第五届集创赛——IEEE杯
IEEE杯
¨ 杯赛题目：28GHz高能效PA设计（Outphasing or Doherty Topology）
¨ 参赛组别：A组、B组
¨ 设计任务：
1. 设计一个满足性能要求的工作在28GHz的功率放大器，电路性能强调在达到一定的输出功率与线性度的条件下，平均输出功率的高能量转换效率（peak and PBO）。建议采用Outphasing拓扑结构。
¨ 设计指标：
1. 工作频率28GHz
2. 采用架构（architecture）由并联电路拓扑Outphasing或Doherty PA任选一
3. Psat及增益：22dBm/12dB
4. 效率: peak PAE and at PBO (Power Back-Off，功率回退) of 6dB 不低于35%与25%（参考值）
5. 线性度: P1dB 为20dBm
6. 采用Cadence 45nm CMOS GPDK工艺库或各校自有的45/55/65nm PDK；
¨ 提交内容：
设计文档需有PA系统级仿真及一路常幅信号功率放大器与功率合成器的电路/版图设计与后仿结果。
1. 电路设计定性思路
1) 电路系统框图
2) 各电路模块实现的功能
3) 电路性能指标分配
2. 电路网表与模拟（采用PDK提供的器件模型）
3. 有选择性的电路模块版图实现及后仿
1) 单路恒幅高效电路
2) 功率合成器
4. 总结：设计的特点、实现了的性能分析，与改进建议等
¨ 评分标准
内容 | 分值 | 评分标准 |
1. 完成28GHz高能效PA设计的调研 | 15 | 1. 了解目前毫米波PA提高能效的几种方式 2. 理解赛题要求的doherty和outphasing的工作原理 3. 完成电路架构的选择并阐述原因 |
2.完成PA的定性设计 | 20 | 1. 画出电路系统框图 2. 计划各个模块所需要的功能 3. 完成电路性能指标的分配 |
3.完成PA的基本电路设计（不需要版图，但是所有有源元件需要考虑寄生参数（可以采用rf元件），所有的无源元件需要采用pdk提供的元件或者进行EM仿真） | 40 | 1. 实现PA中各个电路模块的功能 2. 实现各个模块所预定的性能 3. 实现完整PA系统的性能指标 |
4.完成电路的版图设计 | 15 | 1. 有选择性的电路模块版图实现 2. 完成带有版图的整体电路的后仿 3. 达到完整PA系统的性能指标 |
5.现场答辩和演示 | 10 | 答辩和问答表现 |
¨ 赛题补充说明：
1. 5G CMOS-射频前端(FE)电路设计赛题回顾：2017: 宽带sub-6GHz LNA设计；2018: 覆盖28-39GHz PLL设计；2019: 采用包络跟踪(ET: Envelope Tracking)架构的适用于LTE/5G通信的PA设计；2020: 28GHz相控阵收发器阵列的单元设计与系统验证
2. GPDK是开源的pdk，网上可以下载，其基本性能可以支持设计，只是电感等部分元件库可能会不全，需要设计人员自己做一些EM仿真。
3. 背景材料介绍（Jijun Bi, TU Delft MS Thesis, 2008）
1) 效率与线性度的折衷（Efficiency and linearity trade-off） in RF power amplifiers
2) ET (Envelop Tracking) vs. Outphasing Pas：In envelope tracking, the supply modulator (SM) must have a continuously variable output. Achieving the required modulation bandwidth, which must be at least five times that of the signal for linearization, is very difficult and currently the bottleneck of the ET PA. Additionally, SM must be able to swing the voltage very fast for high PAPR signals, while providing a lot of power, corresponding to a very high slew rate.
For practical implementations of the Chireix’s outphasing amplifier, a common-mode power combiner realized by quarter-wavelength transmission lines is usually adopted
3) Outphasing PA：Outphasing is a popular RF transmitter (TX)/PA topology to achieve large power-back-off (PBO, 回退) efficiency enhancement together with high peak efficiency.
