Z-Copy Controlled-Gain Voltage Differencing Current

ELEKTRONIKA IR ELEKTROTECHNIKA, ISSN 1392–1215, VOL. 20, NO. 6, 2014

1Abstract—A modified version of voltage differencingcurrent conveyor (VDCC) and its performance in detail ispresented in this paper. Modified VDCC, so-called z-copycontrolled gain voltage differencing current conveyor (ZC-CG-VDCC), offers interesting features from adjustability point ofview. The active element allows independent electronic controlof three adjustable parameters: intrinsic resistance of currentinput terminal, transconductance and current gain of theoutput stage which is not possible in case of conventionalVDCC. The characteristics of proposed CMOS implementationdesigned using TSMC LO EPI 0.18 m technology processparameters are shown and discussed. Simple application inreconfigurable reconnection-less first-order voltage-modemultifunctional filter is shown and verified by SPICEsimulations and experimentally. The filter tuning and change ofthe transfer function type is allowed by the controllableparameters of the ZC-CG-VDCC.

Index Terms—Electronic control, current conveyor, currentgain, first order, intrinsic resistance, multifunctional filter,reconfiguration, transconductance, voltage differencing currentconveyor, voltage-mode, z-copy, ZC-CG-VDCC.

I. INTRODUCTION

Active elements [1] with more than one controllableparameter are very important for technical progress in thisfield, because they allow more effective electronic control,

Manuscript received January 13, 2014; accepted April 9, 2014.Research described in the paper was supported by Czech Science

Foundation project under No. 14-24186P, by internal grant No. FEKT-S-14-2281, and project Electronic-biomedical co-operation ELBIC M00176.The support of the project CZ.1.07/2.3.00/20.0007 WICOMT, financedfrom the operational program Education for competitiveness, is gratefullyacknowledged. The described research was performed in laboratoriessupported by the SIX project; the registration numberCZ.1.05/2.1.00/03.0072, the operational program Research andDevelopment for Innovation. Dr. Herencsar was supported by the projectCZ.1.07/2.3.00/30.0039 of the Brno University of Technology.

increasing variability in applications, simple circuit designand simple circuit structure. Frequently discussed activeelements use principles based on electronic control of theintrinsic resistance (Rx) of the current input terminal x [2] (inthe frame of current conveyor [3]) and control of thetransconductance section (gm) [4]. Active elements withpossibility of current gain (B) control were presented bySurakampontorn et al. [5] and Fabre et al. [6]. However,only the current gain control is realized.

Some active elements that combine two externallycontrollable parameters (by bias voltage or current) werealready discussed in applications of analog circuits andsystems [7]–[9]. Minaei et al. [7] proposed current conveyorwith adjustable properties i.e. adjustable B between x and zterminals and adjustable intrinsic resistance of the currentinput terminal x. Marcellis et al. [8] introduced modifiedconveyor with controllable features of voltage gain betweeny a x and current gain between x and z terminals. Kumngernet al. [9] also combined Rx and B control in their version oftranslinear current conveyor.

Several combined active elements, based ontransconductance section (OTA) [1], [4] and currentconveyor of second generation (CCII) [2], [3], were alreadyproposed. Typical examples of active elements with two-parameter control are some modifications of the very knowncurrent differencing transconductance amplifier (CDTA) [1],[10], where Rx and gm control is implemented by DC biascurrents [11], [12]. For example, the current conveyortransconductance amplifier (CCTA) [1], [13] also utilizesindependent Rx and gm control in some of its modifications[14]. One modification of CCTA [15] also employs currentgain control, where current conveyor with gain-adjustableproperties was used. Controllable current gain in frame ofcurrent conveyor [5], [6] seems to be an interesting and

Z-Copy Controlled-Gain Voltage DifferencingCurrent Conveyor: Advanced Possibilities in

Direct Electronic Control of First-Order FilterR. Sotner1, N. Herencsar2, J. Jerabek2, R. Prokop3, A. Kartci4, T. Dostal5, K. Vrba2

