MIXED SIGNAL LETTER

Reply to comment on ‘‘Novel lossless and lossy grounded inductorsimulators consisting of a canonical number of components’’

Erkan Yuce

Received: 1 June 2011 / Revised: 17 May 2012 / Accepted: 24 May 2012 / Published online: 7 June 2012

� Springer Science+Business Media, LLC 2012

This comment reply is related to recently published com-

ment of [1]. It is shown in this comment reply that there are

some misunderstandings in [1] about voltage-mode (VM)

filter example of [2] which operates well and new current

feedback operational amplifier (CFOA) working well in

specific applications.

Electrical symbol of the circuits in [2] is shown in

Fig. 1. Disconnecting VA from ground and applying an

input to VA, a VM low-pass filter can be obtained as shown

in Fig. 2.

From Figs. 1 and 2, corresponding VM filters by using

lossy inductors in [2] are demonstrated in Figs. 3, 4, 5 and

6, respectively.

Transfer function of the filters in Figs. 3, 4, 5 and 6 is

evaluated as follows:

VLP

VA

¼ 1

s2LeqC1 þ sC1Req þ 1ð1Þ

Here, corresponding Leq and Req are given in [2].

‘‘It should be noted that Fig. 2 implies as if, with R2

ungrounded and a voltage VA is applied on the terminal,

the resulting two-port network would represent a floating

series RL impedance between node voltages VLP and VA,

which is obviously not correct. Although the 2-port net-

works derived from the four grounded inductance circuits

of [2], obtained by ungrounding resistor R2 and treating

the terminal thus created as port 2 (with node voltage

VA), do not realize a floating serial RL impedance,

nevertheless, the input current from one side (looking into

the node having voltage VLP) is still inductive (serial RL)

and node equation written on this particular node will,

therefore, still give the correct transfer function of a

second-order low-pass filter even though the current

looking into the node having voltage VA is not exactly

same as the current looking into the node having voltage

VLP. This inequality of currents is true in all the 2-port

networks obtained from the grounded inductor simulators

of [2] derived in the above quoted manner and hence, this

explanation applies to all the four 2-port networks which

are derived from the four grounded inductor circuits of

[2] and are employed in four low-pass filters of Figs. 3, 4,

5 and 6’’. This was commented by an anonymous

reviewer.

In Fig. 7, a well known alternative circuit, current-

mode (CM) low-pass filter, is given in [1]. Also, CM low-

pass filter with an additional CCII for providing high

output impedance current is given in Fig. 8. As depicted

in Fig. 9 of this comment reply, alternative circuits in

Figs. 7 and 8 require extra circuitry for realizing low-pass

current because both of them use floating supply voltages

[1]. Hence, the circuit of Fig. 10 using three CCII?s is

given as an alternative. Fortunately, proposed VM low-

pass filters need an extra one capacitor in addition to a

lossy grounded inductor whereas the well known CM

low-pass filter requires an additional one capacitor and

three CCII?s.

New CFOA of [2] is given in Fig. 11 while alternative

CFOA of [1] is given in Fig. 12. If one replaces new

CFOA of [2] in Fig. 11 instead of grounded inductors in

[2]. It is observed that alternative CFOA in [1] needs no

feedback but proposed CFOA in [2] need a feedback.

Also, all the proposed inductor simulators except the last

one in [2] have a feedback; thus, all of them except the

E. Yuce (&)

Pamukkale University, Denizli, Turkey

e-mail: erkanyuce@yahoo.com

123

Analog Integr Circ Sig Process (2012) 72:505–507

DOI 10.1007/s10470-012-9875-y

last one in [2] can be operated well. In brief, the CFOA in

Fig. 12 is true in general while one in Fig. 11 is true in

specific applications.

Fig. 6 VM low-pass filter obtained from the lossy inductor in [2]

Fig. 7 Alternative circuit of [1]

Fig. 8 Alternative circuit of [1] for realizing high output impedance

current

Fig. 3 VM low-pass filter obtained from the lossy inductor in [2]

Fig. 4 VM low-pass filter obtained from the lossy inductor in [2]

Fig. 2 VM low-pass filter example

Fig. 1 Electrical symbol of the circuits in [2]

Fig. 5 VM low-pass filter obtained from the lossy inductor in [2]

506 Analog Integr Circ Sig Process (2012) 72:505–507

123

Acknowledgments I would like to thank the anonymous reviewers

and associate editor for their invaluable comments for improving the

paper.

References

1. Abuelma’atti, M. T. (2011). Comment on ‘‘Novel lossless and

lossy grounded inductor simulators consisting of a canonical

number of components’’. Analog Integrated Circuits and SignalProcessing. doi:10.1007/s10470-011-9634-5.

2. Yuce, E. (2009). Novel lossless and lossy grounded inductor

simulators consisting of a canonical number of components.

Analog Integrated Circuits and Signal Processing, 59, 77–82.

Erkan Yuce was born in 1969

in Nigde, Turkey. He received

the B.Sc. degree from Middle

East Technical University, the

M.Sc. degree from Pamukkale

University and the PhD. degree

from Bogazici University all in

Electrical and Electronics Engi-

neering in 1994, 1998 and 2006,

respectively. He is currently an

Associative Professor at the

Electrical and Electronics Engi-

neering Department of Pam-

ukkale University. His current

research interests include analog

circuits, active filters, synthetic inductors and CMOS based circuits.

He is the author or co-author of about 90 papers published in scientific

journals or conference proceedings.

Fig. 9 Complete circuit of the inductor in [1]

Fig. 10 CM low-pass filter in which a capacitor is not shown

Fig. 11 New CFOA in [2]

Fig. 12 Alternative CFOA in [1]

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