A typical Outphasing architecture consists of two TX/PA branches that operate with their saturated voltage swings but dynamically varying phase difference to realize active load modulation at PBO
4) Outphasing PA原理图：
5) Common Mode Combiner in Outphasing Amplifier (OA)：Having an influence both on the efficiency and on the linearity, the power combiner is a place where the efficiency-linearity tradeoff needs to be dealt with.
The Chireix’s outphasing operation requires the two PAs to resemble a behavior that approximates a voltage source. Relevant work has shown that saturated class-B, class-F, and voltage-mode class-D PAs have an output current-voltage relationship that is similar to that of a voltage source.
4. 本设计不包括SCS模块，采用信号发生器来产生两路输入信号：S1，S2
For this digital SCS implementation we will rely on arbitrary waveform generators (AWG) and I/Q (In-phase/Quadrature) up-converting modulators to generate the two phase modulated RF input signals. Software will be used to implement the AM-PM signal conversion.
5. 参考设计（S. Li of GIT, 2020 ISSCC：S. Li, “A 28GHz Current-Mode Inverse-Outphasing Transmitter Achieving 40%/31% PA Efficiency at Psat/6dB PBO and Supporting 15Gbit/s 64-QAM for 5G Communication”, ISSCC 2020, p. 366
6. Choice of Combiners（功率合成器的选择）：
1) Basically there are two kinds of power combiners: isolating power combiners and nonisolating lossless power combiners.
2) An isolating power combiner provides isolation between its input ports. In a classical LINC system that employs isolating power combiners, the inherent high linearity of the LINC operation can be preserved, but the considerable power loss in the combiners results in significant efficiency reduction.
3) A nonisolating lossless power combiner in the PA output yields significant interaction between the amplifiers, which leads to AM-AM and AM-PM distortion, however it provides a much better efficiency.
¨ 参考资料：
1. B. Rabet (UCSD), “A High-Efficiency 28GHz Outphasing PA with 23dBm Output Power Using a Triaxial Balun Combiner,” ISSCC 2018
Average PAE: 25.3% in UCSD 2018 ISSCC SiGe OPA (triaxial balun outphasing PA)
2. B. Rabet and P. M. Asbeck, "A 28 GHz Single-Input Linear Chireix (SILC) Power Amplifier in 130 nm SiGe Technology," JSSC, vol. 55, no. 6, pp. 1482-1490, 2020
3. S. Li (GIT), “A 28-GHz Flip-Chip Packaged Chireix Transmitter With On-Antenna Outphasing Active Load Modulation,” JSSC 2019
4. S. Li (GIT), “A 28GHz Current-Mode Inverse-Outphasing Transmitter Achieving 40%/31% PA Efficiency at Psat/6dB PBO and Supporting 15Gbit/s 64-QAM for 5G Communication,” ISSCC ’20
5. F. Wang (GIT), “A 24-to-30GHz Watt-Level Broadband Linear Doherty Power Amplifier with Multi-Primary Distributed-Active-Transformer Power-Combining Supporting 5G NR FR2 64-QAM with >19dBm Average Pout and >19% Average PAE,” ISSCC 2020
6. N. Rostomyan (UCSD), “28 GHz Doherty Power Amplifier in CMOS SOI With 28% Back-Off PAE,” MWCL 2018
7. S. Jia (Tsinghua), “A Novel Doherty Transmitter Based on Antenna Active Load Modulation,” MWCL 2015
8. TU Delft MS thesis in 2008: Jijun Bi, “Chireix’s / LINC Power Amplifier for Base Station Applications Using GaN Devices with Load Compensation”
9. U Colorado Ph.D. thesis in 2016: Michael Philip Litchfield, “Efficiency Enchancement Techniques for the Outphasing Power Amplifier”
其他注意事项：
1、参加企业命题杯赛的作品，杯赛出题企业有权在同等条件下优先购买参加本企业杯赛及单项奖获奖团队作品的知识产权。
2、大赛组委会对参赛作品的提交材料拥有使用权和展示权
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