
Citation: | YANG Zhigang, WANG Zhuotong, WU Dapeng, WANG Ruyan, WU Yu, LÜ Yi. Research on Data Heterogeneous Robust Federated Learning with Privacy Protection in Internet of Things[J]. Journal of Electronics & Information Technology, 2023, 45(12): 4235-4244. doi: 10.11999/JEIT221193 |
无线通信领域每一次技术更新都伴随着带宽的拓展,以支持更大的数据传输速率和数据容量。射频功率放大器(功放)作为无线通信系统中最重要的有源模块,其性能的好坏直接影响着无线通信系统性能的通信质量。因此宽带高效率功率放大器的设计仍然是当今研究的热点。而宽带功率放大器设计的难点在于宽带范围内功放的最优阻抗随频率会有较大的变化,关键在于如何选取一个最优阻抗解使得其在宽带范围内得到最优阻抗以及宽带匹配网络的设计。而传统的A, AB, B, C类功放很难在宽带范围内同时实现高效率和高输出功率。而D, E类等开关类功放在GHz以上频段会发生波形失真,且受到功放器件的开关限制,很难有实际用途[1,2]。F类功放则需要对高次谐波进行精确的控制,在宽带范围内很难实现。由Cripps等人[3]在2009年提出一种新型谐波控制类功放即J类功放,它相比于F类功放二次谐波阻抗不再需要严格的开路或者短路,使得J类功放具有实现宽带的潜力。而在J类功放的基础上提出的连续功率放大器,相比于对各次谐波和基波阻抗进行精确控制的传统谐波控制类型,连续型功放模式有着较为丰富的最佳阻抗解空间,简化宽带匹配网络的设计复杂度[4,5]。而混合连续类功放在包含连续F类与连续B/J类的基础上将阻抗解空间进一步扩大,相比于传统连续类它实现宽带功放的潜力更大。
本文首先分析混合连续类的漏极电压公式进而推导出阻抗设计空间,然后通过使用一种新型的谐波网络,再采用阶跃阻抗低通滤波结构作为输出匹配网络,最后基于功率密度大、击穿电压高、电子饱和漂移速度高的第3代半导体GaN HEMT[6,7]设计了一款性能优越的超宽带功放。
最早由英国卡迪夫大学的Cripps等人[3]提出的F,J类功放通过降低导通角来提高功放的效率。通过假定电流谐波分量在器件输出端为短路状态,保证了功放输出电压波形为正弦波[8]。在Cripps等人推导过程中定义归一化电压公式为
v(θ)=1−v1rcosθ+v1q+∑nvnqsin(nθ) | (1) |
随着
v(θ)=(1−cosθ)⋅(1−αsinθ),−1<α<1 | (2) |
当
vCF=(1−2√3cosθ)2⋅(1+1√3cosθ)⋅(1−βsinθ) | (3) |
其中,
vDS(θ)=(1−α′cosθ+β′cos3θ)⋅(1−γsinθ),−1<γ<1 | (4) |
当
根据电压电流表达式可以推导出它在电流源平面下的基波阻抗及2次谐波阻抗
Z1=Ropt⋅(α′+jγ)Z2=−3π8Ropt⋅γ⋅(α′+β′) | (5) |
其中,
“波形工程”的主要思想在于通过合理的增加谐波分量来调控电压和电流波形使得功率管漏极输出电压和电流发生较小的重叠,从而减小漏极功率消耗,同时保证较好的谐波抑制,从而在较宽的频带范围内维持高效率[10,11]。在新型连续性的拓展中,在保证某一固定偏置下,通过对谐波以及基波阻抗成分进行调整,控制晶体管的漏极电流与电压之间的重叠尽可能减小,使得该连续型模型在一个更为宽泛的阻抗解空间中保持合适的输出功率以及效率。
图3是本文所采用的谐波控制网络,该谐波控制网络是基于中心频率IB(Impedance Buffer)[12,13]理论所设计的。通过将1/4波长的开路短截线与半波长短路短截线并联实现对功放谐波控制。其中
Z0(3f0)=j⋅ZL1⋅tan(θL13f0) | (6) |
其中,
θL13f0=arctan(Z0(3f0)jZL1) | (7) |
通过在
θL22f0=arctan(Z′1(2f0)jZL2) | (8) |
而平面
Z′(2f0)=jZ1(2f0)ZS1cot(π2.2f03f0)2Z1(2f0)+jZS1cot(π2.2f03f0) | (9) |
在平面
Z1(2f0)=ZL1⋅Z0(2f0)−jZL1tan(θS13f0⋅2f03f0)ZL1−jZ0(2f0)tan(θS13f0⋅2f03f0) | (10) |
其中,
由于谐波网络已经将2次谐波阻抗控制在高效率和高输出功率区域并且尽量维持在Smith边缘,因此输出匹配网络主要完成对基波阻抗匹配。为了实现对基波匹配网络的精确设计,在大信号模型下采用负载牵引技术得到最优基波阻抗。并采用最平坦低通原型结构[14],利用阶梯阻抗变换线[15,16]将最优负载阻抗匹配到
本次设计采用的晶体管为Cree公司的CGH40010F GaN HEMT的封装功放管,漏极电压为28 V,栅极电压为–2.8 V,采用Rogers4003C的介质基板,介电常数3.38厚度为0.813 mm。整体电路的结构如图6所示。
