【作者】 张滨；

【导师】 杨银堂；

【作者基本信息】 西安电子科技大学 ， 微电子学与固体电子学， 2013， 博士

【摘要】 低噪声放大器(Low Noise Amplifier,LNA)作为接收机前端的重要组成部分,其增益、噪声系数和线性度等指标直接影响着接收机的接收性能和灵敏度。随着现代无线通信技术的发展,对数据传输速率和频带的要求也越来越高,因此对超宽带低噪声放大器的性能指标提出更高的要求。锗硅异质结双极型晶体管(Silicongermanium Heterojunction bipolar transistor, SiGe HBT)作为一种新型射频器件,具有与GaAs器件可媲美的噪声、增益和频率特性,并且与现有的Si工艺兼容,兼有高频、低功耗和低成本的优点,因此成为近年来的研究热点。本文对SiGe HBT电学性能和结构工艺参数、SiGe HBT噪声模型和SiGe HBT LNA电路进行了较为深入的研究。其主要的创新性成果有：(1)对SiGe HBT进行理论研究。分析讨论了半导体异质结的基本原理、SiGe HBT的直流特性和频率特性以及SiGe HBT的各种结构参数对晶体管性能的影响。分析结果表明异质结在噪声和频率特性等方面优于同质结,通过合理优化晶体管的结构参数能使晶体管得到最大电流密度和击穿电压,并具有足够高的电流增益和特征频率。建立了SiGe HBT结构和工艺参数与晶体管的增益、噪声和特征频率之间的关系,据此实现了晶体管的噪声、增益和特征频率的优化。(2)对双极型晶体管的Ebers-Moll模型、Gummel-Poon模型、SPICE模型以及噪声模型进行分析研究。研究结果表明,为使SiGe HBT电路噪声系数降低,应该基区高掺杂,发射区低掺杂,减小基区宽度,从而减少基区渡越时间以提高晶体管截止频率。建立了SiGe HBT简化SPICE噪声模型,得到了晶体管最小噪声系数与工作频率和集电极电流之间的关系,为电路设计提供参考依据。用ADS软件仿真出SiGe HBT的最小噪声系数与工作频率之间的关系。结果表明,双极型晶体管最小噪声系数随工作频率增大而呈现非线性增长。(3)讨论了低噪声放大器电路的各种指标参数以及常用的超宽带放大器的电路拓扑结构,并对低噪声放大器的偏置电路以及匹配理论进行理论分析。低噪声放大器的指标参数是设计的依据和目标。设计电路前首先要确定电路的拓扑结构,差分式放大器的噪声系数和成本比较高,平衡式放大器稳定性和线性度好,但是噪声不理想,负反馈式放大器稳定性高,牺牲增益换取更优异的增益平坦度。而偏置电路为晶体管提供合适的偏置电压和偏置电流。电感偏置电路噪声性能和线性度好,但其面积较大且带有损耗。电阻偏置电路相比电感偏置电路可以减少电路面积,但是在噪声和线性等参数方面不如电感偏置电路。双偏置电路在噪声、功率损耗、线性度等各方面参数表现最为出色。(4)基于JAZZ0.35μm SiGe工艺,采用ADS软件设计并仿真一个工作在3.1-10.6GHz的低噪声放大器。该低噪声放大器电路的输入极采用共发射极结构,利用发射极反馈电感来进行输入匹配,第二级采用达林顿结构对信号提供合适的增益。使用ADS2006软件进行设计、优化和仿真。仿真结果显示,在3.1-10.6GHz带宽内,放大器的电源电压在5V时,噪声系数低于3.3dB,增益大于25.1dB,输入输出回波损耗低于-10dB,输入输出驻波比小于1.9,功率损耗为32mW。整体电路的性能指标受器件的增益、噪声等特性和电路的设计影响。对器件而言,影响因素包括结构和工艺等因素；对电路而言,影响因素包括电路拓扑结构、偏置电路、匹配电路等。本文首先对SiGe HBT模型和噪声理论进行分析研究,为电路设计提供理论指导。然后对SiGe HBT LNA电路进行理论分析,并仿真了一款应用在UWB频段内的LNA电路。本文为SiGe HBT LNA电路设计提供重要的理论指导和设计思路。更多还原

