運算轉導放大器與電流追隨器之研究

The Research of Operational Transconductance Amplifier and Current Follower

楊昆穎(Kun-Yin Yang)

指導教授 ： 侯俊禮

中原大學/工學院/電子工程研究所/碩士(2003年)

https://doi.org/10.6840/cycu200300232

摘要

本篇論文有兩個研究重點：第三章的電流式與電壓式OTA電路之轉換法，第四章的低電壓CMOS AB類電流式追隨器。
在第三章中，我們把運算轉導放大器（OTA）所構成之電壓式電路，經由簡易且可預測之伴隨轉換法來進行轉換，以得到預期之電流式電路，其電壓式OTA電路轉移函數將等於電流式OTA電路轉移函數，反之，電流式OTA電路轉換成電壓式OTA電路亦然。此伴隨轉換法相當簡易，在轉換時，主動元件僅需BOTA與OTA兩種，被動元件完全不需改變，電路架構也不會有太多更動。這是此轉換法最大的優點。
而第四章中，提出一種新型低電壓AB類CMOS電流追隨器，是針對目前電路架構缺點來進行改善。此電路主要的優點為大輸入電流與高操作頻寬且工作電壓為 ，此外，正型與負型電流追隨器的輸入電阻值約為4Kohms，而其輸出電阻值約為100Kohms，輸入電流範圍從-400uA到400uA。正型電流追隨器的頻寬約為225MHz，負型電流追隨器為158MHz，正型電流追隨器的諧波失真為2.38％，負型電流追隨器則為2.39％。本電路的特性，較先前之電路有長足之進步，使得本電路在應用上受到更少限制，間接的也使得系統的特性上升。因此發展更高效能的電路系統也較為可行。

關鍵字

伴隨轉換法 ； 轉導放大器 ； 電流追隨器 ； 電流式

並列摘要

There are two emphases in this thesis: the transformation of voltage-mode to current-mode OTA circuit in chapter 3 and low voltage CMOS class AB current follower in chapter 4.
In chapter 3, we use a simple and predictable adjoint transformation to transfer the voltage-mode OTA circuit into current-mode one that we anticipated. The transfer function of the voltage-mode OTA circuit will be identical to that of the current-mode OTA circuit and vice versa. This adjoint transformation is very simple. When transfer, we need only BOTA and OTA as active elements and passive elements need no change at all. Also, the circuit structure will be slightly changed; it is the major advantage of this transformation.
Alternatively, a new low voltage class AB current follower is presented in chapter 4. It’s the improvement in accordance with defects of the circuit structure at present. The main merits of this circuit are large input current and wide operating bandwidth and operating voltage. Moreover, the input resistances of both positive- and negative-type current followers are 4Kohms, and the output resistances are about 100Kohms. The input current range is -400uA to 400uA. The bandwidth of the positive current follower is about 225MHz while that of the negative one is 158MHz, and the harmonic distortion of the positive current follower is about 2.38% while that of the negative one is 2.39%. The characteristics of the circuit exhibit larger progress than the circuits proposed in the past. So that the circuit has less limitations in applications and the characteristics of the circuit are indirectly improved. Thus, it is more practicable to develop the circuit system with high efficiency.

並列關鍵字

adjoint-transformation ； current-mode ； OTA ； current follower

參考文獻

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[2] K. C. Smith, and A. Sedra, ” the current conveyors – A new circuit building block “ , Proceedings of the IEEE, 1968, pp. 1368-1369.

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[4] A. Piovaccari,“ CMOS integrated third-generation current conveyor “ Electronics Letters, 1995, vol.31 pp. 1228-1229.

[5] A. S. Sedra, G. W . Roberts, and F. Gohh, “ The current conveyor : history, progress and new results “, IEE Proc. G,1990, vol.137,pp.78-87.