一種可量產的GM-C濾波器設計方法

Abstract

本論文第一章中，首先描述中頻濾波器於通訊系統所扮演的角色, 其次論及為何以 GM-C 濾波器為主題, 接著說明本論文的研究動機及研究方法。第二章中，先針對GM-C濾波器的基本原理及功能方塊先作介紹，而後，討論固定及變動誤差之可補償性。第三章以36 MHz中頻帶通濾波器作參考設計，研究 IC 的 Corner 效應與溫度效應,分析並證明此帶通濾波器可用 IC trimming 和自補償偏壓電路完成前面兩種變異的補償。 第四章總結出以下結論: 使用 IC trimming 消去因製程造成的變異，再利用自補償偏壓電路以補償 IC 的溫度效應. 由分析結果可證明其可行性，但因為不具有自動錯誤反饋系統，故存在某範圍內的誤差。此一誤差限制了本文所提出的濾波器使用範圍，但在 Low-Q 濾波器應用上具有多方面的優點。根據本文所提出設計方法所設計的 GM-C 濾波器，具有電路簡單，佔用極小 IC 面積，耗電低，及應用頻率廣的優點。且因不需要於電路工作中同時調校，而有信號易受干擾的問題。除此因不需精準參考振盪頻率源作電路自動調校，故可用於無參考振盪頻率源的通信系統中。但因為需要使用到 IC Trimming 技術，故會增加 IC 的測試成本。其中， IC Tester 端的濾波器中心頻率錯誤檢測系統的設計優劣會大幅度的影響測試時間，進而影響 IC 的測試成本。 本文所提出的 GM-C 濾波器設計方法, 係提供另一種濾波器設計的可能性，論述中的許多環節仍有很大的研究空間。但本文詳述筆者的研究動機，根據理論，接著分析 GM-C 濾波器的 Corner 和溫度效應，最後，證明採用此設計方法可應用於 Low-Q 中頻濾波器中。全文重點乃是試圖為中頻濾波器的設計方法擴展更大的思考空間。

In Chapter 1, there are some descriptions about the role of the IF filter in a communication system. Then, the motivation and the methodology to perform the research of the GM-C filter is presented. In Chapter 2, the fundamental theorem and functional blocks of the GM-C filter are introduced. After that, the possibility to compensate the fixed and variable errors is discussed. In Chapter 3, the author uses one 36MHz IF band-pass filter as reference design to study the corner effects and the temperature effects. Analyses and proves that the two variances of this filter can be compensated by using IC trimming skills and self-compensated bias circuits. In Chapter4, it is concluded that one can use the IC trimming skills to correct the center frequency error of the band-pass filter that is due to the IC process variance, and then use a self-compensation bias circuit to compensate the IC temperature effect. This design methodology is approved in this thesis, but a small error will exist due to the fact that this method is not an auto-feedback system, such as the auto-tuning method. This error will limit the application of the IF filter, but there are still lots of benefits in the low-Q IF filter design. The GM-C filter that is designed by this suggested methodology has a lot of benefits. These benefits are a) simple design method, b) very small IC area, c) low power consumption, d) no interference that exists in the auto-tuning system, and e) no need of an accurate reference frequency source. This method uses the IC trimming technology in the IC test, so the test cost will be increased. The center frequency detection system of band-pass filter will dominate the total test time in the IC tester. To design an excellent center frequency detection system will reduce the IC test cost. The purpose of the GM-C filter design methodology that is presented in this thesis provides another design possibility for GM-C filter mass production. There are some research areas that can be done following this design methodology. The research motivation and the theorems are introduced. The corner effect and temperature effect of the GM-C filter are then analyzed. Finally, this design methodology can be proved to be useful in low-Q IF filter design. The key point of this thesis is to provide an alternative for the mass production of IF band-pass filter design.