随着第五代移动通信技术和军用电子对抗系统的发展，射频前端电路工作的频率范围和承载的数据率均在不断增加，射频电路往往需要集成更多的收发通道以满足系统要求。为了减小芯片面积、降低制造成本，可设计覆盖多个通信频带的宽带射频前端电路，或收发同时工作的全双工射频前端。本文针对第五代移动通信和军用电子对抗系统的小型化问题，采用体硅CMOS工艺，对宽带射频前端和全双工射频前端进行了研究。针对无源器件的建模分析和损耗优化是设计射频电路的基础，对称电感是射频电路中最常用的无源器件之一。本文首先针对对称电感进行了建模，采用了曲线拟合和算法优化的参数提取方法，在0-110GHz范围内，模型感值和品质因子的均方根误差小于1.07%，为后续的宽带匹配理论设计和射频电路的前仿真设计打下了基础。此外，本文还设计了基于浮空金属屏蔽层的毫米波衬底损耗优化方法，通过将屏蔽层与电感拉开一定距离以有效吸收电场线同时不引入显著的寄生电容，在110GHz实现了3.4%的品质因子提升。针对宽带射频前端电路,本文首先推导了基于有损变压器的宽带匹配理论，得到了有损情况下的匹配网络设计方程，解决了损耗造成的带内增益波动问题。在此基础上，本文设计了一款全差分宽带功率放大器（PA），通过调谐各级匹配网络使其具有特定的幅频响应曲线，可实现对PA带宽的精确控制。测试结果显示，该宽带PA实现了23-39GHz的3dB小信号增益（S21）带宽和23.8-38.1GHz的1dB饱和输出功率（Psat）带宽。此外，本文还设计了一款分布式宽带PA，采用分布式结构以提升小信号带宽，采用4晶体管堆叠的结构以提升增益和输出功率。测试结果显示，所设计的分布式PA实现了2-15.4GHz的3dB S21带宽，19.2dB的最大S21和20.9dBm的最大Psat。针对全双工射频前端电路,本文设计了一款28GHz全双工射频前端电路，集成了电平衡双工器（EBD），低噪声放大器（LNA）和PA。EBD采用了混合变压器结构以隔离PA和LNA并同时提供阻抗匹配。经仿真验证，EBD在28GHz实现了38.6dB的隔离度，保证了全双工系统的正常工作。全双工射频前端的Psat为10.8dBm，噪声系数为6.1dB。

With the development of 5G technology and military electronic countermeasure systems, radio-frequency (RF) front-end chips are facing increasingly severe challenges in the operating frequency range and data rate. In order to satisfy the system performance requirement, more and more receiving and transmitting channels usually have to be integrated. In order to reduce chip size and manufacturing costs, broadband RF front-end chips covering multiple frequency bands and full-duplex RF front-end chips receiving and transmitting signals simultaneously can be adopted. In this thesis, both broadband RF front-end circuits and full-duplex RF front-end circuits are studied using bulk CMOS process to facilitate the miniaturization of 5G communication and military electronic countermeasure systems.Modeling, analysis and optimization of passive devices are the foundation of RF front-end circuits design, the symmetrical inductor is one of the most commonly used passive device in RF front-end circuits. First of all, modeling of symmetrical inductors is studied, which is based on the proposed parameter extraction procedure consisting of curve fitting and algorithm optimization. In 0-110GHz, the root-mean-square error of the modeled inductance and quality factor is less than 1.07%. The modeling of symmetrical inductors facilitates the following broadband matching theory and pre-layout simulation of RF front-end circuits. Besides, a floating metal shield is proposed to reduce the substrate-induced loss in millimeter-wave frequency. By setting a proper distance between the metal shield and the inductor, the proposed shield absorbs the electrical field lines efficiently without introducing excessive parasitic capacitance. Simulation results reveal that the proposed shield improves the quality factor of symmetrical inductors by 3.4% at 110GHz.Aiming at broadband RF front-end circuits, first of all, this thesis studies the broadband matching theory based on lossy transformer, which obtains the design equations of lossy matching network. This theory solves the gain ripple problem induced by transformer loss. On this basis, a differential broadband power amplifier (PA) is proposed. By carefully tuning matching networks and controlling their amplitude frequency response, the bandwidth of PA can be well controlled. Measurement results reveal that the proposed PA achieves small signal gain (S21) 3dB bandwidth of 23-39GHz and saturated output power (Psat) 1dB bandwidth of 23.8-38.1GHz. Besides, a broadband distributed power amplifier (DPA) is also proposed. Distributed structure is adopted to improve small signal bandwidth. Four transistors are stacked to improve gain and output power. Measurement results reveal that the proposed DPA achieves S21 3dB bandwidth of 2.0-15.4GHz with peak S21 of 19.4dB and peak Psat of 20.9dBm.Aiming at full-duplex RF front-end circuits, a 28GHz full-duplex RF front-end consisting of PA, low-noise amplifier (LNA) and electrically balanced duplexer (EBD) is proposed in this thesis. The hybrid transformer structure is adopted in EBD to provide isolation between PA and LNA and impedance matching simultaneously. Simulation results reveal that the proposed EBD achieves 38.6dB isolation at 28GHz, ensuring the normal operation of the full-duplex RF front-end. The proposed 28GHz full-duplex RF front-end achieves maximal Psat of 10.8dBm and minimal NF of 6.1dB.