CS  Vol.2 No.1 , January 2011
A Novel Multifunction CFOA-Based Inverse Filter
Abstract: We present a novel multifunction inverse biquad configuration based on current feedback operational amplifiers (CFOAs) and grounded passive elements. The proposed scheme can be used to realize inverse lowpass, inverse bandpass and inverse highpass filter functions. The relevant coefficients of the inverse filters are orthogonal adjustable by independent passive elements. All the passive elements in the proposed scheme are grounded to benefit easier electronic tunability. With the high input impedance and low output impedance properties, the scheme is input and output cascadable for voltage operation. The feasibility of the proposed scheme is demonstrated by HSPICE simulations.
Cite this paper: nullH. Wang, S. Chang, T. Yang and P. Tsai, "A Novel Multifunction CFOA-Based Inverse Filter," Circuits and Systems, Vol. 2 No. 1, 2011, pp. 14-17. doi: 10.4236/cs.2011.21003.

[1]   A. Leuciuc, “Using Nullors for Realisation of Inverse Transfer Functions and Characteristics,” Electronics Letters, Vol. 33, No. 11, 1997, pp. 949-951. doi:10.1049 /el:19970637

[2]   R. Kuc, “Introduction to Digital Sig-nal Processing,” McGraw-Hill, New York, 1988.

[3]   B. Chipipop and W. Surakampontorn, “Realisation of Current-Mode FTFN-Based Inverse Filter,” Electronics Letters, Vol. 35, No. 9, 1999, pp. 690-692. doi:10.10 49/el:19990495

[4]   H. Y. Wang and C. T. Lee, “Using Nullors for Realisation of Current-Mode FTFN-Based Inverse Filters,” Electronics Letters, Vol. 35, No. 22, 1999, pp. 1889-1890. doi:10.1049/el:19991336

[5]   M. T. Abuelma’atti, “Identification of Cascadable Cur-rent-Mode Filters and Inverse-Filters Using Single FTFN,” Frequenz, Vol. 54, No. 11, 2000, pp. 284-289.

[6]   S. S. Gupta, D. R. Bhaskar, R. Senani and A. K. Singh, “Inverse Active Filters Employing CFOAs,” Electrical Engineering, Vol. 91, No. 1, 2009, pp. 23-26. doi:10.10 07/s00202-009-0112-3

[7]   G. H. Wang, Y. Fukui, K. Kubota and K. Watanabe, “Voltage-Mode to Current-Mode Conversion by an Extended Dual Transformation,” IEEE Proceedings International Symposium on Circuits and Systems, Singapore, 11-14 June 1991, pp. 1833-1836.

[8]   Analog Devices, 60 MHz 2000 V/μs Monolithic Op Amp AD844 Data sheet, Revision E, 2003. http://www.

[9]   A. Fabre, “Insensitive Voltage-Mode and Cur-rent-Mode Filters from Commercially Available Tran-simpedance Opamps,” Circuits, Devices and Systems, IEE Proceedings G, Vol. 140, No. 5, 1993, pp. 319-321. doi:10.10 49/ip-g-2.1993.0053

[10]   B. Nauta, “Analog CMOS Filters for Very High Frequencies,” Kluwer Academic Publishers, Norwell, 1993.

[11]   I. A. Khan and M. T. Ahmed, “OTA-Based Integrable Vol-tage/Current-Controlled Ideal C-Multiplier,” Electronics Letters, Vol. 22, No. 7, 1986, pp. 365-366. doi:10. 1049/el:19860248

[12]   K. Vavelidis and Y. Tsividis, “Design Considerations for a Highly Linear Electronically Tunable Resistor,” ISCA ’93, 1993 IEEE International Symposium on Circuits and Systems, Vol. 2, Chicago, 3-6 May 1993, pp. 1180-1183.

[13]   A. Worapishet and P. Khumsat, “Sub-Threshold R- MOSFET Tunable Resistor Technique,” Electronics Let-ters, Vol. 43, No. 7, 2007, pp. 390-392. doi:10.1049/el: 20070175

[14]   J. A. Svoboda, L. McGory and S. Webb, “Applications of a Commercially Available Current Conveyor,” International Journal of Electronics, Vol. 70, No. 1, 1991, pp. 159-164. doi:10.1080/00207219108921266