24GHz連續調頻雷達接收機模組之設計

Abstract

本論文提出一24 GHz之雷達接收機之模組，應用於盲點偵測系統。論文中提供了一個完整的接收路徑，包含一雙級低雜訊放大器，帶通濾波器以及次諧波混頻器。其中低雜訊放大器是使用市場上常見的高頻場效電晶體，其具有低雜訊指數、低價格，可操作於高頻等優點，但由於此電晶體的應用頻率僅到18 GHz，因此我們先量測該電晶體在特定偏壓之下於24 GHz時的表現並和模擬結果比較，分析其高頻寄生效應以萃取其高頻模型並使用其來進行模擬。放大器中使用了指叉式(Inter-digital)的共平面結構來匹配，其具有方便製造及節省成本等優點，完成的低雜訊放大器在增益和雜訊指數部分都有不錯的表現。接著下一級的帶通濾波器可確保進入後端混頻器的訊號頻率落在24 GHz附近，此濾波器是使用髮夾式(Hairpin)的架構，設計有三個共振點。最後的次諧波混頻器可有效減半壓控振盪器的頻率，大幅降低至做成本與提升成功率。整體的接收機模組具有低成本，製作容易之優點。

In this Thesis, a 24 GHz RADAR receiver module is presented, it is used in blind spot detecting system. In this work, a complete receiving path is presented, including two-stage low noise amplifiers, band-pass filters and sub-harmonic mixers. This module uses high-frequency transistors commonly used by RF front-end manufacturer, it has advantages such as low noise, low price. The data sheet only provides the performance data of the transistor under 18GHz, hence we build the high frequency model under specific bias voltage, and compare the measurement results with simulation ones, to analyze the high frequency parasitic effects of the transistor at 24 GHz. Then we use this well-established model to complete the design of the low noise amplifier. In the circuit design. we use the inter-digital co-planer structure for impedance matching .Then next stage, the hairpin microstrip band-pass filter can insure the frequency of the signal entering the mixers to be near 24 GHz. In addition, sub-harmonic mixer halve the frequency of the local oscillator. The total receiving module have the advantages of lower cost and easy to produce.