This paper proposes a concurrent neural network model to mitigate non-linear distortion in power amplifiers using a basis function generation approach.The model is designed using polynomial expansion and comprises a f...This paper proposes a concurrent neural network model to mitigate non-linear distortion in power amplifiers using a basis function generation approach.The model is designed using polynomial expansion and comprises a feedforward neural network(FNN)and a convolutional neural network(CNN).The proposed model takes the basic elements that form the bases as input,defined by the generalized memory polynomial(GMP)and dynamic deviation reduction(DDR)models.The FNN generates the basis function and its output represents the basis values,while the CNN generates weights for the corresponding bases.Through the concurrent training of FNN and CNN,the hidden layer coefficients are updated,and the complex multiplication of their outputs yields the trained in-phase/quadrature(I/Q)signals.The proposed model was trained and tested using 300 MHz and 400 MHz broadband data in an orthogonal frequency division multiplexing(OFDM)communication system.The results show that the model achieves an adjacent channel power ratio(ACPR)of less than-48 d B within a 100 MHz integral bandwidth for both the training and test datasets.展开更多
正交时频空(Orthogonal Time Frequency Space,OTFS)调制因其在高速移动场景下优越的抗多普勒频移特性,被视为未来低地球轨道(Low Earth Orbit,LEO)卫星通信的关键候选技术。然而,OTFS信号固有的峰均功率比(Peak-to-Average Power Ratio...正交时频空(Orthogonal Time Frequency Space,OTFS)调制因其在高速移动场景下优越的抗多普勒频移特性,被视为未来低地球轨道(Low Earth Orbit,LEO)卫星通信的关键候选技术。然而,OTFS信号固有的峰均功率比(Peak-to-Average Power Ratio,PAPR)问题,会严重降低卫星高功率放大器(High-Power Amplifier,HPA)的效率,并引入显著的非线性失真,从而恶化误码率(Bit Error Rate,BER)性能。为解决此问题,提出了一种创新的混合自适应削波(Hybrid Adaptive Clipping,HAC)与神经网络预失真(Neural Network Predistortion)的方法——HAC-NNP。自适应削波(Adaptive Clipping,AC)模块根据实时信道质量或业务需求动态调整削波门限,在PAPR抑制和信号原始失真之间取得初步平衡;轻量级的神经网络(Neural Network,NN)预失真器在发射端对削波后的信号进行处理,训练后用于补偿由“削波处理”和“卫星HPA非线性效应”共同引入的复杂失真。仿真结果表明,在典型的LEO卫星信道和HPA非线性模型下,与传统削波方法相比,该HAC-NNP方法在将PAPR降低约3.5 dB的同时,能够显著改善由削波和HPA非线性共同导致的信号失真,将BER性能恢复至接近无HPA非线性影响的理想水平。展开更多
RF power amplifiers (PAs) are usually considered as memoryless devices in most existing predistortion techniques. Nevertheless, in wideband communication systems, PA memory effects can no longer be ignored and memoryl...RF power amplifiers (PAs) are usually considered as memoryless devices in most existing predistortion techniques. Nevertheless, in wideband communication systems, PA memory effects can no longer be ignored and memoryless predistortion cannot linearize PAs effectively. After analyzing PA memory effects, a novel predistortion method based on wavelet networks (WNs) is proposed to linearize wideband RF power amplifiers. A complex wavelet network with tapped delay lines is applied to construct the predistorter and then a complex backpropagation algorithm is developed to train the predistorter parameters. The simulation results show that compared with the previously published feed-forward neural network predistortion method, the proposed method provides faster convergence rate and better performance in reducing out-of-band spectral regrowth.展开更多
A digital predistorted class-F power amplifier （PA） using Cree GaN HEMT CGH40010 operating at 2. 12 GHz is presented to obtain high efficiency and excellent linearity for wideband code-division multiple access （ WC...A digital predistorted class-F power amplifier （PA） using Cree GaN HEMT CGH40010 operating at 2. 12 GHz is presented to obtain high efficiency and excellent linearity for wideband code-division multiple access （ WCDMA ） applications. Measurement results with the continuous wave （CW） signals indicate that the designed class-F PA achieves a peak power-added efficiency （PAE） of 75. 2% with an output power of 39.4 dBm. The adjacent channel power ratio （ACPR） of the designed PA after digital predistortion （DPD） decreases from -28. 3 and -27. 5 dBc to -51.9 and -54. 0 dBc, respectively, for a 4-carrier 20 MHz WCDMA signal with 7. 1 dB peak to average power ratio （PAPR）. The drain efficiency （DE） of the PA is 37. 8% at an average output power of 33. 3 dBm. The designed power amplifier can be aoolied in the WCDMA system.展开更多
