplifier to validate this idea. The satisfactory performance proved that the proposed model is a promising candidate for future 5G applications.
http://hdl.handle.net/10197/8642
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A Modified Decomposed Vector Rotation-Based Behavioral Model With Efficient Hardware Implementation for Digital Predistortion of RF Power Amplifiers
(2017)
Cao, Wenhui; Zhu, Anding
A Modified Decomposed Vector Rotation-Based Behavioral Model With Efficient Hardware Implementation for Digital Predistortion of RF Power Amplifiers
(2017)
Cao, Wenhui; Zhu, Anding
Abstract:
This paper proposes a novel hardware implementation strategy to achieve low-cost design for digital predistortion (DPD) of radio frequency (RF) power amplifiers (PAs) using a modified decomposed vector rotation (DVR)-based behavioral model. To make the model hardware friendly, we first modify the model into a sub-decomposed format which significantly reduces the computational complexity in model extraction. We then reassemble the coefficients and propose a simple digital implementation structure for real-time signal processing in the transmit path. A new Dual-Direction COordinate Rotation DIgital Computer (DD-CORDIC) design is also proposed to simultaneously calculate both magnitude and ejθn values to facilitate the model implementation. To validate hardware implementation, a wide-band signal is employed to evaluate the performance with a Doherty power amplifier. Experimental results show that the proposed approach can achieve comparable performance with much lower system complexity...
http://hdl.handle.net/10197/8380
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A reconfigurable in-band digital predistortion technique for mmWave power amplifiers excited by a signal with 640 MHz modulation bandwidth
(2019)
Yu, Chao; Hou, Debin; Sun, Honglei; Zhu, Anding; et al.
A reconfigurable in-band digital predistortion technique for mmWave power amplifiers excited by a signal with 640 MHz modulation bandwidth
(2019)
Yu, Chao; Hou, Debin; Sun, Honglei; Zhu, Anding; et al.
Abstract:
The 12th European Microwave Integrated Circuits Conference, Nuremberg, Germany, 8-10 October 2017
In this paper, a novel in-band digital predistortion (I-DPD) technique with a reconfigurable coefficient pyramid is proposed to linearize a mmWave power amplifier excited by a modulated signal with very large bandwidth, such as 640 MHz. This method can overcome the multiple bandwidth regrowth issue in conventional DPD operation that normally places a burden on the 5G applications. By employing a coefficient pyramid, the proposed method can efficiently select the necessary core functions to build the nonlinear kernels according to the operation modes, which can largely reduce the power consumption and thus increase the system efficiency. Experimental results with 640MHz modulated signal proves that extending the DPD capability into the forthcoming 5G is possible.
National Natural Science Foundation of China (NSFC)
Natural Science Foundation of Jiangsu Province
http://hdl.handle.net/10197/10329
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A Single Envelope Modulator-Based Envelope-Tracking Structure for Multiple-Input and Multiple-Output Wireless Transmitters
(2017)
Yu, Chao; Zhu, Anding
A Single Envelope Modulator-Based Envelope-Tracking Structure for Multiple-Input and Multiple-Output Wireless Transmitters
(2017)
Yu, Chao; Zhu, Anding
Abstract:
A single envelope modulator-based envelope tracking (ET) power amplifier (PA) structure with a related digital predistortion (DPD) technique for multiple-input and multiple-output (MIMO) wireless transmitters is presented in this paper. By generating a common tracking envelope, only one envelope modulator is employed for controlling supply voltage of the RF PAs in all branches in the system, which dramatically reduces the system implementation cost. Due to the structurechange, additional distortion is introduced, and it is difficult to directly compensate by using the conventional DPD because the tracking envelope is no longer the same as the RF envelope and thus the MIMO ET PA becomes a two-input and one-output system. To resolve this problem, in this paper we propose a novel DPD technique in which the PA input and output data are reconstructed into multiple data subsets according to variations of the tracking envelope. It converts the 2-to-1 mapping into multiple 1-to-1 ones, wher...
