以運算轉導放大器設計之電流式萬用二階濾波器電路之非理想分析與改進

Non-Ideal Effect And Improvement Of The Current-Mode OTA-C Universal Biquad Filter

劉侃茹(KAN-JU LIU)

指導教授 ： 張俊明

中原大學/工學院/電機工程研究所/碩士(2009年)

https://doi.org/10.6840/cycu200900770

摘要

在積體電路設計中，元件使用越多，所產生的寄生效應也會增加，研究如何使電路輸出信號精準一直是電路設計的目標。以往的設計中，被動元件浮接也會比起被動元件接地多出約一倍的寄生效應，因浮接被動元件所產生的等效寄生效應位置與電路中浮接被動元件位置不同，而使輸出信號失真。故如何簡化電路設計使元件使用數目降低，進而減少寄生效應且能兼顧輸出信號之精準度，實為現今一大研究目標。

本文所提出的二階電流式萬用主動濾波電路，為達簡化電路之目標，僅使用了兩個主動元件(OTA)，及兩個接地電容即達成電流式萬用濾波電路之功能，並利用分析合成法(Analytical Synthesis)之設計，所設計的電路同時符合三項OTA-C電路設計的準則：(1)使用單端輸入的OTA(以免除寄生電容的Feedthrough效應)，(2)使用接地電容(可直接吸收寄生電容)，(3)使用較過去為少的主被動元件(使得具有總體較低的寄生電容效應)符合這三項準則的電路，所有外加電容的位置剛恰與所有寄生電容的位置相同；進而此研究提出利用調整轉導值或外加電容值來吸收寄生電容，使電路在高頻能更精準。
本論文模擬部份以H-spice電腦軟體進行模擬，使用的製程參數為TSMC0.35 m，由擬結果和電路分析中可看出此電路之特性與優點。包括有：
（1） 使用最少的主動元件。
（2） 使用最少的被動元件。
（3） 電路中使用最少元件以達省錢，省能源，低雜訊，減少晶片面積等優點。
（4） 電路中電容均接地，以降低寄生效應。
（5） 電路具有優良之濾波效果。

關鍵字

電流式萬用二階濾波器電路 ； 運算轉導放大器

並列摘要

Abstract
In order to let the output signal to be accurate is always the circuit design goal.The more component used,the more parasitic effect resulted.Besides, floating passive components would cause more parasitic effect than grounded.Because the position of the parasitic effect caused by floating passive component is different from where the passive component.Hence,it would cause the output signal distortion.Nowadays,It is a big research aim at how to design to reduce components used on circuits.
In order to simplify circuits,this paper proposed a new current-mode universal biquadratic filter employing a dual active component (OTA) , two grounded capacitors and using “Analytical Synthesis Method” design. The “Analytical Synthesis Method” has been proposed to realize the high-order OTA-C circuits which achieving the following three important criteria simultaneously for the design of OTA-C filters: (i) using single-ended-input OTAs (overcoming the feedthrough effect due to the use of differential-input OTAs), (ii) using grounded capacitors (absorbing the shunt parasitic capacitance), and (iii) using the least number of component counts (reducing the total parasitic effects). Note that all the parasitic capacitances have the same places as those of all the given capacitors in the realized circuits achieving the above three important criteria. An improvement approach is then proposed by the absorption of parasitic capacitances from the given capacitors to obtain a precise high-frequency circuit.
The filtering performance of the new universal active current filter　 by the TSMC035 H-Spice simulation.The simulation result and the circuit analysis can verify that the circuit have the following adventages：
(i) The minimum active component is used.
(ii) The minimum passive component is used.
(iii) The minimum component result low cost,low power consumption,low noise,and small chip area.
(iv) All grounded capacitor would reduce the parasitic effect.
(v) The circuit results high filter performance.

並列關鍵字

OTA-C

參考文獻

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[2]C. M. Chang, and S. K. Pai, “Universal Current-Mode OTA-C Biquad with the Minimum Components”, IEEE Transactions on Circuits and Systems—I: Fundamental Theory and Applications, vol. 47, no. 8, pp.1037-1040, Aug. 2000.

[3]M. T. Abuelma'atti, and A. Bentrcia, ” New Universal Current-mode Multiple-Input Multiple-Output OTA-C Filter”, The 2004 IEEE Asia-Pacific Conference on Circuits and Systems,Tainan, Taiwan, pp.1037-1040, Dec. 2004.

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