1Department of Radio Electronics, Faculty of Electrical Engineering and Communication,Brno University of Technology, Technicka 12, Brno, 616 00, Czech Republic

2Department of Telecommunications, Faculty of Electrical Engineering and Communication,Brno University of Technology, Technicka 12, Brno, 616 00, Czech Republic

3Department of Microelectronics, Faculty of Electrical Engineering and Communication,Brno University of Technology, Technicka 10, Brno, 616 00, Czech Republic

4Department of Electronics and Communication Engineering, Faculty of Electrical & Electronics,Yildiz Technical University, Davutpasa Mah., 34220-Esenler, Istanbul, Turkey

5Department of Electrical Engineering and Computer Science, College of Polytechnics Jihlava,Tolsteho 16, Jihlava 586 01, Czech Republic

[email protected]

http://dx.doi.org/10.5755/j01.eee.20.6.7272

77


valuable advantage. Active elements having this advantageattained many innovative modifications [16], [17].

The main aim of this paper is a design of an enhancedactive element with useful and feasible controllable features.A voltage differencing current conveyor (VDCC) belongs tofamily of novel hybrid elements presented by Biolek et al.[1]. In this contribution the VDCC, used as main core of theproposed new active device, is presented as z-copy variantwith controllable parameters. We refer this modification asz-copy controlled gain voltage differencing current conveyor(ZC-CG-VDCC). Hitherto published works have alreadydiscussed so-called differential voltage current conveyor(DVCC) [1], [18]–[21]. Nevertheless, both elements (VDCCand DVCC) have different behaviour and also differentblock structure that inheres from basic behaviour. TheDVCC has two differential voltage input terminals y andrealizes difference of two voltages [18]–[21]. The rest of theconception is identical to common current conveyor [2], [3].One current input terminal x and current output terminal z(or multiple terminals z) are available. In comparison todiscussed DVCC, the VDCC also consists oftransconductance section (OTA) [1], [4] and offersadditional auxiliary terminal for more universality of suchelement. Very interesting active elements, which belong tothis family, were also proposed by Soliman [22] underdesignation pseudo-differential current conveyors (PDCCs).For example, the CCTA [13]–[15] utilizes same types ofsub-blocks (CCII and OTA) as VDCC, however in reverseorder of interconnection. This different order ofinterconnection also brings interesting features inapplications. However, any of above discussed activeelements and approaches do not allow control of threeparameters within the frame of one active device as ispresented in this paper. This approach allows construction ofvery simple applications with minimum number of passiveelements.

II. Z-COPY CONTROLLED-GAIN VOLTAGE DIFFERENCINGCURRENT CONVEYOR

Proposed active element, so-called z-copy controlled gainvoltage differencing current conveyor (ZC-CG-VDCC) isshown in Fig. 1. This element was derived from basictheoretical concept of VDCC [1]. The conventional VDCCconsist of a transconductance amplifier [1], [4] connected tothe y terminal of classical second generation currentconveyor [3]. Important fact is that only transconductancecontrol is available in frame of conventional VDCC. Ourmodification allows simultaneous and mutually independentcontrol of three important parameters, i.e. gm, Rx of currentinput terminal x in frame of the CCII section [2], and also Bbetween x and z terminals of the CCII section [5]–[9].Behavioural model consists of the transconductor OTA-DISO (differential input and single output) andelectronically controllable CCII (ECCII) [5]–[7], [9]. TheOTA section allows gm control and ECCII section realizescontrol of Rx and B.

Symbol of ZC-CG-VDCC in Fig. 1(a) utilizes highimpedance voltage differencing inputs p, n, auxiliaryterminals z_TA, zc_TA (outputs of transconductance

section), high impedance positive and negative currentoutputs of section of current conveyors zp, zn, low-impedance current input / voltage output x (current conveyorpart) and three terminals for external control of B, intrinsicresistance, and transconductance by bias currents. Followingequations describe inter-terminal relations: Vx = Vz_TA+RxIx,Iz_TA = –Iz_TA = Izc_TA = (Vp–Vn)gm, Izp = IxB, Izn = –IxB.

