1. The document describes a simulation of floating resistors of different values that are used as feedback in an OTA band pass filter structure. 2. The simulated floating resistances show good agreement between theoretical and simulated circuit values. 3. A band pass response is observed in the tunable frequency range from the bias current, with a designed quality factor.

1. http://www.iaeme.com/IJECET/index.asp 28 editor@iaeme.com
International Journal of Electronics and Communication Engineering & Technology
(IJECET)
Volume 6, Issue 8, Aug 2015, pp. 28-34, Article ID: IJECET_06_08_005
Available online at
http://www.iaeme.com/IJECETissues.asp?JTypeIJECET&VType=6&IType=8
ISSN Print: 0976-6464 and ISSN Online: 0976-6472
© IAEME Publication
BAND PASS DESIGN WITH FLOATING
RESISTOR SIMULATION APPLICATION AS
FEEDBACK USING OPERATIONAL
TRANSCONDUCTANCE AMPLIFIER
Manjula V. Katageri
Government First Grade College, BAGALKOT, India
M. M. Mutsaddi
Basaveshwar Science College, BAGALKOT, India
Rajeshwari S. Mathad
Basaveshwar Science College, BAGALKOT, India
ABSTRACT
The simulation of resistance using OTA has shown stable results of
resistance which have close agreement in theoretical and in practical values
using simulation circuits. A simulation of floating resistor of different values
has been used as feedback in OTA band pass structure. A close observation of
the structure in band pass range has good agreement in theoretical values and
practical values of the circuit. A band pass is observed in tunable range of
frequency from the bias current with a designed quality factor. The designed
filter has applications in instrumentation using transducers.
Key words: Resistance simulation, OTA-Operational Transconductance
Amplifier, Band pass filter
Cite this Article: Manjula V. Katageri, M. M. Mutsaddi and Rajeshwari S.
Mathad. Band Pass Design with Floating Resistor Simulation Application as
Feedback Using Operational Transconductance Amplifier. International
Journal of Electronics and Communication Engineering & Technology, 6(8),
2015, pp. 28-34.
http://www.iaeme.com/IJECET/issues.asp?JTypeIJECET&VType=6&IType=8
1. INTRODUCTION
Electronically tunable resistors have significant role in the analog circuit design. They
are useful in variety of applications in analog circuit in voltage controlled amplifiers,
automatic gain controlled circuits, automatic tuned filters and oscillators. The
Operational Transconductance Amplifier is one device, in which the transconductance

2. Band Pass Design with Floating Resistor Simulation Application as Feedback Using
Operational Transconductance Amplifier
http://www.iaeme.com/IJECET/index.asp 29 editor@iaeme.com
property helps to simulate grounded and floating resistors with respect to bias current.
The simulated resistances from ohms to hundreds of K ohms are obtained with respect
to single parameter of variation of biasing current of OTA. Using the floating
simulated resistor the band pass filter with minimum number of OTA is designed.
The Operational Transconductance Amplifier is a device in which the input
voltage controls the output current. It contains the feature of linear controlled
transconductance with tunable property of bias current. The magnitude of resistance
can be electronically varied by changing the external bias current of OTA.
LM13600/LM13700 consists of two current controlled transconductance amplifiers
with different inputs and push pull outputs. The ideal OTA has Zin=∞, Zout=∞,
Inverting input current is equal to non inverting input current. The Fig.1 shows circuit
symbol of OTA. The voltage controlled current source is mathematically expressed
as,
Iout= gm (VA - VB), Where gm = (Ibias/2VT), VT is thermal Voltage = T/11600
=26mV at 280
C of room temperature.
Fig.1 Circuit symbol of OTA
2. CIRCUIT DESCRIPTION
The simulation of the grounded resistor by taking feedback path of OTA on either of
the input terminal for positive and negative resistor respectively as shown in Fig (2).
The resistance values are varied with respect to biasing current is given by the Eqn.
(1)
R = = (1)
Figure 2 Simulated grounded Resistor
The floating resistor can be simulated with two OTAs as shown in Fig.3. By
analysis of the circuit, it gives an admittance matrix as
Y = where R = 1/gm (2)
Thus realizes the ideal floating resistor.

