ELEKTRONIKA IR ELEKTROTECHNIKA,ISSN 1392-1215,VOL.23,NO.2,2017
1Abs ac —This pape p esen s new loa ing induc ance
simula o based on h ee elec onically con ollable cu en
con eyo s (ECCIIs) and di e en ial ol age bu e (DVB). The
induc ance simula o o e s simple elec onic con ol o
induc ance alue as well as simple con ol o losses by change o
pa ame e s o ac i e elemen s. Based on his loa ing induc ance
simula o , example o econnec ion-less econ igu able pseudo-
di e en ial i s -o de il e , allowing change o ans e
unc ion be ween high-pass and in e ing all-pass esponse, is
discussed and s udied. Mo eo e , he p oposed s uc u e can be
easily ex ended o a pseudo-di e en ial second-o de band-bass
il e . Beha iou o p esen ed solu ions is e i ied by PSpice
simula ions and also expe imen ally in equency band up o
10 MHz. Ob ained esul s con i med expec ed ea u es.
Index Te ms—Di e en ial ac i e il e ; di e en ial mode;
pseudo-di e en ial-mode; elec onic con ol; induc ance
simula o ; econ igu abili y.
I. INTRODUCTION
In gene al, ully-di e en ial (symme ical) ci cui s ha e
many applica ions due o speci ic ea u es hey o e , i.e.
a enua ion o common-mode noise as well as be e
ejec ion o signals incoming om powe supply sou ces and
possibly also be e dynamics in compa ison o single-ended
ci cui ies [1]–[4]. Howe e , inc eased complexi y o
ci cui y is cos o hese bene i s. Elec onic con ollabili y
o pa ame e s o analogue and mixed-mode ci cui s is use ul
in single-ended as well as in case o di e en ial-mode
ope a ion. The e o e, ci cui solu ions allowing hese
ea u es a e subjec s o in e es o many esea che s [4].
Digi al con ol o impo an pa ame e s o he di e en ial-
Manusc ip ecei ed 23 Decembe , 2016; accep ed 18 Ma ch, 2017.
Resea ch desc ibed in his pape was inanced by Czech Minis y o
Educa ion in ame o Na ional Sus ainabili y P og am unde g an
LO1401. Fo esea ch, in as uc u e o he SIX Cen e was used. Resea ch
desc ibed in he pape was suppo ed by Czech Science Founda ion
p ojec s unde No. 16-11460Y.
il e was also in es iga ed in he pas [5].
Di ision o di e en ial sys ems ( o example see [1]–[8])
o uly-di e en ial and so-called pseudo-di e en ial-mode
o ope a ion, is pe ec ly explained in [8] which b ings new
insigh in o his esea ch opic. No e ha complexi y o
pseudo-di e en ial-mode ci cui s is signi ican ly educed in
compa ison o ully-di e en ial-mode solu ions due o
pa ially g ounded subpa s o di e en ial sys ems, i.e. inpu
and ou pu po s a e di e en ial whe eas hei inne ci cui y
consis s o g ounded (analog g ound) passi e componen s
and e minals. Many om p e iously epo ed pseudo-
di e en ial ci cui solu ions we e ocused on biquad a ic
(second-o de ) ac i e il e s, [6]–[9] o ins ance. Elec onic
con ollabili y [6] as well as mul i- unc ionali y (p o iding
se e al ans e esponses) [7] we e also s udied in he pas .
In his pape we a e in oducing a no el solu ion o
loa ing induc ance simula o allowing ea u es no epo ed
in p e ious wo ks. These ea u es a e bene icial especially in
elec onic econ igu a ion o ans e unc ion and elec onic