Figure 1(b) explains behaviour of the proposed device indetails and its possible block diagram is given in Fig. 1(c).Such active element seems to be complex, but internalCMOS topology is not challenging, see Fig. 2. Basic blockstructure form Fig. 1(c) was taken into account for design ofCMOS realization in Fig. 2. There are three important parts(transconductor, current conveyor of second generation andadjustable current amplifier). The first part is thetransconductance amplifier [1], [4], [23] with differentialNMOS pair connected to a voltage input of CMOS currentconveyor. Intrinsic resistance control was performed inframe of the current conveyor section [2], [23], which isseparated from the last block forming adjustable currentamplifier [24]. The reason for this subdivision is simple.Bias control of intrinsic resistance in frame of currentconveyor with current amplifier section influences at leastdependence of current gain on control bias currentsignificantly as was discussed in [25]. Therefore,independent current conveyor and independent bias currentserves for intrinsic resistance controlling purposes.

The transconductance of the OTA section is given byideal equation [23]

1,2_

1,22 ,M

m set gm PnM

Wg I K

L (1)

where constant 2 is given by current mirror gain (see Fig. 2).Intrinsic resistance of current input x has expression [23]

11,12 13,14_ _

11,12 13,14

1 ,xM M

set Rx Pn set Rx PpM M

RW W

I K I KL L

(2)

and adjustable current gain has form [24]

2 2

_ _,

2b b

set B set B

NI IB

I I (3)

where N = 2 (see Fig. 2). Proposed CMOS model wassimulated and analysed with TSMC LO EPI 0.18 mtechnology process parameters [26], where fabricationconstants (given by gate-oxide capacitance and mobility ofcarriers) have approximate values of KPn = 170.4 A/V2 andKPp = 35.7 A/V2.

III. SPICE SIMULATION RESULTS OF THE ZC-CG-VDCCMain parameters of the proposed ZC-CG-VDCC with

power supply voltages 1 V are given in following figures.Gain control of current from x to z terminals was verified byadjusting of bias current Iset_B from 20 A to 100 A in rangeof B from 3.76 to 0.36 (Fig. 3).

78


zc_TA

p

x

Ip = 0Vp

Vx

Izc_TA

Vz_TA

Vn nIn = 0

gm(Iset_gm)

Izp Vzpzp

Rx

IxIz_TA

z_TA

Vzc_TA

Izn

znVzn

ZC-CG-VDCC

B(Iset_B)

Rx(Iset_Rx) p

z_TA

ZC-CG-VDCC

(Vp – Vn).gm = Iz_TA = Izc_TA

n

1

xVx = Vz_TA + Rx.Ix

Izp zpIx.B = IzpIx

RX

zc_TA

Izc_TA

Izn

-Ix.B = Izn

zn

Iz_TA

ECCII

+Z

Y

X

OTAgm

p

z_TA

n

x

zpRx

zn-Z

zc_TA

gm(Iset_gm)

B(Iset_B)

Rx(Iset_Rx)

a) b) c)Fig. 1. Proposed ZC-CG-VDCC with independent control of three parameters: a) symbol, b) behavioral model, c) possible block conception.

Fig. 2. CMOS realization of proposed ZC-CG-VDCC.

Selected transfers for B = 3, 2, 1, 0.5 are shown in Fig. 3(DC transfer characteristic and frequency response).

a)

b)Fig. 3. Transfer characteristics of controlled current amplification forselected values of current gain: a) DC transfers, b) AC frequencyresponses.

Linear dynamical range of input current (IX) is almost100 A and bandwidth 39 MHz for B = 3. The secondimportant adjustable parameter of presented active element

is transconductance. Bias control of Iset_gm from 10 A to150 A allows changes of gm from 255 S to 1 919 S.Dynamical range of Vp is approximately 100 mV andbandwidth 505 MHz for gm = 1.5 mS. Characteristics in DCand AC domain are shown in Fig. 4 in detail for threeselected values (0.5, 1.0 and 1.5 mS) of gm. DCcharacteristic of voltage gain between z_TA and x port isshown in Fig. 5(a).

a)

b)Fig. 4. Transconductance characteristics for selected values of gm: a) DCtransfers, b) AC frequency responses.