To compensate for nonlinear distortion introduced by RF power amplifiers （PAs） with memory effects, two correlated models, namely an extended memory polynomial （EMP） model and a memory lookup table （LUT） model, ...To compensate for nonlinear distortion introduced by RF power amplifiers （PAs） with memory effects, two correlated models, namely an extended memory polynomial （EMP） model and a memory lookup table （LUT） model, are proposed for predistorter design. Two adaptive digital predistortion （ADPD） schemes with indirect learning architecture are presented. One adopts the EMP model and the recursive least square （RLS） algorithm, and the other utilizes the memory LUT model and the least mean square （LMS） algorithm. Simulation results demonstrate that the EMP-based ADPD yields the best linearization performance in terms of suppressing spectral regrowth. It is also shown that the ADPD based on memory LUT makes optimum tradeoff between performance and computational complexity.展开更多
This paper presents a dual-nonlinear branch linearizer for reducing the corrected amplitude overshoot of conventional single nonlinear branch linearizer. Theoretical analysis is carried out, the analysis is verified b...This paper presents a dual-nonlinear branch linearizer for reducing the corrected amplitude overshoot of conventional single nonlinear branch linearizer. Theoretical analysis is carried out, the analysis is verified by simulation, and a prototype of Ka band 25.28~26.08 GHz dual nonlinear branch linearizer is achieved. It indicates that the corrected amplitude overshoot is less than 0.5 dB, the C/I3 improvement is more than 10 dB related to a single carrier IBO 9 dB, when it is linked and tested for 50 W spacebrone Travelling Wave Tube Amplifier(TWTA).展开更多
A robust digital predistortion(DPD)technique utilizing negative feedback iteration is introduced for linearizing power amplifiers(PAs)in long term evolution(LTE)/5G systems.Different from the conventional direct learn...A robust digital predistortion(DPD)technique utilizing negative feedback iteration is introduced for linearizing power amplifiers(PAs)in long term evolution(LTE)/5G systems.Different from the conventional direct learning and indirect learning structure,the proposed DPD suggests a two-step method to identify the predistortion.Firstly,a negative feedback based iteration is used to estimate the optimal DPD signal.Then the corresponding DPD parameters are extracted by forward modeling with the input signal and optimal DPD signal.The iteration can be applied to both single-band and dual-band PAs,which will achieve superior linear performance than the conventional direct learning DPD while having a relatively low computational complexity.The measurement is carried out on a broadband Doherty PA(DPA)with a 200 MHz bandwidth LTE signal at 2.1 GHz,and on a 5G DPA with two 10 MHz LTE signals at 3.4/3.6 GHz for validation in dual-band scenarios.展开更多
Digital PreDistortion(DPD)is a very useful method to improve the linearity of Power Amplifiers(PAs)for LTE and upcoming 5 G networks.As the spectrum resources are becoming more and more crowded,and the communications ...Digital PreDistortion(DPD)is a very useful method to improve the linearity of Power Amplifiers(PAs)for LTE and upcoming 5 G networks.As the spectrum resources are becoming more and more crowded,and the communications bandwidth are broader,the ACPR(Adjacent Channel Leakage Ratio)is very important to communication systems.DPD is one of the useful means for PA to reduce ACPR.This article demonstrates what DPD is and how DPD is achieved,the measurement of the Digital Distortion of a PA using a vector generator and vector analyzer,and the measurement results has been discussed.展开更多
RF power amplifiers （PAs） are usually considered as memoryless devices in most existing predistortion techniques. However, in broadband communication systems, such as WCDMA, the PA memory effects are significant, an...RF power amplifiers （PAs） are usually considered as memoryless devices in most existing predistortion techniques. However, in broadband communication systems, such as WCDMA, the PA memory effects are significant, and memoryless predistortion cannot linearize the PAs effectively. After analyzing the PA memory effects, a novel predistortion method based on the simplified Volterra series is proposed to linearize broadband RF PAs with memory effects. The indirect learning architecture is adopted to design the predistortion scheme and the reeursive least squares algorithm with forgetting factor is applied to identify the parameters of the predistorter. Simulation results show that the proposed predistortion method can compensate the nonlinear distortion and memory effects of broadband RF PAs effectively.展开更多