con ol o pseudo-di e en ial-mode il e pa ame e s. He e
p oposed il e ing applica ions can be di ided o wo g oups:
(i) i s -o de econ igu able il e , (ii) second-o de band-
pass il e . Compa ison o selec ed solu ions o i s -o de
ac i e il e s in single-ended, ully-di e en ial, o pseudo-
di e en ial o m [10]–[14] is a ailable in Table I. In
gene al, many o hese ha e mul i unc ional ea u es,
howe e , ea u es such as econnec ion-less econ igu abili y
(possible o ob ain a ious ans e esponses wi hou change
o inpu /ou pu e minal) we e s udied only in single-ended
il e ing solu ions (see o example [15]). To he bes o
au ho s’ knowledge, ci cui s allowing econ igu a ion o
ans e esponses, i.e. ce ain mul i- unc ionali y o he il e
be ween a leas wo di e en ypes o ully-di e en ial o
pseudo-di e en ial il e s we e no epo ed in he open
li e a u e ye . He e p esen ed s uc u e o loa ing induc ance
simula o allows such elec onic econ igu a ion, i i s
Pseudo-Di e en ial Fil e Design Using No el
Adjus able Floa ing Induc ance Simula o wi h
Elec onically Con ollable Cu en Con eyo s
Roman So ne 1,2, No be He encsa 2, Jan Je abek2, Aslihan Ka ci1,2, Ja osla Ko on2, Tomas Dos al3
1Depa men o Radio Elec onics, Facul y o Elec ical Enginee ing and Communica ion,
B no Uni e si y o Technology,
Technicka 12, B no, 616 00, Czech Republic
2Depa men o Telecommunica ions, Facul y o Elec ical Enginee ing and Communica ion,
B no Uni e si y o Technology,
Technicka 12, B no, 616 00, Czech Republic
3Depa men o Technical S udies, College o Poly echnics Jihla a,
Tols eho 16, Jihla a 586 01, Czech Republic
[email p o ec ed].cz
h p://dx.doi.o g/10.5755/j01.eie.23.2.17996
31
ELEKTRONIKA IR ELEKTROTECHNIKA,ISSN 1392-1215,VOL.23,NO.2,2017
implemen a ion is app op ia e, as i is shown in his pape .
TABLE I. COMPARISON OF REPORTED PSEUDO/FULLY-
DIFFERENTIAL FIRST-ORDER MULTIFUNCTIONAL FILTERS.
Wo k
No. o pas./ac .
elemen s
A ailable
unc ions
T ans e esponse
con igu abili y
[10]
4-6/1
AP, BR
No
[11]
2-6/1-2
LP, HP, AP
No
[12]
4/1
AP
No
[13]
4/2
AP, LP
No
[14]
1/3
AP
No
Fig. 3
2(6)/1(4)
HP, iAP
Yes
No e: (i) DT – (in e ing) di ec ans e ; (i) AP – (in e ing) all-pass; LP
– low-pass; (i) HP – (in e ing) high-pass; BR – band ejec .
II. DESCRIPTION OF FLOATING INDUCTANCE SIMULATOR
P oposed loa ing induc ance simula o shown in Fig. 1
employs h ee elec onically adjus able cu en con eyo s o
second gene a ion (ECCIIs) [16] desc ibed by he ollowing
in e - e minal ans e s: IZ=B.IX,VX=VY,IY= 0 and one
di e en ial ol age bu e (DVB) [16] p o iding he
ollowing ope a ion: V+V=Vou . No e ha he cu en
gain Bo each ECCII is con ollable linea ly by DC ol age
(BVSET_B). Comme cially a ailable de ices EL2082 and
AD830 a e examples o p e iously discussed elemen s
(ECCII, DVB) wi h well- i ing beha iou up o se e al ens
o MHz. Assuming Rx1 =Rx2 =R3a e equal and designa ed
as RL_in , he admi ance desc ip ion (based on me hod o
unknown nodal ol ages: I=Y×V) o he ci cui in
Fig. 1 p esen s se o equa ions:
1 1
1 1
1 1
1 1
2 2
2 2
,
inp inp
Inp inp
I V
a B a B
I V
a B a B
 
