- 學位論文
使用可調式主動元件及接地電容設計之低通、高通、帶通濾波電路
Design of the Low-pass、High-pass and Band-pass Filter Structures using Adjustable Active elements and a Single Grounded Capacitor
摘要
由於運算轉導放大器(Operational Transconductance Amplifier,簡稱OTA)等效於一個主動元件及一個電阻器，使得所設計的電路(i)無需使用電阻器，大幅減少積體電路的製作面積；(ii)其電阻值可藉由偏壓電流的精確調整改變，使得以運算轉導放大器(OTA)及電容器(Capacitors，簡稱C)設計類比電路成為一個好的研究方向。 當前積體電路(IC)的製作技術無法將電容器製作得很精準，使得電路的輸出訊號產生相當大的誤差，這是目前IC製作上的嚴重問題。所以尋求可調元件來取代電容器以實現轉移函數中S項的作用，成為一個重要的研究方向。過去經常被使用的運算放大器(Operational Amplifier；簡稱OA)其輸出輸入的關係如下： 式中的 為增益大小， 為頻帶寬， 為增益及頻帶寬的乘積。由上式可知，運算放大器也可以實現轉移函數中S項的作用。 運算轉導放大器中的轉導值(其倒數即為一個等效電阻)一樣可否藉由改變偏壓電流而改變大小呢？經過本論文研究結果，吾人發現：運算放大器的 值的確可藉由偏壓電流及其內部補償電容的調整而改變。這一個發現找到了替代電容器而可以調整大小的元件，也就是可調的運算放大器。 在本論文提出使用可調式主動元件及接地電容器設計濾波電路，在不需改變任何電路結構的情形下，皆可實現低通、帶通、高通三種濾波信號。一般的OTA-C二階電路至少都有兩個電容器，本論文將其中一個電容器換成具有可調整性的運算放大器，而這可調的運算放大器可解決電容器無法製作精準的問題。利用正規化及逆正規化的計算消除OTA-C電路因IC製程關係電容器製作受限於技術的門檻，無法做到百分之百精準的問題。將電路參數設計成可調模式，增加電路的整體調整性。為了使電路有很好的準確性，所以依照 Butterworth 法則，並且以敏感度的數學計算式與實際模擬結果做驗證以達成效。 對本論文所提出的電路做實際的驗證。在模擬方面利用Hspice 進行電路特性模擬，使用tsmc035參數來進行製程模擬的驗證，並利用Matlab 得到的理想結果進行濾波性能（Filtering performance）、相關特性比較與驗證探討並紀錄方式和數據作為以後研究非理想效應之參考資料。
並列摘要
It is worthy of research to do the analogue circuit design using Operational Transconductance Amplifiers (OTAs) and Capacitors (Cs) because an OTA is equivalent to both an active element and a resistor leading to a more condensed integrated circuit without resistors ,and because the equivalent resistor value can be electronically tuned varying the bias current. Due to the difficulty to precisely fabricate the capacitance in integrated circuits, it becomes an important research work to find a tunable element for the replacement of the capacitor used to realize the s terms in transfer functions. The input-and-output relationship of an Operational Amplifier (OA) is shown as below.in which is the gain, the bandwidth , and the product of both gain and bandwidth . It is exhibited that, an OA can also be used to realize the s terms in transfer functions. Hence, is the variable . In this thesis , we have found that the is variable tuning either the bias current or the inner compensation Capacitance of an OA just like the variation of the trancondance of an OTA through the tuning of its bias current. Therefore, the capacitor with error fabricated in the integrated circuits can be replaced by the OA tunable through its inner bias current. In the thesis, we proposed the Structures using Adjustable Active elements and a Single Grounded Capacitor.In is not change any circuit situation of structure to need, can realize Low-pass、High-pass and Band-pass Filter Structures, three kinds filters.General OTA-C two stepses of circuit are all two electric capacities at least, in the thesis a condenser among them changes into having adjustable OA, and this adjustable OA can solve the problem that the electric capacity is unable to make perfectly .It is worthy of research to do the analogue circuit design using Operational Transconductance Amplifiers (OTAs) and Capacitors (Cs) because an OTA is equivalent to both an active element and a resistor leading to a more condensed integrated circuit without resistors ,and because the equivalent resistor value can be electronically tuned varying the bias current. In order to make the circuit have very good accuracy, so according to Butterworth rule, and prove with the actual simulation result in order to reach the result with the mathematical measurement type of the susceptibility. Do real verification to this circuit put forward of thesis. Utilize Hspice carry on circuit characteristic simulation in imitating , use tsmc035 parameter make verification of simulation Cheng to go on to come, utilize the ideal result that Matlab receives to strain wave performance (Filtering performance), the relevant characteristic compare with proving not probing into and not noting down by way and data as after study by reference material of effect not ideal non-.