At present what are the key points focused in the research of loop-delay estimation for the digital predistorter in the radio frequency （RF） power amplifier system is reducing its complexity of engineering realizati...At present what are the key points focused in the research of loop-delay estimation for the digital predistorter in the radio frequency （RF） power amplifier system is reducing its complexity of engineering realization and improving anti-jamming ability and computational speed. Besides, opening up its application scope should be contained. For these targets, a novel method including integer loop delay estimation and fractional part is proposed. The integer part applies amplitude-difference summation function and the fractional one adopts the method of finite impulse response （FIR） linear interpolation. The algorithm finds wide applications. What is more, strong anti-jamming ability and low complexity are also its merits. Simulation results support the above opinion. Digital predistortion （DPD） system based on this algorithm achieves good performance.展开更多
Different power amplifier （PA） models have their own effects on PA linearization. In this paper, the nonlinear characteristic of the radio frequency power amplifier （RF PA） is simulated based on the two models com...Different power amplifier （PA） models have their own effects on PA linearization. In this paper, the nonlinear characteristic of the radio frequency power amplifier （RF PA） is simulated based on the two models combining predistortion technology, and the nonlinear effects of the two models are analyzed, respectively. The simulation results show that Power Series model normalized mean square error （NMSE） is -37.8 dB, which is less than Power Series model -30.4 dB before loading predistortion technology. NMSE of the two systems are -23.4 dB and -26.0 dB respectively, while Saleh model compensates better than the Power Series model combing predistortion technology. The error vector magni- tude （EVM） of Power Series model is only 6.75%, whereas the Saleh model EVM is 9.99%, indicating that Power Series model can better describe the nonlinear characteristic of PA. It will have a positive effect on improving the power utilization of wireless communication system.展开更多
This paper proposes that a radio frequency power amplifier is suitable for a 5G millimeter wave.It adopts a three-stage single-ended structure at 28GHz.An analog predistortion lmearization method is used to improve th...This paper proposes that a radio frequency power amplifier is suitable for a 5G millimeter wave.It adopts a three-stage single-ended structure at 28GHz.An analog predistortion lmearization method is used to improve the linearity of the power amplifier(PA).As a result,there is a significant improvement in power-added efficiency(PAE)and linearity is achieved.The Ka-band PA is implemented in TSMC 65nm CMOS process.At 1.2V supply voltage,the PA proposed in this paper achieves a saturated output power of 15.9dBm and a PAE of 16%.After linearization,the output power at the ldB compression point is increased by 2dBm,with efficient gain compensation performance.展开更多
基金supported by ZTE Industry-University-Institute Cooperation Funds under Grant No.HC-CN-20220722010。
文摘This paper proposes a concurrent neural network model to mitigate non-linear distortion in power amplifiers using a basis function generation approach.The model is designed using polynomial expansion and comprises a feedforward neural network(FNN)and a convolutional neural network(CNN).The proposed model takes the basic elements that form the bases as input,defined by the generalized memory polynomial(GMP)and dynamic deviation reduction(DDR)models.The FNN generates the basis function and its output represents the basis values,while the CNN generates weights for the corresponding bases.Through the concurrent training of FNN and CNN,the hidden layer coefficients are updated,and the complex multiplication of their outputs yields the trained in-phase/quadrature(I/Q)signals.The proposed model was trained and tested using 300 MHz and 400 MHz broadband data in an orthogonal frequency division multiplexing(OFDM)communication system.The results show that the model achieves an adjacent channel power ratio(ACPR)of less than-48 d B within a 100 MHz integral bandwidth for both the training and test datasets.
