输入端谐波抑制S波段高效率F类功率放大器的研究

传统的F类功率放大器设计方法是对其输出端进行谐波抑制,在输出端得到近似方波的电压信号和近似半正弦波的电流信号,以此提高放大器效率.新型高效率F类功率放大器在输入端加入谐波抑制电路,同时利用输入和输出谐波抑制匹配网络能够有效提高输出功率和功率附加效率;在S波段完成一款电路的设计并进行测试,在电路设计中采用新的负载牵引、源牵引仿真方法,实验结果和仿真结果非常吻合.在输入激励为28dBm条件下,测试结果表明,最大PAE能够达到75.4%,输出功率40.3dBm.     

输入端谐波抑制的高效E类宽禁带功率放大器

文章提出对E类功率放大器进行谐波抑制的改进设计方法,有效利用输入端信号功率,从而提高功放的功率附加效率;分析了E类功率放大器的工作原理,结合新型宽禁带功率器件利用ADS软件进行了电路仿真设计,并对实际放大器电路进行了实际测试。结果表明,对输入端谐波抑制的改进可以使功率放大器在1.1～1.3GHz频段内输出功率保持在10W以上,功率附加效率达到了79.6%,比改进前E类功率放大器的效率有了明显的提高。     

基于GaN器件的平衡式逆F类功率放大器的研究与设计

针对功率放大器效率低和输入输出端反射损耗较大的缺陷,采用平衡式结构研究了工作于2.6 GHz的逆F类功率放大器,并基于GaN器件CGH40010F设计该放大器验证电路。根据功放管输出寄生参数的等效网络,将负载阻抗转换到封装参考面上,在输出匹配电路中对二、三次谐波进行抑制处理。并且考虑栅源寄生电容对输入信号的影响,在输入拓扑结构中加入二次谐波抑制电路,进一步提高了放大器的效率。同时,在栅漏极偏置电路中,采用扇形微带线代替短路电容,使电路结构更为紧凑。经仿真优化,采用Rogers4350b板材制作该功放电路板。实测表明,饱和输出功率为42.32 dBm,最大漏极效率为77.91%,最大功率附加效率(power added efficiency, PAE)达到72.16%,输入输出驻波系数(voltage standing wave ratio, VSWR)均小于2。实测结果与仿真数据基本吻合,验证了设计方法的可行性。     

应用于WLAN的高效率F类功率放大器

为了提高在高速率信号传输下无线通讯发射系统中功率放大器的工作效率,提出了一种结构新颖的高效率F类功率放大器.通过计算机仿真与实验板调试相结合的方法确定了放大器的最佳漏极阻抗,根据F类放大器漏极电压和漏极电流是相位差为λ/4的方波和半正弦波的特性,通过仿真软件设计和优化,设计出的谐波滤波网络在输出谐波频点有良好的滤波性能.为了降低栅源电容对输入信号造成的失真,在输入端口加入短截线,提高了放大器的漏极效率.通过测试,功率放大器工作在2.4GHz时,在2dB增益压缩点的功率附加效率为67%,输出功率为30dBm.测试结果表明,该高效率功率放大器适合应用于WLAN无线通讯发射系统.     

S波段高效E类GaN HEMT功率放大器设计

为了解决E类功率放大器最大工作频率(f max )受晶体管输出电容限制的问题,提出了一种新型的E类功率放大器输出匹配电路结构.该结构能够同时实现对晶体管在基波和谐波下的过剩输出电容进行补偿,一方面提升了E类功率放大器在高频工作时的效率,另一方面也降低了电路的复杂度和实现难度.利用所提出的方法,采用GaN HEMT器件,设计并实现了工作在2.5 GHz的E类功率放大器.测试结果表明,其最大功率附加效率(PAE)达到80%,饱和输出功率为40.1 dBm.     

