| 摘要: | 近年來，極端氣候頻繁地發生，強降雨時常導致災害。為能對天災及早預防，保障人們的生命與財產，天氣預測愈來愈重要。要增進降雨預測的準確度、建立可靠的氣候模型供數值模擬使用，對雲層的觀測是不可或缺的。若能在尚未變成降雨前就對雲層的範圍及內部構造有所掌握，可讓我們在災害發生前有更多的防災準備時間。雲雷達是觀測雲層內部構造及動向的利器。相較於被動式的輻射計，主動式的雷達可以透過發射高功率的訊號，穿透較厚的雲層，得到較深入的觀測資料。若雲雷達的毫米波前端採用主動式相位陣列的架構，除了波束掃瞄將可以快速的電子式掃描來進行，亦可將發射器化整為零，將輸出功率的負擔分散到每個天線前的功率放大器上。如此，整個雲雷達系統將可以solid-state方式來實現，而這也是本計畫的出發點。本研究計畫「應用於主動式相位陣列雲雷達之毫米波前端電路」之目的為開發適用於35 GHz主動式相位陣列雲雷達的關鍵電路，包括天線、收發開關、功率放大器、相位偏移器及功率分配器。功率放大器、收發開關及on-chip天線將以GaAs pHEMT製程來實現，而相位偏移器（被動式）及功率分配器則以CMOS製程實現。GaAs晶片與CMOS晶片則將以覆晶鍵合的方式連接並堆疊起來，以達到高整合度的效果。本研究計畫預計以一年的時間來完成。前期的重點在於電路與天線設計；中期的重點量測設置的準備；後期的重點則是晶片與模組的量測。本計畫之成果預計將以一個應用於雲雷達的35-GHz之2×1相位陣列晶片模組來呈現。 ;In recent years, extreme weather and climate events occur much more frequently than before. Extreme heavy rain often causes disasters. To prevent the natural disasters in advance and in time, saving people’s lives and properties, weather prediction plays a more and more important role. To improve the accuracy of rainfall prediction and build reliable climate models for numerical simulations, it is essential to observe the clouds. If we can acquire information on the boundary and inner structures of clouds before they become rains, it would give us more time to prepare for the extreme weather and avoid the disaster it causes. Cloud radars are valuable tools for looking into the clouds and understanding their dynamics. Compared to the passive radiometers, in-depth observation data can be obtained by using the active radars, which actively transmit high-power signal that is able to penetrate thick cloud layers. If one adopts the active phased array (APA) architecture for the millimeter-wave front-end of the cloud radar, not only the beam scanning can be done electronically with fast speed, but the loading of generating high transmit power is distributed to the power amplifier in each antenna element rather than being put on one big transmitter. As such, the whole cloud radar system may be realized in solid-state form, which is the basis of the proposed project. The proposed project “Millimeter-Wave Front-End Circuits for Active Phased-Array Cloud Radars” is aimed at developing key circuits, including antenna, T/R switch, power amplifier, phase shifter, and power divider, for 35-GHz APA cloud radars. The power amplifier, T/R switch, and on-chip antenna will be implemented using a GaAs pHEMT process, whereas the passive phase shifter and power divider will be realized using a Si CMOS process. The GaAs chips and CMOS chip will be stacked and connected together by flip-chip bonding so that the module is highly integrated. We plan to complete this project in one year of time. The focus for the early stage will be circuit and antenna design. In the medium term of the project period, we need to prepare the measurement setup. When the time is near the end, we will measure and test the chips and the module. A highly-integrated 35-GHz 2×1 phased array chip module will be presented when the project is completed to summarize the research and development efforts. |