3. Manjula V. Katageri, M. M. Mutsaddi and Rajeshwari S. Mathad
http://www.iaeme.com/IJECET/index.asp 30 editor@iaeme.com
Figure 3 Simulated floating resistor
The simulated floating resistance is verified through band pass structure using one
OTA with feedback floating resistor, which is shown in Fig. 4. The resistance is
replaced with the simulated floating resistor of two OTA circuit as shown in Fig. 5.
Figure 4 Band pass filter with feedback resistor
Figure 5 Bandpass filter with simulated feedback resistor

4. Band Pass Design with Floating Resistor Simulation Application as Feedback Using
Operational Transconductance Amplifier
http://www.iaeme.com/IJECET/index.asp 31 editor@iaeme.com
By analyzing the circuit the transfer function of Band pass filter at gm1=gm2=gm is
obtained as
The centre frequency is and quality factor is This
is verified experimentally through Proteus Professional Software.
3. EXPERIMENTAL RESULTS
The simulated grounded and floating resistor values are experimentally verified with
LM13600 of OTA [3-6]. The bias current of OTA is varied from 0.1uA to 1mA at
room temperature, which gives theoretical values of resistances in the range 520KΩ
to 0.052KΩ respectively. These are verified using Proteus Professional Software
which produces good results in filter designs. In the laboratory, the simulated values
are in well agreement with theoretical values for biasing current in between 10uA to
500uA. Beyond this range there is variation in simulation of resistance, because the
input offset voltage varies as biasing current near 1uA and 1000uA of LM13600N
OTA. The variation of bias current with log R is shown in “Fig.6” [1-6].
Figure 6 Variation of biasing current with Log R
The same simulated resistances are used in the design of band pass filter, shown in
“Fig. 7”. For unity quality factor IB1=IB2=IB3=IB, & C1=C2=C. At Ibias = 100µA & C =
10nF, the centre frequency fo = = 30.5KHz theoretically, where as experimental
observation gives well structure of band pass filter of fo = 30.9 KHz with -3.0db gain
and bandwidth of 57.2KHz with roll off rate -40db per decade is shown in “Fig.8”.
0.01
0.1
1
10
100
1000
10000
0 1 2 3 4 5 6 7
BiasingCurrentinμA
Log R
Variation of biasing current Vs. Log R
R(Th)
R(Pr)

5. Manjula V. Katageri, M. M. Mutsaddi and Rajeshwari S. Mathad
http://www.iaeme.com/IJECET/index.asp 32 editor@iaeme.com
Figure 7 Experimental simulated Band pass filter
This simulated resistance is verified in band pass for biasing currents from 1µA to
1000µA, which gives a very good agreement with theory. At IB1=IB2=IBias = 100µA
for simulated resistance of 520Ω, C1 = 10nF and C2 = 10pF, for IB3= 1uA gives a wide
band pass filter with -20dB per decade roll off. The -3dB frequencies are ranging
from. 204 Hz to 9.75 MHz & its band width is 9.749MHz, which is shown in “Fig. 9”.
The flatness of band pass filter depends on the difference between values of
capacitors. Greater the difference greater will be the flatness and the positive gain
changes with respect to the capacitor C2 and the bandwidth depends on biasing
currents. This is advantageous parameter which helps to select the bandwidth with
positive gain. [7-10]
Figure 8 Frequency Response at Q=1
3
4
5
116
1
2
7
8
U1:A
LM13600
C1
10nf
C2
10pf
U1:A(AMPBIAS)
input Vin
Vout
14
13
12
116
16
15
10
9
U1:B
LM13600
3
4
5
116
1
2
7
8
U2:A
LM13600
U2:A(V-)
U1:B(V+)
U1:B(AMPBIAS)

