| 摘要: | 本計畫提出應用於THz影像系統之高效能THz發射機，用來將Chirp電路所提供的訊號進行放大及升頻，產生THz頻率調變連續波訊號。發射機晶片採用28-nm CMOS製程實現。計畫前二年規劃整合功率放大器、頻率倍頻器、功率分配網路及功率合成網路，利用功率合成技術，將四個發射電路之輸出功率進行疊加，實現高輸出功率發射機，可提供0 dBm輸出功率、0.5%功率轉換效率及頻寬為32 GHz之320~352 GHz頻率調變連續波訊號。此高輸出功率發射機將整合其它子計畫所負責之電路，完成機械式掃描THz影像雷達系統之設計，可於25公尺遠，對50 cm×100 cm面積，提供1 cm距離解析度、1.9 cm橫向距離解析度及2 fps影像更新速率之影像性能。計畫後二年規劃整合功率放大器、頻率倍頻器、功率分配網路、可變增益放大器、相位偏移電路、升頻混頻器、鎖相迴路，採用IF相位偏移相位陣列技術，實現4×4 THz相位陣列發射機，可提供0 dBm輸出功率、0.5%功率轉換效率、數位控制±30°輸出波束掃描角度範圍、1°掃描角度解析度及頻寬為32 GHz之320~352 GHz頻率調變連續波訊號。當整合其它子計畫之電路，這個可數位控制波束掃描方向之THz發射機，可取代旋轉平面鏡，實現電子式掃描即時THz影像雷達系統，解決傳統機械式掃描速度過慢等問題，影像更新速率可提升至20 fps。 ;High-performance THz transmitters are proposed in this project for THz imaging applications. The transmitters realized in a 28-nm CMOS technology are employed to amplify and frequency multiply the signal provided by a chirp generator to generate a THz frequency-modulated continuous-wave (FMCW) signal. For the first- and second-year project, the transmitter is planned to be composed of power amplifiers, frequency doublers, a power dividing network, and a power combining network. A power combining technique is conducted to combine the output power from four transmitter circuits to enhance the transmitter output power. By doing this, the transmitter can provide an FMCW signal with output power of 0 dBm, dc-to-RF conversion efficiency of 0.5%, and 32-GHz bandwidth. This high output power transmitter will be integrated with the circuits designed by other sub-projects to realize a mechanical scanning THz imaging radar system which can exhibit range resolution of 1 cm, cross-range resolution of 1.9 cm, and a frame rate of 2 fps for taking an image with an area of 50 cm×100 cm at 25 m standoff distance. For the third- and fourth-year project, the transmitter is planned to be consisted of power amplifiers, frequency doublers, a power dividing network, variable-gain amplifiers, phase shifters, and phase-locked loops. An IF phase shifting architecture is chosen to realize a 4×4 THz phased-array transmitter which can provide an FMCW signal with output power of 0 dBm, dc-to-RF conversion efficiency of 0.5%, digitally-controlled beam-steering angle of ±30°, and beam-steering angle resolution of 1°, and 30-GHz bandwidth. The phased-array THz transmitter can replace the rotating mirror used in a mechanical scanning THz imaging system to solve the issue of slow scanning speed. This phased-array THz transmitter will be integrated with the circuits designed by other sub-projects to implement an electronic scanning real-time THz imaging system with a frame rate up to 20 fps. |