图7给出了在大信号下ADS仿真电压电流波形,可以看出电压电流波形基本上满足连续F类与连续B/J类的电压电流波形形式,并且电压幅度接近
采用Rogers 4003c板材加工的功放PCB实物照片如图8所示。进行大信号测试功放的输出功率、漏极效率、功率附加效率、增益和仿真的结果如图9所示。最终在0.3~3.5 GHz频段内得到的增益为10~18 dB,漏极效率为58.4%~72.6%,输出功率为39.8~41.2 dBm。表1是与近些年来国内外相关功放设计的效果对比。
文献对比 | 工作模式 | 频率(GHz) | BW(%) | PAE(%) | DE(%) | 增益(dB) | Pout(dBm) | 年份 |
文献[2] | F类/逆F类 | 2.4~4.2 | 54.5 | – | 55.0~82.0 | 11~13.6 | 39.5~41.9 | 2019 |
文献[11] | 连续类 | 0.8~3.6 | 127.0 | – | 55.8~74.1 | 10.2~12.2 | 39.5~42.1 | 2016 |
文献[13] | 连续F类 | 0.5~2.3 | 128.5 | 52.7~80.7 | 60.0~81.0 | 11.7~25.3 | 39.2~41.2 | 2017 |
文献[15] | BJ类/F-1类 | 2.2~2.8 | 24.0 | 58.0~75.0 | 65.9~79.7 | 12.0~18.0 | 41.0~43.0 | 2019 |
文献[16] | 连续B/J类 | 1.2~2.6 | 74.0 | – | 63.0~68.0 | 10.0~13.6 | 40.5~41.6 | 2018 |
本文 | 混合连续 | 0.3~3.5 | 168.4 | – | 58.4~72.6 | 10.0~18.0 | 39.8~41.2 | 2019 |
本文通过分析连续F类、B/J类功放电压波形确定混合连续类功放的阻抗设计空间,基于阻抗缓冲(IB)概论提出了一种设计谐波网络的方法,有效地将基波、2次谐波和3次谐波的阻抗控制到理论提出的设计空间内。本文采用Cree公司的CGH40010F GaN HEMT的功放管,设计一款宽带跨3个倍频程的混合连续类功放。在实际测量中在0.3~3.5 GHz内有58.4%以上的漏极效率,输出功率有39.8 dBm以上。
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文献对比 | 工作模式 | 频率(GHz) | BW(%) | PAE(%) | DE(%) | 增益(dB) | Pout(dBm) | 年份 |
文献[2] | F类/逆F类 | 2.4~4.2 | 54.5 | – | 55.0~82.0 | 11~13.6 | 39.5~41.9 | 2019 |
文献[11] | 连续类 | 0.8~3.6 | 127.0 | – | 55.8~74.1 | 10.2~12.2 | 39.5~42.1 | 2016 |
文献[13] | 连续F类 | 0.5~2.3 | 128.5 | 52.7~80.7 | 60.0~81.0 | 11.7~25.3 | 39.2~41.2 | 2017 |
文献[15] | BJ类/F-1类 | 2.2~2.8 | 24.0 | 58.0~75.0 | 65.9~79.7 | 12.0~18.0 | 41.0~43.0 | 2019 |
文献[16] | 连续B/J类 | 1.2~2.6 | 74.0 | – | 63.0~68.0 | 10.0~13.6 | 40.5~41.6 | 2018 |
本文 | 混合连续 | 0.3~3.5 | 168.4 | – | 58.4~72.6 | 10.0~18.0 | 39.8~41.2 | 2019 |
文献对比 | 工作模式 | 频率(GHz) | BW(%) | PAE(%) | DE(%) | 增益(dB) | Pout(dBm) | 年份 |
文献[2] | F类/逆F类 | 2.4~4.2 | 54.5 | – | 55.0~82.0 | 11~13.6 | 39.5~41.9 | 2019 |
文献[11] | 连续类 | 0.8~3.6 | 127.0 | – | 55.8~74.1 | 10.2~12.2 | 39.5~42.1 | 2016 |
文献[13] | 连续F类 | 0.5~2.3 | 128.5 | 52.7~80.7 | 60.0~81.0 | 11.7~25.3 | 39.2~41.2 | 2017 |
文献[15] | BJ类/F-1类 | 2.2~2.8 | 24.0 | 58.0~75.0 | 65.9~79.7 | 12.0~18.0 | 41.0~43.0 | 2019 |
文献[16] | 连续B/J类 | 1.2~2.6 | 74.0 | – | 63.0~68.0 | 10.0~13.6 | 40.5~41.6 | 2018 |
本文 | 混合连续 | 0.3~3.5 | 168.4 | – | 58.4~72.6 | 10.0~18.0 | 39.8~41.2 | 2019 |