79


Figure 5(b) shows dependence of Rx on Iset_Rx. Inputresistance is controllable from 2.53 k to 451 by Iset_Rx

adjusted from 10 to 150 A. Important parameters of theproposed ZC-CG-VDCC model are summarized in Table I.Notes in Fig. 3–Fig. 5 mean information for connection ofremaining terminals for presented set of analyses.

a)

b)Fig. 5. Important characteristics of the current conveyor part (Rx terminal):a) DC transfer between z_TA and x terminal, b) dependence of Rx on Iset_Rx.

IV. APPLICATION EXAMPLE:RECONFIGURABLE FIRST-ORDER MULTIFUNCTION FILTER

Controllable features of proposed active device can beused in so-called reconfigurable reconnection-less tunablemultifunctional filter (no change of output or input terminalor change of structure is required for change of the transferfunction [27] – electronic control allows contactlessreconfiguration) very beneficially. These solutions were notstudied in detail in the past and our initial experience showsthat such active elements like ZC-CG-VDCC with variety ofcontrollable possibilities are very useful for their synthesis.

zc_TA

p

xn

gm

zp

Rx

Rx

-z_TA zn

ZC-CG-VDCC

C

VOUTVINP

B

Fig. 6. Reconnection-less reconfigurable and tunable low-pass and all-passfilter.

Proposed solution is shown in Fig. 6. Note that circuit inFig. 6 requires z_TA terminal with opposite (negative)polarity. It is indicated by dashed line in CMOS structure inFig. 2. Transfer function (TF) of the circuit in Fig. 6 hasform

1( ) ,m x mOUT

INP m

Bg sC R gVK s

V Bg sC

(4)

where zero and pole frequencies (fz, fp) are given as:z = Bgm/(C(Rxgm–1)) and p = Bgm/C. It is clearly seen thatcurrent gain B serves for simultaneous control of fp,z. The Rx

configures type of the transfer function electronicallyindependently on other parameters. The all-pass (AP) filterresponse is available in case when gmRx = 2 and its TF has aform

( ) ,OUT mAP

INP m

V Bg sCK s

V Bg sC

(5)

TABLE I. SUMMARIZATION OF IMPORTANT FEATURES OF THEZC-CG-VDCC CMOS MODEL.

Controllable parametersparameter tested range of adjusting

current gain (B [-]) 0.36 – 3.76 (Iset_B = 100 A – 20 A)transconductance (gm [S]) 255 – 1 919 (Iset_gm = 10 A – 150 A)

intrinsic resistance (Rx [k]) 2.53 – 0.451 (Iset_Rx = 10 A – 150 A)DC performances (Iset_gm = Iset_Rx = Iset_B = 100 A) .TF analysis

parameter valueIzp/Ix [-] 0.36Izn/Ix [-] 0.35

Iz_TA/Vp (gm)[S] 1 517Vz_TA/Vx [-] 0.98

Rp, n [] 1E20Rz_TA, zc_TA [k] 34.6

Rx [] 533Rzp [k] 55.0Rzn [k] 53.1

AC performances (Iset_gm = Iset_Rx = Iset_B = 100 A)parameter value

Rz_TA (Rzc_TA) [k] > 35 for Iset_gm ≤ 100 A (f < 10 MHz)Rzp, Rzn [k] > 50 for Iset_B ≤ 100 A (f < 1 MHz)

Cp, n [fF] 30Cz_TA, Czc_TA [fF] 110

Czp [fF] 120Czn [fF] 190

And if gmRx = 1, the low-pass (LP) filter response isobtained

( ) .OUT mLP

INP m

V BgK s

V Bg sC

(6)

Special type of TF so-called inverting direct transfer(iDT) is available for gmRx = 2 and B = 0. In theseconditions the circuit works as direct connection (constantmagnitude and phase response) between input and outputterminal. Pure direct transfer (non-inverting) is available forgmRx 0 together with any value of positive gain B.