 
 
   

 

   
 
   

   
 
(1)
whe e
 
2
_ in _ in 3 _ in
2
L L L
a sC R B R  
.
Then, assuming B1=B2=B1,2, impedance o equi alen
induc ance emula o has he ollowing heo e ical o m
 
_ in _ in
2
_ in _ in 3 _ in
1,2 1,2
( )
2,
eq eq s
L L L
L s sL R
sC R B R
B B
  

 
(2)
whe e CL_in and RL_in a e passi e elemen s o he induc ance
simula o and i is clea ha he p oposed ci cui beha es as
lossy induc ance. Howe e , he lossy pa Rs_in in (1) can be
easily elimina ed by selec ing cu en gain B3(ECCII3) equal
o 2, losses a e nega i e o B3> 2. Ne e heless, lossy pa
o he p oposed induc ance simula o can be also bene icial
o applica ion as in oduced la e . Mo eo e , i is ob ious
ha alue o Leq_in can be con olled elec onically by B1and
B2.
P oposed induc ance simula o in Fig. 1 was designed o
u he implemen a ions wi h he ollowing alues o in e nal
elemen s: RL_in = 560 ,CL_in = 470 pF as a pa icula
example. The PSpice simula ion esul s o he induc ance
simula o in g ounded o m a e shown in Fig. 2. Induc ance
alue Leq was changed om 2.63 H o 0.13 H by VSET_B1,2
be ween 0.1 and 2 V, i.e. gains B1and B2a e be ween 0.1
and 2.
III. INDUCTANCE SIMULATOR IMPLEMENTATION IN PSEUDO-
DIFFERENTIAL FILTERING APPLICATIONS
Bene i s o he p oposed solu ion we e e i ied in se e al
il e ing applica ions shown in he ollowing sec ions.
Induc ance simula o is used as loa ing elemen in RL o
RLC ladde s uc u es. Theo e ical expec a ions a e
suppo ed by simula ion esul s and also by labo a o y
expe imen s.
Fig. 1. P oposed loa ing induc ance simula o based on ECCIIs and DVB
including desc ip ion o beha iou o ac i e elemen s (b own colou ).
Fig. 2. Simula ion esul s o impedance cha ac e is ics (magni ude) o
p oposed induc ance simula o (Fig. 1) in lossless mode while uning B1,2.
A. Recon igu able Fi s -O de High-Pass/In e ing All-
Pass Fil e
P oposed ci cui in Fig. 3 has a pseudo-di e en ial
con igu a ion, which, in acco dance o [8], means ha i has
di e en ial inpu /ou pu e minals, bu inne ci cui i sel is
no ully symme ical. Special ea u es o he in oduced
induc ance simula o in Fig. 1 a e e y use ul o
econnec ion-less econ igu abili y o ans e unc ion in
pseudo-di e en ial i s -o de high-pass/in e ing all-pass
(HP/iAP) il e . These ea u es a e no a ailable i any
s anda d solu ion o simula o o lossless induc ance is
employed as Leq in s uc u e shown in Fig. 3.
Fig. 3. Implemen a ion o he loa ing induc ance simula o in pseudo-
di e en ial-mode econ igu able i s -o de HP/iAP il e (Vinp/ou _s –
symme ical inpu /ou pu ol age).
Di e en ial-mode ans e unc ion ( ull desc ip ion (1)
32
ELEKTRONIKA IR ELEKTROTECHNIKA,ISSN 1392-1215,VOL.23,NO.2,2017
applied) o he ci cui in Fig. 3 has symbolical o m
 
 
_
_
_
3
_ in _ in
_ in 3 1 2
2
_ in _ in
( )
2
2
.
2
ou s
HP iAP
inp s
L L
L
L L
V
K s V
B
s
C R
R B R B B
s
C R
 
 

 

 
 
  

(3)
T ans e unc ion (3) o e s high-pass (HP) esponse, i
B3= 2
 
1 2
2
_ in _ in
( ) 2 ,
HP
L L
s
K s R B B
s
C R


(4)
whe e cu -o (pole) equency is de ined by
 
1 2
12_ in _ in
.
p
L L
R B B
R C



(5)
The easies example o in e ing all-pass (iAP) esponse
is a ailable o R=RL_in ,B1=B2=B1,2 = 1, B3= 3, om (3)
we ob ained simpli ied o m o ans e
_ in
_ in
1/ ( )
( ) 2 .
1/ ( )
L
iAP
L
s C R
K s s C R


(6)
The ollowing ela ion mus be alid o B3i iAP
esponse is eques ed
1 2
32 .
2
B B
B
 
(7)
Fig. 4. Magni ude esponses o he pseudo-di e en ial-mode
econ igu able HP/iAP il e econ igu ed by con ol o Vse _B3 and se e al
examples o uning o he cu -o equency o HP esponse by Vse _B1,2.
Bo h pole/ze o equency has simple o m

p1 = 1/RCL_in .
Also no e ha pole equency can be con olled
elec onically by Vse _B1,2 and ype o ans e unc ion is
econ igu ed by loss pa o induc o simula o (B3gain).
Figu e 4 includes compa ison o expe imen al and simula ed
esul s o he il e om Fig. 3, when wo king esis o was
se R= 1 k. Resul ing aces we e ob ained o ideal cu -o
equency equal o 216 kHz (simula ed 226 kHz, measu ed
227 kHz) ob ained by Vse _B1,2 = 0.1 V, Vse _B3 = 1.95 V (HP
esponse) o 2.15 V in case o iAP esponse ((7) o B3). The
example o