【Abstract】 As an important component of receiver front-end, low noise amplifier plays an critical role in the whole system while the performance of its gain, noise figure and linearity is closely related to the receiver’s performance and sensitivity. The fast development of modern wireless communication technology, demands faster data transmission rate and larger band-width, and the performance of Ultra-wide band LNA need to be improved constantly.As a new category of radio-frequency device, the SiGe Hetero junction bipolar transistors are gradually used in the circuit design of LNA, which is with almost the same performance as a GaAs one in gain, noise feature and frequency performance. The SiGe device is compatible with current Si processes, and has excellent characteristics of larger band-width, lower power consumption and cost.Both the electrical properties and noise feature of SiGe HBT and the Low Noise amplifier of SiGe HBT circuit are analyzed and discussed in this thesis. The main job includes:(1) A theoretical analysis of SiGe HBT device is studied. With a review into the fundamental principles of hetero-j unction, the DC-performance and frequency performance, the relationship between multiple SiGe HBT device structure parameters and the transistor performance are analyzed and discussed. The results indicate that HBT has uniquely excellent noise and frequency performance in comparison with traditional bi-polar junction transistor. In this case, the frequency performance and the noise feature of transistor could be significantly improved with a reasonable optimized design of transistor structure parameters. Meanwhile, and the device has maximized current density and breakdown voltage, as well as enough current gain and characteristic frequency.(2) A deep research into the multiple HBT models is carried out in the second chapter, such as the Ebers-Moll model, the Grammel-Poon model, the SPICE model and the noise model. The results reveal that higher dopant concentration in the base-area and lower dopant concentration in the emitter-area lead to lower noise figure of the SiGe HBT circuit. Meanwhile, smaller base-area width which means shorter transit time could improve the transistor’s cut-off frequency and parasitic resistance.The following simulation of SiGe HBT device based on ADS software reveals that the minimum noise figure is non-linearly increasing with the increasing input working frequency. (3) An introduction is made including the multiple parameters of Low Noise amplifier circuit, and a theoretical analysis into the bias circuit and matching problem. The indicator parameter is both the foundation and goal of Low Noise amplifier circuit design, of which the first step is to choose topological structure. Balanced amplifier enjoys good stationary and linearity, yet ideal noise figure; negative feedback amplifier enjoys high stationary and more excellent gain flatness in cost of gain itself. The bias circuit provides both suitable biased-voltage and biased-current for transistor. Inductance bias circuit is characterized by good noise performance and linearity yet large circuit area and additional waste of power; resistance bias circuit out-performs the former in circuit area, but loses in noise feature and linearity. The mixed bias circuit bears the most excellent performance in noise feature, power consumption and linearity.(4) A Low Noise amplifier is designed based on JAZZ0.35um SiGe processing technology and simulated based on ADS software with the working frequency spanning between3.1-10.6GHz. The common-emitter structure is used in input stage design, with emitter series feedback inductance for input matching. The Darling structure is used in secondary stage design to provide suitable gain for input signal. Finally, a series of task including designing, optimizing and simulating is carried out based on the software of ADS2006. Results show noise figure of the amplifier is below3.3dB with working voltage of5V in3.1-10.6GHz, gain greater than25.1dB, Noise figure below3.3dB, S11and S22below-lOdB, VSWRin and VSWRout below1.9, and power consumptions32mW.The performance of overall circuit is affected by the gain of the device performance, noise characteristics and the design of circuit. For the device, the influencing factors include the structure and process and other factors. For the circuit, the impact of factors include the circuit topology, the bias circuit, and the matching circuit. SiGe HBT model and noise theory analysis are studied in this thesis to provide theoretical guidance for the circuit design. Then analysis and simulation of an application in the UWB frequency band LNA circuit by the theoretical of SiGe HBT LNA circuit are carried out. This thesis may provide theoretic guide for the design of SiGe HBT LNA circuit.更多还原