We provided simulations of the circuit in Fig. 6 withproposed CMOS model (Fig. 2) and experimentalverifications with behavioural model of ZC-CG-VDCCbased on commercially available devices called diamondtransistor (DT) OPA860 and multiplier EL2082 (ECCII-),see Fig. 7. Results presented in further text were gained for

80


C = 470 pF and gm = 1 mS, see comments in figures (figurecaptions) for obtained values and setting of parameters insimulations and experiments. Supply voltage of thebehavioral model was 5 V (1 V for CMOS model).

Fig. 7. Behavioral model of the ZC-CG-VDCC in proposed reconfigurablefiltering application employing commercially available active devices.

Frequency responses of the TF change between AP, LP,DT and iDT were recorded by network analyser E5071C(fmin = 9 kHz, Pinp = -15 dBm/50 ), see Fig. 8–Fig. 11.

Fig. 8. All-pass filter response for gm = 1 mS, Rx = 2 k and B = 1.

Fig. 9. Low-pass filter response for gm = 1 mS, Rx = 1 k and B = 1.

Phase responses in Fig. 12 document electronicreconfiguration between iDT, DT transfer and LP and APresponse for specific set of Rx and B values, see details inFig. 12 where also comparison of ideal, simulated (proposedCMOS model of the ZC-CG-VDCC) and measured

(behavioural model) traces is given. Validity of thebehavioural model is supposed approximately to 1 MHz.Features of the CMOS model (Rx, B) do not allow operationof the filter (Fig. 6) in iDT and DT regime.

Fig. 10. Direct transfer response for gm = 1 mS, Rx = 0 k and B = 1.

Fig. 11. Inverting direct transfer response (gm = 1 mS, Rx = 2 k andB = 0).

Fig. 12. Reconfiguration between iDT, DT, LP and AP (phase responses).

Transient response (oscilloscope Rigol DS1204B) of theAP filter is shown in Fig. 13 (finp = 313 kHz, AP has thesame setting as we give in caption of Fig. 8). Tuning featuresfor AP and LP responses are shown in Fig. 14 and Fig. 15.Ideal values of pole/zero frequencies (fp,z) are 169, 339 and667 kHz (B = 0.5, 1, 2). Values of fp,z, obtained fromsimulations were 187 kHz, 350 kHz and 696 kHz andexperiments yield values 166 kHz, 313 kHz and 610 kHz

81


(see also Fig. 14).

Fig. 13. Transient response of the AP filter for finp = 313 kHz (gm = 1 mS,Rx = 2 k and B = 1).

-180

-160

-140

-120

-100

-80

-60

-40

-20

0

20

1.0E+04 1.0E+05 1.0E+06 1.0E+07f [Hz]

j[deg]

measured: f p,z = 166 kHz; simulated: f p,z = 187 kHz; ideal: f p,z = 169 kHzB = 0.5 (I set_B = 93 µA)

R x = 2 kΩ (I set_Rx = 13.3 µA)g m = 1 mS (I set_gm = 54 µA)

ideal

measured (behavioral model)

simulated(CMOS model)

measured: f p,z = 313 kHzsimulated: f p,z = 350 kHzideal: f p,z = 339 kHzB = 1.0 (I set_B = 81 µA)

measured: f p,z = 610 kHzsimulated: f p,z = 696 kHzideal: f p,z = 667 kHzB = 2.0 (I set_B = 58 µA)

Fig. 14. Tuning of the AP filter (phase responses).

Fig. 15. Tuning of the LP filter (magnitude responses).