p1 uning in case o he HP esponse by con ol
o B1,2 can be obse ed also in Fig. 4. In measu emen s he
change o Vse _B1,2 be ween 0.1 and 0.5 V ensu es adjus men
o p1 om 227 kHz o 959 kHz, espec i ely.
B. Pseudo-Di e en ial-Mode Second-O de Band-Pass
Fil e
This applica ion is easily a ailable by adding a
capaci ance be ween ou pu e minals as shown in Fig. 5.
T ans e unc ion o ideal RLC ladde s uc u e employing
lossless Leq conside ed in ully-di e en ial o m (1) is
de ined as
2
1
( ) .
1 1
2
BP
eq
sRC
K s
s s
RC L C

 
(8)
R
R
Leq CDVB
1
RL
Ro
50 Ω
50 Ω
OPAMP
RI
AD8138
AD830
DUT
ne wo k analyze
E5071C
Fig. 5. Implemen a ion o he induc ance simula o in second-o de RLC
ladde di e en ial band-pass il e . Schema ic includes expe imen al se up
(Vinp/ou _as – asymme ical ol age; Vinp/ou _s – symme ical ol age).
Conside ing he implemen a ion o lossless Leq_in (i.e.
B3= 2), ans e unc ion (8) changes o
21 2
2_ in _ in
1
( ) ,
1
22
BP
L L
sRC
K s B B
s s RC R C C

 
(9)
whe e cen e (pole) equency and quali y ac o ha e he
ollowing exp essions:
1 2 1,2
1 2
2 2
_ in
_ in
1,2
_ in
_ in
1
2
1,
p p B B B
L
L
L
L
B B
C C
R
B
C C
R
 
 

  

(10)
 
1 2 1,2
1 2
_ in _ in
1,2
_ in _ in
2
2
2.
B B B
L L
L L
B B C
R
Q Q
R C
B C
R
R C
 

  

