Schmitt Trigger with Controllable Hysteresis Using Current Conveyors

Jiri Misurec, Jaroslav Koton


Active elements working in the current or mixed mode are still attractive for the design of analog functional blocks. The current conveyor (CC) was defined already in 1968. This paper deals with hysteresis comparators using second generation current conveyor. The comparator is basically a pulse circuit. In these circuits, the maximum rate of change in the output voltage is required during switching from one state to another. In comparators with operational amplifiers the switching time is given by the slew rate of the operational amplifier used, which is not too high. If a current conveyor is used, the time of switching the comparator gets shorter. The comparator is capable to operate at a higher frequency bands and if it is used, for example, in converters, a higher operating frequency can be reached. The connection of an inverting and a non-inverting comparator with adjustable hysteresis is shown as a practical implementation. Using the AD844, results of experimental measurements are presented that confirm the theoretical  assumptions and the results of computer simulation.

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K. C. Smith and A. Smith, “The Current Conveyor: a New Circuit Building Block,”IEEE Proc., Vol. 56, pp. 1368-1369, 1968.

A. Sedra and K. C. Smith, “A second-generation current conveyor and its application,”IEEE Trans. Circuit Theory, Vol. 17, pp. 132-134, 1970.

A. Fabre, “Third-generation current conveyor: a new helpful active element,”Electronics Letters, Vol. 31, No. 5, pp. 338-339, 1995.

M. Sagbas, K. Fidanboylu, and M. C. Bayram, “Triple-input Single-output Voltage-mode Multifunction Filter Using Only Two Current Conveyors”, Trans. Engineering, Computing and Technology, Vol. 4, pp. 105-108, 2005.

S. Minaei, O. K. Sayin, and H. Kuntman, “A new CMOS electronically tunable current conveyor and its application to current-mode filters”, Tran. Circuits and Systems I, Vol. 53, pp. 1448-1457, 2006.

S. A. Mahmoud, M. A. Hashiesh, and A. M. Soliman, “Digitally controlled fully differential current conveyor: CMOS realization and applications”, in Proc. IEEE Int. Symp. Circuits and Systems - ISCAS, Vol. 2, pp. 1622-1625, 2005.

P. Prommee, M. Somdunyakanok, and S. Toomsawasdi, “CMOS-based current-controlled DDCC and its applications”, in Proc. IEEE Int. Symp. Circuits and Systems - ISCAS, pp. 1045-1048, 2010.

S. Ozoguz and A. Acar, “On the realization of floating immittance function simulators using current conveyors”, Int. J. Electronics, Vol. 85, No. 4, pp. 463-475, 1998.

U. Cam, O. Cicekoglu, and H. Kuntman, “Universal series and parallel immittance simulators using four terminals floating nullors,”Analog Integrated Circuit and Signal Processing, Vol. 25, No. 1, pp. 5966, 2000.

E. Arslan, B. Metin, C. Cakir, O. Cicekoglu, “A novel grounded lossless inductance simulator with CCI”, in Proc. Int. XII. Turkish Symposium on Artificial Inteligence and Neural Networks, 2003.

E. Yuce, S. Minaei, and O. Cicekoglu, “A novel grounded inductor realization using a minimum number of active and passive components”, ETRI Journal, Vol. 27, pp. 427 - 432, 2005.

S. Bima, A. Khan, S. Roy, and K. Dey, “Programmable Hysteresis Comparator Circuits using Current Conveyor,”J. Instrum. Soc. India, No. 32, pp.85-93, 1997.

S. Del Re, A. De Marcellis, G. Ferri, and V. Stornelli, “Low voltage integrated astable multivibrator based on a single CCII”, in Proc. Research in Mincroelectronics and Electronics Conference, pp. 177-180, 2007.

P. Silapan and M. Siripruchyanun, “A Simple Current-mode Schmitt Trigger Employing Only Single MO-CTTA”, in Proc. 6th Int. Conf. Electrical Engineering/Electronics, Computer, Telecommunications and

Information Technology - ECTI-CON, Vol. 01, pp. 556-559, 2009.

P. Silapan and M. Siripruchyanun, “Fully and electronically controllable current-mode Schmitt triggers employing only single MO-CCCDTA and their applications ”, Analog Integr Circ Sig Process, doi:10.1007/s10470-010-9593-2, Vol. 68, pp. 111-128, 2011.

Datasheet AD844: 60 MHz 2000V/µs Monolithic Op Amp, Analog Devices, Rev. F. 2009.

A. Fabre, O. Saaid, F. Wiest, and C. Baucheron, High frequency applications based on a new current controlled conveyor, IEEE Trans. Circuits Syst.-I, Vol. 43, No. 2, pp. 82-90, 1996.

H.O. Elwan and A.M. Soliman, Novel CMOS differential voltage current conveyor and its applications, IEE Proc. Circuits, Devices, Systems, Vol. 144, No. 3, pp. 195-200, 1997.

S. Minaei, O.K. Sayin, and H. Kuntman, A new CMOS electronically tunable current conveyor and its application to current-mode filters, IEEE Trans. Circuits Systems I, Vol. 53, No. 7, p. 1448-1457, 2006.

W. Surakampontorn and K. Kumwachara, CMOS-based electronically tunable current conveyor, Electronics Letters, Vol. 28, No. 14, pp. 1316-1317, 1992.

Datasheet AD7533: CMOS low cost 10-bit multiplying DAC, Analog Devices, Rec. C, 2007.



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