V. CONCLUSIONS

Our work is focused on design of modification of thevoltage differencing current conveyor, proposal of its modeland example of its useful features in simple application. Themost important advantages of proposed active element areavailability of three types of independent electronic controland useful z-copy technique. Range of the B control of theCMOS model was verified between 0.36 and 3.76 (Iset_B

from 100 A to 20 A), control of the gm value between255 S and 1 919 S (Iset_gm from 10 A to 150 A) and Rx

value in range from 2.53 k to 0.451 k (Iset_Rx from 10 Ato 150 A). Frequency features allow operation of CMOS

simulation model to tens of MHz. Bandwidth (3 dB) of theZC-CG-VDCC model is determined by current amplifierblock, where minimal value 39 MHz was obtained for B = 3,see Fig. 3(b). Further details are summarized in Table I.Proposed active element was implemented in simpleelectronically reconfigurable reconnection-less first-ordermultifunctional filtering structure working in voltage-modewhich features were verified in frequency band of hundredsof kHz by Spice simulations and experimentally withbehavioural model of the proposed active device employingcommercially available devices. Electronic control allowschange of the transfer type (direct transfer, inverting directtransfer, all-pass and low-pass response) and tuning of thefp,z frequency (even independent control of fz). Tuning wastested for three values of B (0.5, 1, 2) that results insimulated fp,z (187, 350, 696 kHz). Measurements provide166 kHz, 313 kHz and 610 kHz (Fig. 14). Behavioural andCMOS models of the ZC-CG-VDCC represent expectedbehaviour of filtering application and confirm ourassumptions. ZC-CG-VDCC seems to be interesting choicefor circuit synthesis and possible fabrication.

REFERENCES

[1] D. Biolek, R. Senani, V. Biolkova, Z. Kolka, “Active elements foranalog signal processing: classification, review and new proposals”,Radioengineering, vol. 17, no. 4, pp. 15–32, 2008.

[2] A. Fabre, O. Saaid, F. Wiest, C. Boucheron, “High frequencyapplications based on a new current controlled conveyor”, IEEETrans. on Circuits and Systems - I, vol. 43, no. 2, pp. 82–91, 1996.

[3] A. Sedra, K. C. Smith, “A second generation current conveyor and itsapplications”, IEEE Trans. Circuit Theory, vol. CT-17, no. 2,pp. 132–134, 1970. [Online]. Available: [Online]. Available:http://dx.doi.org/10.1109/TCT.1970.1083067

[4] R. L. Geiger, E. Sanchez-Sinencio, “Active filter design usingoperational transconductance amplifiers: a tutorial”, IEEE Circ. andDevices Magazine, vol. 1, pp. 20–32, 1985. [Online]. Available:http://dx.doi.org/10.1109/MCD.1985.6311946

[5] W. Surakampontorn, W. Thitimajshima, “Integrable electronicallytunable current conveyors”, IEE Proc.-G, vol. 135, no. 2, 1988,pp. 71–77. [Online]. Available: http://dx.doi.org/10.1049/ip-g-1.1988.0010

[6] A. Fabre, N. Mimeche, “Class A/AB second-generation currentconveyor with controlled current gain”, Electronics Letters, vol. 30,no. 16, pp. 1267–1268, 1994. [Online]. Available:http://dx.doi.org/10.1049/el:19940878

[7] S. Minaei, O. K. Sayin, H. Kuntman, “A new CMOS electronicallytunable current conveyor and its application to current-mode filters”,IEEE Trans. on Circuits and Systems - I, vol. 53, no. 7, pp. 1448–1457, 2006.

[8] A. Marcellis, G. Ferri, N. C. Guerrini, G. Scotti, V. Stornelli, A.Trifiletti, “The VGC-CCII: a novel building block and its applicationto capacitance multiplication”, Analog Integrated Circuits andSignal Processing, vol. 58, no. 1, pp. 55–59, 2009. [Online].Available: http://dx.doi.org/10.1007/s10470-008-9213-6

[9] M. Kumngern, S. Junnapiya, “A sinusoidal oscillator usingtranslinear current conveyors”, in Proc. Asia Pacific Conf. onCircuits and Systems (APPCAS 2010), Kuala Lumpur, 2010, pp.740–743. [Online]. Available: http://dx.doi.org/10.1109/APCCAS.2010.5774754

[10] A. U. Keskin, D. Biolek, E. Hancioglu, V. Biolkova, “Current-modeKHN filter employing current differencing transconductanceamplifiers”, AEU – Int. Journal of Electronics and Communications,vol. 60, no. 6, pp. 443–446, 2006. [Online]. Available:http://dx.doi.org/10.1016/j.aeue.2005.09.003

