以電流式主動元件設計之微分器與震盪器

Design of Differentiator and Oscillator Employing Active Current-Mode Elements

陳光遠(Guang-Yuan Chen)

指導教授 ： 洪君維

中原大學/工學院/電子工程研究所/碩士(2003年)

https://doi.org/10.6840/cycu200300150

摘要

摘要

本論文主要是使用電流回授放大器（Current Feedback Amplifier；CFA）來設計一個電容器接地之非反相微分器（Non-Inverting Differentiator）；以及使用單增益元件（Unity-Gain Cell）做為主動元件，設計出一個正交震盪器（Quadrature Oscillator）。

首先，我們提出一個以單一電流回授放大器（CFA）、五個電阻器和一個接地電容器所合成的非反相微分器。此電路擁有以下的特點：(1) 較小的時間常數（Time Constant）可由單一接地電阻器來調整；(2) 只使用接地電容器，所以利於積體化的實現；(3) 因為CFA的輸出電阻很小，所以此微分器的輸出端可以直接和下一級電路做連接。

其次，我們提出一個以單一電流隨耦器（CF）、三個電壓隨耦器（VFs）、三個電阻器和三個接地電容器所合成的正交震盪器。此電路擁有以下的特點：(1) 因為電流隨耦器（CF）無電壓追蹤誤差，電壓隨耦器（VF）無電流追蹤誤差，所以設計出來的震盪頻率較為準確；(2) 震盪條件與震盪頻率互為正交可調；(3) 有很小的輸出電阻；(4) 主動與被動元件的靈敏度均很低；(5) 只使用接地電容器，所以利於積體化的實現。

最後，我們從實驗的結果證明本論文所提出之電路的可行性。

關鍵字

電流回授放大器 ； 正交震盪器 ； 單增益元件 ； 微分器

並列摘要

Abstract

In this thesis, a new non-inverting RC active differentiator network and a new quadrature oscillator using unity-gain cells are presented.

First, we present a non-inverting differentiator using one current feedback amplifier (CFA), five resistors and one grounded capacitor. This circuit provides the following advantages: (1) small time constant can be achieved by adjusting a single grounded resistor; (2) the use of only grounded capacitor that is ideal for integrated circuit implementation; (3) because the output impedance of the CFA is very low, the output terminals of the proposed circuit can be directly connected to the next stage.

Secondly, we present a quadrature oscillator using one unity-gain current follower (CF), three unity-gain voltage followers (VFs), three resistors and three grounded capacitors. This circuit provides the following advantages: (1) the tracking errors of the unity-gain cells have no effects on the oscillation frequency; (2) the oscillation condition and oscillation frequency are orthogonal controllable; (3) it has low output impedance; (4) the active and passive sensitivities are low; (5) the use of only grounded capacitors that is ideal for integrated circuit implementation.

In the end, experimental results are given to demonstrate the feasibility of the proposed circuits.

並列關鍵字

Unity-Gain Cell ； Quadrature Oscillator ； Current Feedback Amplifier ； Differentiator

參考文獻

[1] K. C. Smith, and A. Sedra, ”The current conveyor: a new circuit building block,” IEEE Proc., Vol. 56, pp. 1368-1369, 1968.

[2] A. Sedra, and K. C. Smith, ”A second-generation current conveyor and its applications,” IEEE Transactions on Circuit Theory, Vol. CT-17, pp. 132-134, 1970.

[3] A. Fabra, ”Insensitive voltage-mode and current-mode filters from commercially available transimpedance opamps,” IEE Proceedings-G, Vol. 140, No. 5, pp. 319-321, 1993.

[4] M. Higashimura, and Y. Fukui, ”Simulation of lossless floating inductance using two current conveyors and an operational transconductance amplifier,” International Journal of Electronics, Vol. 66, No. 4, pp. 633-638, 1989.

[5] G. W. Roberts, and A. S. Sedra, ”All current-mode frequency selective circuits,” Electronics Letters, Vol. 25, No. 12, pp. 759-761, 1989.