基金Project (No. 60372026) supported by the National Natural ScienceFoundation of China
文摘RF power amplifiers (PAs) are usually considered as memoryless devices in most existing predistortion techniques. Nevertheless, in wideband communication systems, PA memory effects can no longer be ignored and memoryless predistortion cannot linearize PAs effectively. After analyzing PA memory effects, a novel predistortion method based on wavelet networks (WNs) is proposed to linearize wideband RF power amplifiers. A complex wavelet network with tapped delay lines is applied to construct the predistorter and then a complex backpropagation algorithm is developed to train the predistorter parameters. The simulation results show that compared with the previously published feed-forward neural network predistortion method, the proposed method provides faster convergence rate and better performance in reducing out-of-band spectral regrowth.
基金The National Natural Science Foundation of China(No.60702163)the National Science and Technology Major Project(No.2010ZX03007-002-01,2011ZX03004-003)
文摘A digital predistorted class-F power amplifier （PA） using Cree GaN HEMT CGH40010 operating at 2. 12 GHz is presented to obtain high efficiency and excellent linearity for wideband code-division multiple access （ WCDMA ） applications. Measurement results with the continuous wave （CW） signals indicate that the designed class-F PA achieves a peak power-added efficiency （PAE） of 75. 2% with an output power of 39.4 dBm. The adjacent channel power ratio （ACPR） of the designed PA after digital predistortion （DPD） decreases from -28. 3 and -27. 5 dBc to -51.9 and -54. 0 dBc, respectively, for a 4-carrier 20 MHz WCDMA signal with 7. 1 dB peak to average power ratio （PAPR）. The drain efficiency （DE） of the PA is 37. 8% at an average output power of 33. 3 dBm. The designed power amplifier can be aoolied in the WCDMA system.
文摘To compensate for nonlinear distortion introduced by RF power amplifiers （PAs） with memory effects, two correlated models, namely an extended memory polynomial （EMP） model and a memory lookup table （LUT） model, are proposed for predistorter design. Two adaptive digital predistortion （ADPD） schemes with indirect learning architecture are presented. One adopts the EMP model and the recursive least square （RLS） algorithm, and the other utilizes the memory LUT model and the least mean square （LMS） algorithm. Simulation results demonstrate that the EMP-based ADPD yields the best linearization performance in terms of suppressing spectral regrowth. It is also shown that the ADPD based on memory LUT makes optimum tradeoff between performance and computational complexity.
文摘This paper presents a dual-nonlinear branch linearizer for reducing the corrected amplitude overshoot of conventional single nonlinear branch linearizer. Theoretical analysis is carried out, the analysis is verified by simulation, and a prototype of Ka band 25.28~26.08 GHz dual nonlinear branch linearizer is achieved. It indicates that the corrected amplitude overshoot is less than 0.5 dB, the C/I3 improvement is more than 10 dB related to a single carrier IBO 9 dB, when it is linked and tested for 50 W spacebrone Travelling Wave Tube Amplifier(TWTA).
基金National Key R&D Program of China under Grant No.2018YFB1801603 and No.2017YFF0206201National Sci⁃ence and Technology Major Project under Grant 2017ZX03001024,NSFC under Grant No.61801259 and Beijing National Research Center for Infor⁃mation Science and Technology(BNRist).
文摘A robust digital predistortion(DPD)technique utilizing negative feedback iteration is introduced for linearizing power amplifiers(PAs)in long term evolution(LTE)/5G systems.Different from the conventional direct learning and indirect learning structure,the proposed DPD suggests a two-step method to identify the predistortion.Firstly,a negative feedback based iteration is used to estimate the optimal DPD signal.Then the corresponding DPD parameters are extracted by forward modeling with the input signal and optimal DPD signal.The iteration can be applied to both single-band and dual-band PAs,which will achieve superior linear performance than the conventional direct learning DPD while having a relatively low computational complexity.The measurement is carried out on a broadband Doherty PA(DPA)with a 200 MHz bandwidth LTE signal at 2.1 GHz,and on a 5G DPA with two 10 MHz LTE signals at 3.4/3.6 GHz for validation in dual-band scenarios.