http://hdl.handle.net/10197/8644
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Analysis and Design of Highly Efficient Wideband RF-Input Sequential Load Modulated Balanced Power Amplifier
(2020)
Pang, Jingzhou; Li, Yue; Li, Meng; Zhang, Yikang; Zhou, Xin Yu; Dai, Zhijiang; Zhu, Anding
Analysis and Design of Highly Efficient Wideband RF-Input Sequential Load Modulated Balanced Power Amplifier
(2020)
Pang, Jingzhou; Li, Yue; Li, Meng; Zhang, Yikang; Zhou, Xin Yu; Dai, Zhijiang; Zhu, Anding
Abstract:
The analysis and design of an RF-input sequential load modulated balanced power amplifier (SLMBA) are presented in this article. Unlike the existing LMBAs, in this new configuration, an over-driven class-B amplifier is used as the carrier amplifier while the balanced PA pair is biased in class-C mode to serve as the peaking amplifier. It is illustrated that the sequential operation greatly extends the high-efficiency power range and enables the proposed SLMBA to achieve high back-off efficiency across a wide bandwidth. An RF-input SLMBA at 3.05-3.55-GHz band using commercial GaN transistors is designed and implemented to validate the proposed architecture. The fabricated SLMBA attains a measured 9.5-10.3-dB gain and 42.3-43.7-dBm saturated power. Drain efficiency of 50.9-64.9/ 46.8-60.7/43.2-51.4% is achieved at 6-/8-/10-dB output power back-off within the designed bandwidth. By changing the bias condition of the carrier device, higher than 49.1% drain efficiency can be obtained wit...
http://hdl.handle.net/10197/11748
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Band-Limited Volterra Series-Based Digital Predistortion for Wideband RF Power Amplifiers
(2017)
Yu, Chao; Guan, Lei; Zhu, Erni; Zhu, Anding
Band-Limited Volterra Series-Based Digital Predistortion for Wideband RF Power Amplifiers
(2017)
Yu, Chao; Guan, Lei; Zhu, Erni; Zhu, Anding
Abstract:
The continuously increasing demand for wide bandwidth creates great difficulties in employing digital predistortion (DPD) for radio frequency (RF) power amplifiers (PAs) in future ultra-wideband systems because the existing DPD system requires multiple times the input signal bandwidth in the transmitter and receiver chain, which is sometimes almost impossible to implement in practice. In this paper, we present a novel band-limited digital predistortion technique in which a band-limiting function is inserted into the general Volterra operators in the DPD model to control the signal bandwidth under modeling, which logically transforms the general Volterra series-based model into a band-limited version. This new approach eliminates the system bandwidth constraints of the conventional DPD techniques, and it allows users to arbitrarily choose the bandwidth to be linearized in the PA output according to the system requirement without sacrificing performance, which makes the DPD system des...
http://hdl.handle.net/10197/8643
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Bandwidth Enhancement of Doherty Power Amplifier Using Modified Load Modulation Network
(2020)
Li, Meng; Pang, Jingzhou; Li, Yue; Zhu, Anding
Bandwidth Enhancement of Doherty Power Amplifier Using Modified Load Modulation Network
(2020)
Li, Meng; Pang, Jingzhou; Li, Yue; Zhu, Anding
Abstract:
A novel Doherty power amplifier (DPA) architecture with extended bandwidth is presented in this paper. A modified load modulation network is introduced to provide impedance condition required by the Doherty operation in a wide frequency range. Analytical parameter solutions of the proposed load modulation network and the related load modulation process are presented. A DPA with 2.80-3.55 GHz bandwidth utilizing commercial GaN transistors is implemented. The fabricated DPA attains a measured 9.3-11.1 gain and 43.0-45.0 dBm saturated power. 50.0-60.6% and 66-78% drain efficiency is obtained at 6 dB output power back-off and saturation throughout the designed band, respectively. Moreover, the back-off drain efficiencies are higher than 55% within 700 MHz bandwidth. When driven by a 6-carrier 120 MHz OFDM signal with 7.0 dB peak to average power ratio, the proposed DPA achieves adjacent channel leakage ratio of better than -50 dBc after digital pre-distortion (DPD) at 3.20 GHz with aver...
http://hdl.handle.net/10197/11746
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Behavioral modeling for digital predistortion of RF power amplifiers: from Volterra series to CPWL functions
(2019)
Zhu, Anding
Behavioral modeling for digital predistortion of RF power amplifiers: from Volterra series to CPWL functions
(2019)
Zhu, Anding
Abstract:
The 2016 IEEE Topical Conference on Power Amplifiers for Wireless and Radio Applications ( PAWR), Austin, Texas, United States of America, 24-27 January 2016
This paper gives an overview of behavioral modeling for digital predistortion of RF power amplifiers. It starts with discussing the specific system requirements and then explains what constraints must be satisfied when developing behavioral models for this application. Both theoretical aspects and practical implementation issues are discussed. Historical development and recent innovation are reviewed with a conclusion of future outlook in the end.
