MEMS在线式宽带大功率微波鉴相器的研究

With the development of radar and communications, the existing microwave phase detectors can no longer meet the increasing demands for their defects in narrow bandwidth, low power capacity and incapability of detecting power unknown signals. This program proposes and studies a MEMS in-line type wideband large signal microwave phase detector based on vector combination and MEMS microwave power detection technology, phase-power-voltage conversion is realized in the phase detector and the phase is eventually tested as an output voltage. The emphases of this program lie on the implementation of wideband property and in-line type large power signal detection ability. The presented phase detector consists of a wideband power combiner that can detect the input power and an in-line type combined power detector. Wideband property is realized through dual-section impedance transformer. Cascaded structure of MIM capacitor and thermoelectric MEMS power sensor is applied to accomplish in-line type power detection. The -15dB relative bandwidth over X-band is aimed to be 40% and the dynamic range is aimed to be 0~2W. This phase detector consumes none dc power and is easy to be compatible with GaAs MMIC process. Moreover, it is featured by wide bandwidth and high power capacity, anti-burn ability and reliability. This program is aimed to obtain innovation achievements in the key techniques of theory, design, fabrication and test of the presented phase detector and lay the foundation for its application in radar and communication systems.

随着雷达及通信领域的发展，频带窄、功率容量小以及无法检测功率未知信号等因素使现有的鉴相器愈发无法满足日益提高的应用需求。本项目提出并研究一种基于矢量合成原理与MEMS微波功率检测技术的MEMS在线式宽带大功率微波鉴相器，实现相位−功率−电压的间接测量，重点研究其宽带技术及大功率信号检测技术，在结构上集成了具有功率测量能力的宽带功合器及在线式合成功率检测器，通过双节阻抗变换器实现宽带设计，通过MIM耦合电容与热电式MEMS微波功率传感器级联实现在线式大功率测量。目标频段X波段内，回波损耗-15dB相对带宽达40%，动态范围达0~2W。该鉴相器无直流功耗，与GaAs MMIC制备工艺兼容，具有较高的带宽、功率容量、抗烧毁水平及可靠性，还能对功率未知信号进行鉴相。本项目力争在MEMS宽带大功率微波鉴相器的理论设计、制备测试等关键技术方面取得创新成果，为其在雷达、通信领域的应用奠定理论与技术基础。

针对现有通信系统中宽带高功率信号检测技术需求，为解决现有微波鉴相器工作频带窄、功率容量小、线性度较差等问题，本项目研究并设计了一种基于矢量合成原理与MEMS微波功率检测技术的MEMS宽带大功率微波鉴相器，在宽带、大功率范围内实现相位−功率−电压/电容的转换与测量。这种鉴相器无需直流功耗，与GaAs MMIC制备工艺兼容，具有较高的带宽、功率容量、线性范围、抗烧毁水平等。项目研究中，通过双节阻抗变换器实现宽带设计，通过MEMS梁耦合电容与热电式MEMS微波功率传感器级联实现在线式大功率测量；在此基础上分别实现了终端式、在线式、以及混合式RF MEMS鉴相器的设计与优化，并利用GaAs MMIC工艺实现了样件的加工制备。测试结果表明上述三种结构均工作在X波段，相位检测范围为0-180°。此外，终端式结构动态范围10-200mW，线性范围10-200mW；在线式结构动态范围200-2000mW，线性检测范围250-1400mW；混合式结构动态范围200-1600mW，线性检测范围200-1600mW。与已有文献对比，本项目提出的鉴相器动态范围和线性检测范围大大提升，有望应用于射频微波前端电路、频率和成系统和相控阵系统等。