(11)
No e ha his second-o de BP il e allows uning o he
pole equency wi h heo e ically no e ec on bandwid h,
because BW [Hz] = 1/(4RC), and also change o quali y
33
ELEKTRONIKA IR ELEKTROTECHNIKA,ISSN 1392-1215,VOL.23,NO.2,2017
ac o wi hou change o gain du ing he uning p ocess.
No e ha bo h il e s (Fig. 3 and Fig. 5) ha e +6 dB pass-
band gain (see cons . 2 in (3) and (9)). Howe e ,
expe imen al se up (ou pu di ide ROand RLo ne wo k
analyse ) pe o ms di ision by 2, he e o e, ideal pass-band
gain o he whole sys em is 0 dB.
Fig. 6. Magni ude esponses o he di e en ial-mode second-o de BP
il e du ing uning o he cen e equency.
Compa ison o expe imen al esul s, simula ions, and
heo e ical aces o magni ude and phase esponses o he
pseudo-di e en ial-mode BP il e is gi en in Fig. 6. Passi e
componen alues and ac i e pa ame e s we e se as ollows:
RL_in = 560 ,CL_in =C= 470 pF, R= 1 k,B3= 0 and
B1=B2=B1,2 = 1 (Vse _B1,2 = 1 V). Theo e ical,
expe imen ally es ed, and simula ed BP achie ed p2 = {605,
606, and 596} kHz, wi h BW = {169, 163, and 163} kHz
and Q= {3.6, 3.8, and 3.7} espec i ely. Tuning p ocess
(adjus men o B1,2) can be also obse ed in Fig. 6. In
measu emen s, adjus ing o Vse _B1,2 be ween 0.1 V and 2 V
o e s ange o p2 uning om 199 kHz o 880 kHz. All
de ails a e no ed in igu es. P esen ed expe imen al esul s in
Fig. 4 and Fig. 6 we e ca ied ou using ec o ne wo k
analyse E5071C wi h es se up gi en in Fig. 5. Figu e 7
shows he ab ica ed p o o ype including con e e s om
single-ended o di e en ial mode and ice e sa se ing o
pe o med expe imen al es s.
Fig. 7. Fab ica ed expe imen al p o o ype o pseudo-di e en ial il e .
IV. DISCUSSION AND SUMMARIZATION OF RESULTS
Analysis o discussed induc ance simula o e ealed
ollowing ad an ages: a) possible implemen a ion in
di e en ial applica ions ( loa ing elemen ), b) pseudo-
di e en ial cha ac e o ci cui y (inne g ounded capaci o ),
c) simple elec onic con ollabili y o induc ance alue and
losses including special o m o losses (2) ha allows
in e es ing applica ions. No e ha hese ea u es a e no
simul aneously a ailable in many s anda d solu ions. The
alue o designed induc ance simula o was es ed om
2.63 H o 0.13 H (Vse _B1,2 adjus ed om 0.1 V up o 2.0
V), i.e. unabili y a io is app oxima ely 1:20.
In acco dance o he s a e-o - he-a discussed in Table I,
he i s applica ion example o he designed special
induc ance implemen a ion ( econ igu able i s -o de il e )
ep esen s unique de ice, because up o now
(pseudo)di e en ial-mode econ igu able il e s ha e no
been widely in es iga ed. Ope a ion o he HP/iAP was
e i ied by change o Vse _B3 om 1.95 V o 2.15 V
(HP→iAP). Tuning ange o he pole equency yields
alues om 227 kHz o 959 kHz (Vse _B1,2 se om 0.1 V o
0.5 V). The second example o applica ion, he pseudo-
di e en ial second-o de BP was es ed in equency ange
om 199 kHz o 880 kHz (Vse _B1,2 se om 0.1 V o 2.0 V)
wi h almos cons an bandwid h app oxima ely equal o
165 kHz.
V. CONCLUSIONS
P esen ed loa ing induc ance simula o was es ed in wo
no el applica ions namely pseudo-di e en ial-mode
econ igu able i s -o de HP/iAP il e and second-o de BP
il e de i ed om passi e p o o ypes. Due o limi a ions o
comme cially a ailable de ices used in induc ance
simula o , a ge ed equency ange was in hund eds o kHz.
Expe imen al esul s a e in good ag eemen wi h simula ions
and heo y. P oposed induc ance simula o o e s in e es ing
ea u es in gi en applica ions and special o m o i s losses
(in lossy mode o ope a ion) b ings use ul implemen a ions
also in pseudo-di e en ial-mode oscilla o s. Fu u e po en ial
o di e en ial-mode ci cui s is unde g ea in e es s o many
esea che s. The e o e, we expec u he de elopmen o
hese ci cui s especially wi h econnec ion-less
econ igu a ions.
REFERENCES
[1] O. Casas, R. Pallas-A eny, “Basics o analog di e en ial il e s”,
IEEE T ans. Ins umen a ion and Measu emen , ol. 45, no. 1,
pp. 977–985, 1996. [Online]. A ailable: h p://dx.doi.o g/10.1109/
19.481347
[2] A. A. El-Adawy, A. M. Soliman, H. O. Elwan, “A no el ully
