以運算轉阻放大器為主動元件實現五個電壓式四階橢圓濾波電路之方法與其性能之比較

以往學者多用OTA為主動元件去設計電路，而OTRA的特性方程式與OTA對偶，從這個條件來看，它可能與OTA有對等的優勢。又因為OTRA的輸入端虛接地，因此沒有寄生效應，是唯一可以消除輸入端寄生效應的主動元件，也因為有著這個特別的特性，所以本論文才使用這個元件設計濾波器。本論文使用節點分析設計法，將複雜的電壓式四階橢圓濾波轉移函數，分解成五個簡單的電流方程式，而每一個電流方程式，都是根據OTRA輸入端電流相等的特性完成。在利用正負端電流可以做對調，以及元件放在回授路徑與否，可設計出多種電路結構。多種電路結構經分析後，若所求電壓兩端接到OTRA輸入端，因為OTRA輸入端有虛接地的特性，因此電壓經分壓後為零電壓，所以在從所有的電路中找到五個可運作的電壓式四階橢圓濾波電路，其中元件使用了五個OTRA、四個電容、十二個電阻，實現完成的電路擁有最少電容的優點，並比較五種電路其性能的不同。電路模擬採用H-Spice及Matlab軟體，操作頻率設定在1MHz，從五個電路中選取輸出訊號最好的電路去探討，因為輸出誤差高於3%，因此利用非理想分析找出寄生電容值和寄生電導值，補償過後使輸出訊號接進理論值；最後再利用變動元件百分比進行敏感度分析，並探討元件對電路的影響。

關鍵字

濾波電路；運算轉阻放大器

並列摘要

Many scholars use OTA as active components to design circuits in the past, and OTRA's characteristic equation and OTA on even terms from this condition, it may OTA have equal advantages. And OTRA input virtual ground, so there is no parasitic effect, is the only way to eliminate the parasitic effects of the input active device, as has this special feature, so only use this component in this paper the design filter. Thesis this use node analyze, the complex voltage four-order elliptic filter transfer function will decomposed into five simple current equation, and every one current equation are based on current input OTRA properties equivalent to complete. In the use of positive and negative side current swap can be done, as well as elements in the feedback path or not, you can design a variety of circuit configurations. After analysis a variety of circuit structure, if you are asking the voltage across the input terminals connected OTRA, because there is virtual ground input OTRA characteristics, so this voltage through the partial pressure of zero voltage. The five available voltage-mode fourth-order elliptic low-pass filter circuit, the circuit use five OTRAs, four capacities, twelve resistance, design the circuit finished to the least have advantage of the capacity. Using H-Spice and Matlab software to simulate circuit, the operating frequency set at 1MHz, we select the best output signal of five circuit to explore. Because the output error is greater than 3%, find the parasitic capacitance and parasitic conductance value by non-ideal analysis, then the output signal closed to the theoretical value; Finally, the use of Change the componential percentage to proceed the sensitivity analysis, and to explore the elements affect the circuit.

並列關鍵字

OTRA ； Filter

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] K. C. Smith and A. Sedra, “A second-generation current conveyor and it’s applications”, IEEE Trans., CT-17, pp. 132-134, 1970.

[3] M. Alami and A. Fabre, “Insensitive current-mode bandpass filter implemented from two current conveyors, ” Electronics Letters, vol. 27, no. 11, pp. 897-899, 1991.

[4] A. Fabre, “Third-generation current conveyor：a new helpful active element”, Electron. Lett., vol. 31, no. 5, 1995.

[5] A. Piovaccari, “CMOS integrated third-generation cyrrent conveyor,” Electronics Letters, vol. 31, no. 15, pp. 1228-1229, 1995.

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以運算轉阻放大器為主動元件實現五個電壓式四階橢圓濾波電路之方法與其性能之比較

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