European Commission - European Regional Development Fund
Science Foundation Ireland
http://hdl.handle.net/10197/10242
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Broadband Fully Integrated GaN Power Amplifier With Embedded Minimum Inductor Bandpass Filter and AM-PM Compensation
(2019)
Nikandish, Gholamreza; Staszewski, Robert Bogdan; Zhu, Anding
Broadband Fully Integrated GaN Power Amplifier With Embedded Minimum Inductor Bandpass Filter and AM-PM Compensation
(2019)
Nikandish, Gholamreza; Staszewski, Robert Bogdan; Zhu, Anding
Abstract:
In this paper, we present a design technique for broadband linearized fully integrated GaN power amplifiers (PAs). The minimum inductor bandpass filter structure is used as the output matching network to achieve low loss and high out-of-band attenuation. Two parallel transistors with unbalanced gate biases are used to mitigate nonlinearity of their transconductance and input capacitance, and consequently, compensate AM-PM distortion of the PA. A fully integrated GaN PA prototype provides 35.1–38.9 dBm output power and 40-55% power-added efficiency (PAE) in 2.0–4.0 GHz. For a 64-QAM signal with 8-dB peak-to-average power ratio (PAPR) and 100-MHz bandwidth at 2.4 GHz, average output power of 32.7 dBm and average PAE of 31% are measured with −30.2 dB error vector magnitude (EVM).
Science Foundation Ireland
Trinity College Dublin (TCD)
http://hdl.handle.net/10197/10907
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Decomposed Vector Rotation-Based Behavioral Modeling for Digital Predistortion of RF Power Amplifiers
(2017)
Zhu, Anding
Decomposed Vector Rotation-Based Behavioral Modeling for Digital Predistortion of RF Power Amplifiers
(2017)
Zhu, Anding
Abstract:
A new behavioral model for digital predistortion of radio frequency (RF) power amplifiers (PAs) is proposed in this paper. It is derived from a modified form of the canonical piecewise-linear (CPWL) functions using a decomposed vector rotation (DVR) technique. In this model, the nonlinear basis function is constructed from piecewise vector decomposition, which is completely different from that used in the conventional Volterra series. Theoretical analysis has shown that this model is much more flexible in modeling RF PAs with non-Volterra-like behavior, and experimental results confirmed that the new model can produce excellent performance with a relatively small number of coefficients when compared to conventional models.
Science Foundation Ireland
http://hdl.handle.net/10197/8424
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Design Considerations of the Interpolative Digital Transmitter for Quantization Noise and Replicas Rejection
(2019)
Un, Ka-Fai; Zhang, Feifei; Mak, Pui-In; Martins, Rui P.; Zhu, Anding; Staszewski, Rober...
Design Considerations of the Interpolative Digital Transmitter for Quantization Noise and Replicas Rejection
(2019)
Un, Ka-Fai; Zhang, Feifei; Mak, Pui-In; Martins, Rui P.; Zhu, Anding; Staszewski, Robert Bogdan
Abstract:
Digital transmitter (DTX) offers the desired signal efficiency and flexibility than its analog counterpart by merging signal amplification and modulation. Yet, the high-speed digital baseband interface is challenging and bulky for achieving low out-of-band noise. This Brief is an analytical study of the DTX linear interpolation technique, which can be adapted easily for optimizing the replica rejection and noise-filtering capabilities of the DTX.