di e en ial cu en con eyo and applica ions o analog VLSI”,
IEEE T ans. Ci cui s and Sys ems – II: Analog and Digi al Signal
P ocessing, ol. 47, no. 4, pp. 306–313, 2000. [Online]. A ailable:
h p://dx.doi.o g/10.1109/82.839666
[3] S. M. Al-Shah ani, “Fully di e en ial second o de il e ”, in P oc.
47 h IEEE In . Midwes Symposium on Ci cui s and Sys ems
(MWSCAS), Hi oshima, Japan, 2004, pp. 299–301. [Online].
A ailable: h p://dx.doi.o g/10.1109/MWSCAS.2004.1354353
[4] P. Beg, I. A. Khan, S. Maheshwa i, M. A. Siddiqi, “Digi ally
p og ammable ully di e en ial il e ”, Radioenginee ing, ol. 20,
no. 4, pp. 917–925, 2011.
[5] R. Beg, S. Maheshwa i, M. A. Siddigi, “Digi ally con olled ully
di e en ial ol age- and ansadmi ance-mode biquad a ic il e ”,
IET Ci cui s, De ices and Sys ems, ol. 7, no. 4, pp. 193–203, 2013.
[Online]. A ailable: h p://dx.doi.o g/10.1049/ie -cds.2012.0244
[6] M. A. Ib ahim, H. Kun man, “A no el high CMRR high inpu
impedance di e en ial ol age-mode KHN-biquad employing DO-
DDCCs”, AEU – In e na ional Jou nal o Elec onics and
Communica ions, ol. 58, no. 6, pp. 429–433, 2004. [Online].
34
ELEKTRONIKA IR ELEKTROTECHNIKA,ISSN 1392-1215,VOL.23,NO.2,2017
A ailable: h p://dx.doi.o g/10.1078/1434-8411-54100266
[7] A. K. Singh, P. Kuma , “A no el ully di e en ial cu en mode
uni e sal il e ”, in P oc. 57 h In . Midwes Symposium on Ci cui s
and Sys ems (MWSCAS), Texas, USA, 2014, pp. 579–582. [Online].
A ailable: h p://dx.doi.o g/10.1109/MWSCAS.2014.6908481
[8] J. Ko on, N. He encsa , O. Sladok, J-W. Ho ng, “Pseudo-di e en ial
second-o de band- ejec il e using cu en con eyo s”, AEU -
In e na ional Jou nal o Elec onics and Communica ions, ol. 70,
no. 6, pp. 814–821, 2016. [Online]. A ailable: h p://dx.doi.o g/
10.1016/j.aeue.2016.03.009
[9] J. Ko on, N. He encsa , J. W. Ho ng, “Di e en ial second-o de
ol age-mode all-pass il e using cu en con eyo s”, Elek onika i
Elek o echnika, ol. 22, no. 5, pp. 52–57, 2016. [Online]. A ailable:
h p://dx.doi.o g/10.5755/j01.eie.22.5.16344
[10] M. A. Ib ahim, S. Minaei, H. Kun man, “DVCC based di e en ial-
mode all-pass and no ch il e s wi h high CMRR”, In . Jou nal o
Elec onics, ol. 93, no. 4, pp. 231–240, 2006. [Online]. A ailable:
h p://dx.doi.o g/10.1080/00207210600562181
[11] M. S. Ansa i, G. S. Soni, “Digi ally-p og ammable ully-di e en ial
cu en -mode i s -o de LP, HP and AP il e sec ions”, in P oc. In .
Con . Signal P opaga ion and Compu e Technology (ICSPCT),
Ajme , India, 2014, pp. 524–528. [Online]. A ailable:
h p://dx.doi.o g/10.1109/ICSPCT.2014.6884963
[12] J. W. Ho ng, C. M. Wu, N. He encsa , “Fully di e en ial i s -o de
allpass il e s using a DDCC”, Indian J Eng Ma e Sci, ol. 21, no. 4,
pp. 345–350, 2014.
[13] I. A. Khan, M. I. Masud, S. A. Moiz, “Recon igu able ully
di e en ial i s o de all pass il e using digi ally con olled CMOS
DVCC”, in P oc. 8 h IEEE GCC Con . and exhibi ion (GCCCE),
Musca , Oman, 2015, pp. 1–5. [Online]. A ailable:
h p://dx.doi.o g/10.1109/IEEEGCC.2015.7060082
[14] N. He encsa , J. Je abek, J. Ko on, K. V ba, S. Minaei, I. C. Gokna ,
“Pole equency and pass-band gain unable no el ully-di e en ial
cu en -mode all-pass il e ”, in P oc. IEEE In . Symposium on
Ci cui s and Sys ems (ISCAS), Lisbon, Po ugal, 2015, pp. 2668–
2671. [Online]. A ailable: h p://dx.doi.o g/10.1109/ISCAS.
2015.7169235
[15] R. So ne , J. Je abek, N. He encsa , T. Zak, W. Jaikla, K. V ba,
“Modi ied cu en di e encing uni and i s applica ion o
elec onically econ igu able simple i s -o de ans e unc ion”,
Ad ances in Elec ical and Compu e Enginee ing, ol. 15, no. 1,
pp. 3–10, 2015. [Online]. A ailable: h p://dx.doi.o g/10.4316
/AECE.2015.01001
[16] R. So ne , J. Je abek, L. Langhamme , J. Polak, N. He encsa ,
R. P okop, J. Pe zela, W. Jaikla, “Compa ison o wo solu ions o
quad a u e oscilla o s wi h linea con ol o equency o oscilla ion
employing mode n comme cially a ailable de ices”, Ci cui s,
Sys ems and Signal P ocessing, ol. 34, no. 11, pp. 3449–3469,
2015. [Online]. A ailable: h p://dx.doi.o g/10.1007/s00034-015-
0015-7
35