6. Band Pass Design with Floating Resistor Simulation Application as Feedback Using
Operational Transconductance Amplifier
http://www.iaeme.com/IJECET/index.asp 33 editor@iaeme.com
Figure 9 Frequency Response for wide band structure
4. CONCLUSION
The simulation of grounded and floating resistance using Operational
Transconductance Amplifier gives a well agreement with theoretical values. The
application of simulated floating resistance in feedback of OTA band pass filter shows
good results in respect of the selectivity. For unity quality factor the biasing currents
and capacitors of desired equal value gives narrow band pass filter, whose centre
frequency can be selected with reduced bandwidth [3-10]. A basing current of 1μA
with floating resistor of 520Ω gives wideband pass structure with C1 greater than C2
gives bandwidth 9.7MHz. This bandwidth with positive gain is dependent on the
difference between C1 and C2. Greater the difference greater will be the flatness is
observed. For selected values of C1 and C2 with C1 greater than C2 the bandwidth is
more selective to the biasing currents of IB3 with respect to simulate floating
resistance. The floating resistor simulation is one advantageous for selecting the
bandwidth, centre frequency and quality factor with respect to biasing current of
Operational Transconductance Amplifier. The designed filter has applications in
instrumentation using transducers.
REFERENCES
[1] Randll L. Geiger and Edgar Sanchez- Sinencio Active Filter Design Using
Operational Transconductance Amplifiers: A Tutorial, IEEE Circuits and devices
Magazine, 1, March 1985, pp 20-32
[2] I.A. Khan, M. T. Ahmed. Realisation Of Tunable Floating Resistors, Electronics
22(5), Letters 17th
july 1986
[3] Khanittaha Kaewdang, kiattisak Kumwachara and wanlop Surakampontorn,
Electronicallytunable Floating Cmos Resistor Using Ota, IEEE, Proceedings of
ISCIT 2005
[4] R.G.Carvajal, J Galan, A, Torralba and et. Al. A Very Linear Ota With V-I
Conversion Based On Quasi-Floating MOS Resistor, IEEE, 1-1244-0921-7/07 ,
2007

7. Manjula V. Katageri, M. M. Mutsaddi and Rajeshwari S. Mathad
http://www.iaeme.com/IJECET/index.asp 34 editor@iaeme.com
[5] Bhaba priyo Das, Neville Watson and yonghe Liu, Simulation of Voltage
Controlld Tunable All Pass Filter Using 1700 Ota, International Journal of
Electrical and Computer Engineering 5-6-2010
[6] Montree Kumngern. New Electronically Tunable Voltage Mode Low Pass,High
Pass, Bandpass Filter Using Simple Ota’s, International Journal And Electrical
Engineering, 3(5), 2011, pp-649-53
[7] Dattaguru V. Kamath. Novel of OTA-C current mode third order band pass
filters, International journal of innovative research in electronics,
instrumentation and control engineering,2(8), August 2014
[8] Rajeswari S. Mathad and et. al, Studies on active filters using OTAC and oyher
current conveyors, International Journal of advanced Computer and
mathematical Sciences, 2(3), 2011, pp 155-159
[9] Montree Kumngern. New electronically tunable voltage mode low pass ,high
pass, band pass filter using simple OTA’s, International Journal of Computer
and Electrical engineering, 3(5),Oct-2011
[10] Jagadeep Kaur sahani, et.al, Design of second order low pass and high pass filter
using double gate Mosfet based OTA, Innovative systems design and engineering
5(4),2014
[11] Roma Rani, Pankaj Rai and Jyoti Athiya. Design and Analysis of Second
Generation Current Conveyor Based Low Power Operational Transconductance
Amplifier. International Journal of Electrical Engineering & Technology, 6(4),
2015, pp. 9 - 15.
[12] Mohammed Arifuddin Sohel, Dr. K. Chennakeshava Reddy and Dr. Syed Abdul
Sattar. Linearity Enhancement of Operational Transconductance Amplifier Using
Source Degeneration. International Journal of Advance in Research Engineering
& Technology, 4(2), 2015, pp. 257-263.