Microelectronic Circuits Centre Ireland
Macau FDCT – SKL Fund
University of Macau
http://hdl.handle.net/10197/10908
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Digital Compensation for Transmitter Leakage in Non-Contiguous Carrier Aggregation Applications With FPGA Implementation
(2017)
Yu, Chao; Cao, Wenhui; Guo, Yan; Zhu, Anding
Digital Compensation for Transmitter Leakage in Non-Contiguous Carrier Aggregation Applications With FPGA Implementation
(2017)
Yu, Chao; Cao, Wenhui; Guo, Yan; Zhu, Anding
Abstract:
In this paper, a generalized dual-basis envelope-dependent sideband (GDES) distortion model structure is proposed to compensate the distortion induced by transmitter leakage in concurrent multi-band transceivers with non-contiguous carrier aggregation. This model has a generalized structure that is constructed via first generating a nonlinear basis function that maps the inputs to the target frequency band where the distortion is to be cancelled, and then multiplying with a second basis function that generates envelope-dependent nonlinearities. By combining these two bases, the model keeps in a relatively compact form that can be flexibly implemented in digital circuits such as field programmable gate array (FPGA). Experimental results demonstrated that excellent suppression performance can be achieved with very low implementation complexity by employing the proposed model.
Science Foundation Ireland
http://hdl.handle.net/10197/8407
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Digital linear pre-compensation technique to enhance predistortion performance in multicarrier DVB-S2 satellite communication systems
(2017)
Allegue-Martínez, Michel; Kelly, Noel; Zhu, Anding
Digital linear pre-compensation technique to enhance predistortion performance in multicarrier DVB-S2 satellite communication systems
(2017)
Allegue-Martínez, Michel; Kelly, Noel; Zhu, Anding
Abstract:
Nonlinearity in communication satellite payloads often severely degrades the downlink signal quality in such systems. A digital precompensation technique to enhance digital predistortion performance in multicarrier satellite communication systems is presented. The proposed technique has been validated by simulations with an appropriate platform where excellent performance improvements have been measured. In addition, the implementation feasibility of this technique has been briefly demonstrated by means of a real-time FPGA implementation.
European Space Agency (ESA)
http://hdl.handle.net/10197/8655
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Digital Suppression of Transmitter Leakage in FDD RF Transceivers With an Enhanced Low-Sampling Rate Behavioral Model
(2019)
Cao, Wenhui; Li, Yue; Luo, Guo Qing; Hao, Zhang Cheng; Zhu, Anding
Digital Suppression of Transmitter Leakage in FDD RF Transceivers With an Enhanced Low-Sampling Rate Behavioral Model
(2019)
Cao, Wenhui; Li, Yue; Luo, Guo Qing; Hao, Zhang Cheng; Zhu, Anding
Abstract:
With continuously increasing of signal bandwidth, the transmitter leakage issue in frequency division duplexer (FDD) transceivers becomes severer. In this letter, an enhanced behavioral model is proposed to suppress FDD transmitter leakage at a low-sampling rate. The theoretical analysis is provided to explain the operation principle of the proposed model. The experimental results show that the proposed model can effectively increase the accuracy of generating sideband replica and thus improve the suppression performance.
Science Foundation Ireland
Natural Science Foundation of China
http://hdl.handle.net/10197/10637
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Digital Suppression of Transmitter Leakage in FDD RF Transceivers: Aliasing Elimination and Model Selection
(2019)
Cao, Wenhui; Li, Yue; Zhu, Anding
Digital Suppression of Transmitter Leakage in FDD RF Transceivers: Aliasing Elimination and Model Selection
(2019)
Cao, Wenhui; Li, Yue; Zhu, Anding
Abstract:
The transmitter (TX)-induced interference due to power amplifier nonlinearities poses severe desensitization problems to the receiver chain in frequency-division duplexing transceivers. Due to nonlinear signal process involved, a high sampling rate is normally required in the existing digital suppression approaches, which can result in high cost and high power consumption in wideband systems. In this paper, a new digital suppression model is proposed to cancel the TX leakage at baseband with a low sampling rate. The cancellation model is based on the modified decomposed vector rotation model. With the addition of cross-Term products, the enhanced model is capable of eliminating the aliasing effect arising from the reduced sampling rate. Theoretical analysis of aliasing elimination is presented, and the algorithm is subsequently verified by both simulation and experiment results, confirming the effectiveness and feasibility of the proposed cancellation technique for TX leakage suppre...
http://hdl.handle.net/10197/10381
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Digitally-Assisted Dual-Switch High Efficiency Envelope Amplifier for Envelope Tracking Base-Station Power Amplifiers
(2017)
Hsia, Chin; Zhu, Anding; Yan, Jonmei J.; et al.
Digitally-Assisted Dual-Switch High Efficiency Envelope Amplifier for Envelope Tracking Base-Station Power Amplifiers
(2017)
Hsia, Chin; Zhu, Anding; Yan, Jonmei J.; et al.
