0.8～2.5GHz CMOS超宽带低噪声放大器设计

发布时间：2018-08-26 20:50

【摘要】：随着现代通讯技术的发展,以往的窄带低速传输已经难以满足用户需求,宽带高速传输将是未来的主流趋势。超宽带技术以其高速、低功耗和低成本被视为未来宽带高速传输的主流技术之一。作为射频前端中的核心部分,超宽带低噪声放大器的性能决定着宽带系统的整体性能,因而研究并优化宽带CMOS低噪声放大器将具有重要意义。首先,本文分析比对了常见的几种宽带输入级结构,并在折衷考虑了有效带宽、元件数量以及传输效果的基础上设计出了三阶巴特沃斯高通滤波器作为输入匹配网络。其次,针对噪声和匹配之间的矛盾关系,本文摒弃在栅源之间并联电容的方法,改用电阻反馈加以解决,并研究了反馈元件对输入级的影响。然后,本文研究了直接匹配和源跟随器匹配两种输出方式在匹配、噪声和增益方面的特性。在此基础上提出了两级共源共栅结构的输出方式,以此缓解了初级增益压力。同时,为了少用大电感,本文采用并联峰化结构和串联至并联等效优化了二阶高通滤波器输出网络。此外,针对增益滚降,本文又提出了在级间内插电感,使其与栅源电容谐振抬高高频增益的解决方案,从而优化了高频端增益和增益平坦度。最后,采用TSMC 0.18μm RF CMOS工艺,在Spectre RF下对宽带LNA进行了仿真。仿真结果表明,在0.8~2.5GHz的工作频带内,LNA采用1.8V供电,输入输出匹配均小于-12dB,噪声系数小于3dB,增益大于16.5dB,增益带内波动在1.75d B以内,在1.6GHz处的三阶交调为-5.05dBm。
[Abstract]:With the development of modern communication technology, the narrow band low speed transmission has been difficult to meet the needs of users, broadband high-speed transmission will be the mainstream trend in the future. Ultra-wideband (UWB) technology is regarded as one of the mainstream technologies of broadband high-speed transmission in the future because of its high speed, low power consumption and low cost. As the core part of RF front-end, the performance of UWB LNA determines the overall performance of broadband system. Therefore, it is very important to study and optimize the Wideband CMOS LNA. Firstly, several common broadband input level structures are analyzed and compared, and a third-order Butterworth high-pass filter is designed as an input matching network on the basis of considering the effective bandwidth, the number of components and the transmission effect. Secondly, in view of the contradiction between noise and matching, the method of parallel capacitance between gate sources is abandoned, and resistive feedback is used to solve the problem, and the effect of feedback element on input stage is studied. Then, the characteristics of direct matching and source follower matching in matching, noise and gain are studied. On the basis of this, the output mode of two-stage common-gate structure is proposed to relieve the primary gain pressure. At the same time, in order to reduce the use of large inductance, the output network of second-order high-pass filter is optimized by using parallel peaking structure and series-parallel equivalent. In addition, for the gain rolling down, an interstage interpolation inductor is proposed to raise the high frequency gain by resonant with the gate source capacitance, thus the gain and flatness of the high frequency end are optimized. Finally, wideband LNA is simulated under Spectre RF using TSMC 0.18 渭 m RF CMOS process. The simulation results show that 1.8V power supply is used in the operating band of 0.8~2.5GHz, the input and output matching are less than -12dB, the noise coefficient is less than 3dB, the gain is more than 16.5 dB, the fluctuation in the gain band is less than 1.75dB, and the third-order intersection at 1.6GHz is -5.05dBm.
【学位授予单位】：上海交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN722.3

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