Journal of Phsical Sciences, Vol. 11, 2007, 124132 Current Conveor Simulation Circuits Using Operational Amplifiers S. ana* and K. Pal** *D.A.V. Centenar Public School, Hardwar, Uttranchal, India. Email : seema.rana@gmail.com. ** Department of Earthquake Engineering, IIT oorkee, oorkee, India. Email : kiratfeq@iitr.ernet.in. eceived April 3, 2007 ; accepted August 10, 2007 1. Introduction ABSTACT In this paper one circuit simulating a second generation current conveor (CCII) is reported. The circuit uses four operational amplifier and gives low tracking error. This circuit realises both positive and negative polarit second generation current conveor. Based on this circuit a simulation circuit for dual output current conveor (DOCCII) is also described. Finall a generalied CCII circuit is proposed which b control of logic 0 or 1 at a control terminal of analog multipleer gives CCII+ or CCII simulation. These simulations are used in verifing the CCII and DOCCII based circuits eperimentall, and are economical. The second generation current conveor CCII introduced b Sedra and Smith [1] is widel used in realisation of filters and oscillators [27]. It is available with both polarit as CCII+ and CCII. B connecting CCII+ and CCII together a dual output CCII (DOCCII) is formed which has got its importance in current mode filter realisations [8 9]. To eperimentall test the circuit based on these elements several discrete or spice models are available in literature [1016]. In this work two circuits of simulating CCII and DOCCII are given which purel uses IC741 operational amplifier, available at ver low cost. These simulations are most attractive in research laborator to practicall test the performance of CCII and DOCCII based realiations. 2. Circuit Description The first proposed circuit is shown in fig.1. This circuit has been obtained b modifing the circuit of Huertas [10] shown in fig.2 124
Current Conveor Simulation Circuits Using Operational Amplifiers 125 V i V 1 A V 2 B Fig.1 A modified configuration of second generation current conveor [CCII] V i V 1 A V 3 V B V 4 V 5 I I V 2 Fig. 2.Circuit reported b Huertas [10]
126 S. ana and K. Pal The characteristics of second generation current conveor (CCII) for which this circuit is proposed is as follows: CCII (+): i = 0, v = v, i = i CCII (): i = 0, v = v, i = i smbolic representations of CCII (+) and CCII () are given in fig. 3. CCII(+) (a) CCII() (b) Fig.3 : Smbolic representations of CCII (+) and CCII ()[ a & b ] For a non ideal CCII: i = 0, v = v (1+ε 1 ), i = i (1+ε 2 ) where ε 1 and ε 2 are non idealities 2.1 Analsis In this circuit terminal is the non inverting terminal of operational amplifier ( 1), which has high input impedance, thus i = 0,
Current Conveor Simulation Circuits Using Operational Amplifiers 127 Also in an operational amplifier inverting terminal follows the non inverting terminal, therefore v = v. To prove third condition i = i for CCII (+) connect V 1 to A and V 2 to B. Assume I current flows through terminal towards ground. V1 V2 i = (1) V Now 1 V3 V3 V5 i1 = = (2) 1 1 which gives V 5 = 2V 3 V 1 (3) Similarl V = 2V 4 V 2 (4) as inverting terminal voltage of an operational amplifier is equal to non inverting terminal voltage V 4 = V 3 and eqn. (3) and (4) gives V 5 V = V 1 V 2 V V V or 5 V 1 2 = or i = i Hence this circuit simulates a CCII (). Since no current is drawn b non inverting terminals of operational amplifiers in unit gain,i and i flows through respective resistance onl, thus tracking error is practicall ero. In case of circuit of Huertas [10] it is not ero. Also the circuit of Huertas uses high valued resistances for, the present circuit can use low value and it can be equal to also. Thus all si resistances of equal values makes circuit realisation simple. B connecting V 1 to B and V 2 to A, a CCII () is realised. The another active element dual output current conveor (DOCCII) is also used in the realisation of filters etc. Based on the circuit of fig.1 one can easil realise a circuit simulating DOCCII as shown in fig.5. It uses si operational amplifiers and has the following terminal properties i = 0, v = v, i = i i = This circuit also offers low tracking error. DOCCII Fig.4 : Smbolic representations of DOCCII
128 S. ana and K. Pal Fig.5 : A practical DOCCII implementation circuit. Finall a generalised current conveor simulation (GCCII) as shown in fig.6 is proposed. The circuit uses a analog multipleer IC4502 which through logic 0 or 1 at control terminal C gives CCII+ or CCII respectivel.
Current Conveor Simulation Circuits Using Operational Amplifiers 129 o o + O.A. + O.A. V 1 A V 2 B O.A. + + O.A. o o C +V cc V o E 9 10 16 1 4 5 0 12 3 5 14 6 2 13 7 8 Fig.6 : A GCCII Circuit.
130 S. ana and K. Pal 3. Eperimental esults All these circuits were tested for a.c. input at 1KH as an amplifier configuration V0 shown in fig.7. The voltage gain is given as V i V0 2 = ± Vi 1 where + sign stand for CCII (+) and sign stand for CC (). Choosing = 10KΩ and 2 = 10KΩ, 20KΩ, 30KΩ, 100KΩ, The circuit were tested for different gain and eperimental results were found in good agreement with the theor. In another eperiment the circuit of DOCCII was tested as amplifier configuration with resistance 10KΩ at w.r.t. ground and resistances of 20KΩ at and 10KΩ at terminal w.r.t. ground. The waveforms for an input of 100mv at 1KH and output for a gain of 2.0 and 1.0 are shown in fig.8. The voltage waveform at terminal has a gain of 2.0 and is in phase with voltage at, while same at is out of phase and has unit gain as designed. In the realisation of CCII+ and DOCCII the IC741 were used and value of resistances = 1.0KΩ and =10KΩ. V i CCII(+) V 0 2 Fig.7. An amplifier circuit using CCII
Current Conveor Simulation Circuits Using Operational Amplifiers 131 Fig. 8. Input and output waveforms of DOCCII. Using CCII simulated circuit of fig.1 the all pass filter circuits of Khan & Maheshwari [17] and Pal [18] were tested and result were found ver satisfactor. 4. Conclusions A circuit simulating a second generation current conveor (CCII) is reported. The circuit uses four operational amplifier and gives low tracking error. This circuit realises both positive and negative polarit second generation current conveor. Based on this circuit a simulation circuit for dual output current conveor (DOCCII) is also described. Finall a generalied CCII circuit is proposed which b control of logic 0 or 1 at a control terminal of analog multipleer gives CCII+ or CCII simulation These simulations are used in verifing the CCII and DOCCII based circuits eperimentall, and are economical.
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