Abstract:
This paper presents a novel digitally assisted dual-switch envelope amplifier used for wideband high-efficiency envelope-tracking (ET) base-station power amplifiers (PAs). The proposed envelope amplifier comprises two switching buck converters to provide the high-power ET signal to the RF stage and a wideband linear stage to maintain the envelope signal accuracy. The control technique utilizes digital signal processing in conjunction with analog hysteretic feedback to separately control two high-efficiency switchers and thus successfully reduces power consumption of the linear stage, especially for applications requiring high peak-to-average ratio (PAPR) signals. The overall ET system was demonstrated using GaAs high-voltage HBT PAs. For a variety of signals ranging from 6.6- to 9.6-dB PAPR and up to 10-MHz RF bandwidth, the overall system power-added efficiency reached 50%-60%, with a normalized root-mean-square error below 1% and the first adjacent channel leakage power ratio of -...
http://hdl.handle.net/10197/8657
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Dual-loop Model Extraction for Digital Predistortion of Wideband RF Power Amplifiers
(2017)
Guan, Lei; Zhu, Anding
Dual-loop Model Extraction for Digital Predistortion of Wideband RF Power Amplifiers
(2017)
Guan, Lei; Zhu, Anding
Abstract:
A dual-loop parameter characterization structure is proposed in order to improve the accuracy of the model extraction in digital predistortion systems. In this concept, a model reference loop is used in conjunction with a model inverse structure for fine tuning the model parameters. This model extraction process does not increase much of the complexity of system implementation but experimental results show that linearization performance can be significantly improved by employing the proposed structure for wideband RF power amplifiers.
Science Foundation Ireland
http://hdl.handle.net/10197/8647
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Forward modeling assisted 1-Bit data acquisition based model extraction for digital predistortion of RF power amplifiers
(2017)
Wang, Haoyu; Li, Gang; Zhang, Yikang; Liu, Falin; Zhu, Anding
Forward modeling assisted 1-Bit data acquisition based model extraction for digital predistortion of RF power amplifiers
(2017)
Wang, Haoyu; Li, Gang; Zhang, Yikang; Liu, Falin; Zhu, Anding
Abstract:
2017 IEEE Topical Conference on RF/microwave Power Amplifiers for Radio and Wireless Applications (PAWR), Phoenix, Arizonia, USA, 15-18 January 2017
In this paper, a low-cost data acquisition approach with novel forward modeling is proposed for model extraction of digital predistortion (DPD) of RF power amplifiers (PA). Compared to the existing 1-bit DPD solution, the proposed approach employs a new loss function using only 1-bit resolution error signal to extract the forward model and the coefficients of DPD model can be extracted afterwards based on the estimated PA output. The proposed solution avoids the calculation of step size in the existing approach, and the convergence is guaranteed due to the convexity of the loss function. The experimental results show that the proposed algorithm achieves equivalent linearization performance as that using the conventional method.
Science Foundation Ireland
http://hdl.handle.net/10197/8492
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Gaussian Pulse-Based Two-Threshold Parallel Scaling Tone Reservation for PAPR Reduction of OFDM Signals
(2017)
Guan, Lei; Zhu, Anding
Gaussian Pulse-Based Two-Threshold Parallel Scaling Tone Reservation for PAPR Reduction of OFDM Signals
(2017)
Guan, Lei; Zhu, Anding
Abstract:
Tone Reservation (TR) is a technique proposed to combat the high Peak-to-Average Power Ratio (PAPR) problem of Orthogonal Frequency Division Multiplexing (OFDM) signals. However conventional TR suffers from high computational cost due to the difficulties in finding an effective cancellation signal in the time domain by using only a few tones in the frequency domain. It also suffers from a high cost of hardware implementation and long handling time delay issues due to the need to conduct multiple iterations to cancel multiple high signal peaks. In this paper, we propose an efficient approach, called two-threshold parallel scaling, for implementing a previously proposed Gaussian pulse-based Tone Reservation algorithm. Compared to conventional approaches, this technique significantly reduces the hardware implementation complexity and cost, while also reducing signal processing time delay by using just two iterations. Experimental results show that the proposed technique can effectively...
http://hdl.handle.net/10197/8491
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