只使用參數可調式主動元件設計之低通、帶通及高通濾波電路

Design of the Low-pass、Band-pass and high-pass Filter Structures using Adjustable Active elements

戴詠軒(Yung-hsen Tai)

指導教授 ： 張俊明

中原大學/工學院/電機工程研究所/碩士(2006年)

https://doi.org/10.6840/cycu200600221

摘要

在傳統的濾波電路設計領域中，運算轉導放大器可等效為一個主動元件加上一個電阻，因此在以運算轉導放大器為主的設計電路中，電阻可被運算轉導放大器取代，而使得電路結構大大簡化。
運算轉導放大器可由改變偏壓電流去調整其轉導值，這解決電阻元件無法製造精確，進而造成訊號輸出的誤差，所以OTA-C所設計的電路，近年來在國際期刊中大量被發表。但相對的在電容製造上也存在著相同的問題，因此電容在元件製作上的不準確，而造成輸出訊號的誤差，這是設計濾波電路在積體化過程中面臨的重大的問題。
本論文研究當中發現過去長久以來被大家所使用的主動元件運算放大器其輸出及輸入的關係如下:

上式中頻帶寬( )與增益( )之乘積(B0)，可藉由運算放大器內部偏壓電流(Ibias)與補償電容(Cc)的關係，來改變其大小值，由此可得運算放大器是具有可調整性的特性。
所以本論文利用可調運算放大器來設計電路，其電路架構為單電壓、電流輸入以及三電壓輸出，經適當的輸入與輸出選擇，在輸出端可實現低通(Low-pass；LP)、帶通(Band-pass；BP)和高通(High-pass；HP)等三種濾波器功能。
本論文所提出的電路均以HSPICE做為實際驗證的模擬工具，以TSMC035的製程參數做為在晶片化前的考量參數。本論文以Matlab作理論值的驗證，HSPICE所模擬的結果與理論值有相當的吻合，因此本論文設計的電路，未來在實際的運用上有很大的發展性。

關鍵字

類比式低通 ； 帶通及高通濾波電路

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, the question is：“Is the variable , as he transconductance of an OTA , or not” ? 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.
The thesis is focused on he design of biquads using both tunable OAs and tunable OTAs ，leading to very precise output responses such as lowpass bandpass and highpass filtering signals . Finally, the H-spice simulation with TSMC035 process verifies the theoretical predictions.

並列關鍵字

Design of the Low-pass ； Band-pass and high-pass Filter Structures

參考文獻

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