應用於現代通訊系統之鏡像抑制電路與自動增益控制電路之研究

Abstract

本論文的主題在於使用台積電0.25um標準金氧半製程，分別實現一具寬頻特性的鏡像抑制電路與一自動增益控制電路。前者應用於數位電視選台器系統中，後者使用於同步光纖網路系統中。 所實現的鏡像抑制電路，是在Hartley架構的基礎上，改採用串接多級的多相位濾波器來克服其窄頻九十度相位移的問題。量測結果顯示在所欲工作的6 MHz訊號頻寬內皆有大於25dB的鏡像抑制量，整體電路可產生11dB的增益，1dB壓縮點落在-12dBm，OIP3則為48dBmV。 而所實現的自動增益控制電路，包含了可變增益放大器、寬頻放大器、震幅檢測器與一積分器。並採用迴授式架構以降低對製程飄移的敏感度。此電路已經由台積電0.25um 1P5M CMOS製程製作，整體晶片面積為 ，在包含輸出級的情況下，共消耗66mW。

The goal of this work is to use TSMC 0.25um standard CMOS process to implement one wideband image-reject circuit and one automatic gain control circuit. The former is for Digital TV tuner system, and the latter is for Synchronous Optical Network system. The image reject circuit is on the basis of Hartley Architecture, and the cascaded polyphase filter is used to overcome the narrowband phase shifter. The measurement results show more than 25dB IRR in the wanted 6 MHz bandwidth. The whole chip can provide 1dB gain, -12dBm P1dB, and 48dBmV OIP3. The automatic gain control circuit includes variable gain amplifier, wideband amplifier, amplitude detector, and integrator. Feedback type AGC is adopted for reducing the sensitivity to process variation. The circuit is fabricated by TSMC 0.25um 1P5M technology. The chip size is , and the circuit including output buffers consumes 66mW.