基于ADS平台反向Doherty结构的功率放大器的设计与仿真

基于Advanced design system(ADS)平台,通过优化偏置电压和输入功率比例改善三阶互调失真(IMD3),仿真设计一款工作于2.14 GHz频段WCDMA基站不对称功率驱动的反向Doherty功率放大器(IDPA).IDPA结构中接在峰值放大器补偿线后的微带线能减少功率泄露,改善输出效率.仿真结果表明,当载波放大器的栅极偏置电压为2.74 V,峰值放大器的栅极偏置电压为0.9 V并且输入功率比例为1∶2.07,输出功率为44 dBm时其功率附加效率(PAE)为25.26%,比AB类平衡功率放大器提高了9.63%,比传统的Doherty功率放大器(DPA)提高了1.12%;IMD3为-40.82dBc,和AB类平衡功率放大器相比改善了3.34 dBc.因此,这种简单结构的不对称功率驱动的IDPA实现了高效率和高线性度的良好折中,能够很好地适用于现代无线通信系统中.     

应用于WLAN的GaAs HBT功率放大器设计

提出了一款基于GaAs HBT工艺的高功率功率放大器（Power Amplifier,PA）.设计采用三级放大器级联的结构以提高功率放大器的功率增益,在功率晶体管的基极处串联RC有耗稳定网络来提高稳定性及改善增益平坦度,采用电流镜有源偏置的方式提升大信号输出时的功率、效率及线性度表现,同时在输出级放大器处添加功率检测电路以得到随输出功率变化的直流电压信号.EM仿真结果表明：PA的输出频率范围为5.1~6.5 GHz,增益为33~33.7 dB,S11、S22<-9.8 dB,饱和输出功率为32.8~34.9 dBm,峰值效率为38.7 %~42 %,在满足无线局域网标准802.11ax、调制策略为MCS7的情况下,EVM达到-30 dB时输出功率为20~21 dBm,芯片面积为1.69 mm×0.73 mm.测试结果表明：S参数测试结果与仿真结果表现出较好的一致性,PA在满足前述无线局域网标准时输出功率为13.6~19.8 dBm.     

一种新型谐波抑制负载结构的整流电路

为了满足5G大环境下的低功耗物联网节点应用,设计了一种新型谐波抑制负载结构的整流电路,在二极管后引入连续多阶微带谐波抑制结构,从而实现较高的转换效率和较小的输出纹波.该电路结构紧凑、设计成本低、结构简单,当输入功率为14.8 dBm时,电路的转换率可达72.5％.最后选择F4B基板进行实验验证,结果表明当负载为750 Ω时,该电路结构的最高转换效率仍可以达到61.2％,相比于其他结构有明显的提高.     

基于谐波抑制与补偿线技术的非对称Doherty功放设计

为了提高WiMAX信号下doherty功率放大器（doherty power amplifier,DPA）回退点的效率,提出一种基于谐波抑制和补偿线技术的非对称doherty功放（asymmetric doherty power amplifiers,ADPA）结构。该结构在传统ADPA结构的基础上,首先对主功放（carrier）和辅功放（peak）输出匹配电路加入2次、3次谐波电路进行匹配设计,减少晶体管漏极电压电流的重合;然后通过添加补偿线（offset line）的方式,改变carrier和peak的功率分配比,使得整体电路获得更高的效率和输出功率。基于上述谐波抑制和补偿线理论,设计了一款工作在3.4 GHz~3.6 GHz,增益约为13 dB的ADPA。实测结果表明,当饱和输出功率达到48.75 dBm,功率回退9.5 dB时,功率附加效率（power added efficiency,PAE）达到41.8%,5 MHz偏移量的相邻信道功率比（adjacent channel power ratio,ACPR）优于-35 dBc,10 MHz偏移量的ACPR优于-48 dBc。满足WiMAX基站对功放线性度和效率的要求。     

3.43 GHz SiGe BiCMOS功率放大器设计

采用AMS 0.35μm SiGe BiCMOS工艺,设计了用于卫星通信用的3.33-3.53 GHz功率放大器.该功率放大器采用单端结构,工作于A类.在3.3 V电源电压下,功率放大器的功率增益为22.3 dB,输出1 dB压缩点为31.9 dBm,相应的功率附加效率为25.2%.仿真结果表明,该功率放大器具有良好的输入、输出匹配,工作稳定.     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that