基金supported by Shenzhen Strategic Emerging Industry Development Fund Project——Public service platform for 5G key components testing(20170921165224440)
文摘Digital PreDistortion(DPD)is a very useful method to improve the linearity of Power Amplifiers(PAs)for LTE and upcoming 5 G networks.As the spectrum resources are becoming more and more crowded,and the communications bandwidth are broader,the ACPR(Adjacent Channel Leakage Ratio)is very important to communication systems.DPD is one of the useful means for PA to reduce ACPR.This article demonstrates what DPD is and how DPD is achieved,the measurement of the Digital Distortion of a PA using a vector generator and vector analyzer,and the measurement results has been discussed.
基金the National Natural Science Foundation of China (60671037).
文摘RF power amplifiers （PAs） are usually considered as memoryless devices in most existing predistortion techniques. However, in broadband communication systems, such as WCDMA, the PA memory effects are significant, and memoryless predistortion cannot linearize the PAs effectively. After analyzing the PA memory effects, a novel predistortion method based on the simplified Volterra series is proposed to linearize broadband RF PAs with memory effects. The indirect learning architecture is adopted to design the predistortion scheme and the reeursive least squares algorithm with forgetting factor is applied to identify the parameters of the predistorter. Simulation results show that the proposed predistortion method can compensate the nonlinear distortion and memory effects of broadband RF PAs effectively.
基金supported by the Circuit and System Foremost Discipline of Zhejiang Province under Grant No. ZZ050103-11
文摘At present what are the key points focused in the research of loop-delay estimation for the digital predistorter in the radio frequency （RF） power amplifier system is reducing its complexity of engineering realization and improving anti-jamming ability and computational speed. Besides, opening up its application scope should be contained. For these targets, a novel method including integer loop delay estimation and fractional part is proposed. The integer part applies amplitude-difference summation function and the fractional one adopts the method of finite impulse response （FIR） linear interpolation. The algorithm finds wide applications. What is more, strong anti-jamming ability and low complexity are also its merits. Simulation results support the above opinion. Digital predistortion （DPD） system based on this algorithm achieves good performance.
基金Supported by the Research Project of Department of Education Hubei Provincial(B2016206)the Huanggang Normal University Science and Technology Innovation Team Program(201613603)
文摘Different power amplifier （PA） models have their own effects on PA linearization. In this paper, the nonlinear characteristic of the radio frequency power amplifier （RF PA） is simulated based on the two models combining predistortion technology, and the nonlinear effects of the two models are analyzed, respectively. The simulation results show that Power Series model normalized mean square error （NMSE） is -37.8 dB, which is less than Power Series model -30.4 dB before loading predistortion technology. NMSE of the two systems are -23.4 dB and -26.0 dB respectively, while Saleh model compensates better than the Power Series model combing predistortion technology. The error vector magni- tude （EVM） of Power Series model is only 6.75%, whereas the Saleh model EVM is 9.99%, indicating that Power Series model can better describe the nonlinear characteristic of PA. It will have a positive effect on improving the power utilization of wireless communication system.
文摘This paper proposes that a radio frequency power amplifier is suitable for a 5G millimeter wave.It adopts a three-stage single-ended structure at 28GHz.An analog predistortion lmearization method is used to improve the linearity of the power amplifier(PA).As a result,there is a significant improvement in power-added efficiency(PAE)and linearity is achieved.The Ka-band PA is implemented in TSMC 65nm CMOS process.At 1.2V supply voltage,the PA proposed in this paper achieves a saturated output power of 15.9dBm and a PAE of 16%.After linearization,the output power at the ldB compression point is increased by 2dBm,with efficient gain compensation performance.