[11] W. Jaikla, A. Lahiri, “Resistor-less current-mode four-phasequadrature oscillator using CCCDTAs and grounded capacitors”,AEU – Int. Journal of Electronics and Communications, vol. 66,no. 3, pp. 214–218, 2011. [Online]. Available:http://dx.doi.org/10.1016/j.aeue.2011.07.001

[12] Ch. Sakul, W. Jaikla, K. Dejhan, “New resistorless current-mode

82


quadrature oscillators using 2 CCCDTAs and grounded capacitors”,Radioengineering, vol. 20, no. 4, pp. 890–896, 2011.

[13] R. Prokop, V. Musil, “Modular approach to design of modern circuitblocks for current signal processing and new device CCTA”, in Proc.Conf. on Signal and Image Processing (IASTED), Anaheim, 2005,pp. 494–499.

[14] M. Siripruchyanun, W. Jaikla, “Current controlled current conveyortransconductance amplifier (CCCCTA): a building block for analogsignal processing”, Electrical Engineering Springer, vol. 90, no. 6,pp. 443–453, 2008. [Online]. Available: http://dx.doi.org/10.1007/s00202-007-0095-x

[15] R. Sotner, J. Jerabek, R. Prokop, K. Vrba, “Current gain controlledCCTA and its application in quadrature oscillator and directfrequency modulator”, Radioengineering, vol. 20, no. 1, pp. 317–326, 2011.

[16] R. Sotner, J. Jerabek, N. Herencsar, Z. Hrubos, T. Dostal, K. Vrba,“Study of adjustable gains for control of oscillation frequency andoscillation condition in 3R-2C oscillator”, Radioengineering, vol. 21,no. 1, pp. 392–402, 2012.

[17] J. Jerabek, J. Koton, R. Sotner, K. Vrba, “Adjustable band-pass filterwith current active elements: two fully-differential and single- endedsolutions”, Analog Integrated Circuits and Signal Processing,vol. 74, no. 1, pp. 129–139, 2013. [Online]. Available:http://dx.doi.org/10.1007/s10470-012-9942-4

[18] S. Minaei, M. A. Ibrahim, “General configuration for realizingcurrent-mode first-order all-pass filter using DVCC”, Int. Journal ofElectronics, vol. 92, no. 6, pp. 347–356, 2005. [Online]. Available:http://dx.doi.org/10.1080/00207210412331334798

[19] S. Maheshwari, “A canonical voltage-mode-controlled VM-APS withgrounded capacitors”, Circuits Systems and Signal Processing,vol. 27, no. 1, pp. 123–132, 2008. [Online]. Available:

http://dx.doi.org/10.1007/s00034-008-9015-1[20] S. Minaei, E. Yuce, “Novel voltage-mode all-pass filter based on

using DVCCs”, Circuits Systems and Signal Processing, vol. 29,no. 3, pp. 391–402, 2010. [Online]. Available: http://dx.doi.org/10.1007/s00034-010-9150-3

[21] J. W. Horng, “DVCCs based high input impedance voltage-modefirst-order allpass, highpass and lowpass filters employing groundedcapacitor and resistor”, Radioengineering, vol. 19, no. 4, pp. 653–656, 2010.

[22] A. M. Soliman, “Wide dynamic range CMOS pseudo-differentialcurrent conevyors: CMOS realizations and applications”, CircuitsSystems and Signal Processing, vol. 32, no. 2, pp. 477–497, 2013.[Online]. Available: http://dx.doi.org/10.1007/s00034-012-9478-y

[23] J. Baker, CMOS Circuit Design, Layout and Simulation. Wiley-IEEEPress, West Sussex, 2005, p. 1039.

[24] W. Surakampontorn, K. Kumwachara, “CMOS-based electronicallytunable current conveyor”, Electronics Letters, vol. 28, no. 14.,pp. 1316–1317, 1992. [Online]. Available: http://dx.doi.org/10.1049/el:19920836

[25] R. Sotner, J. Jerabek, N. Herencsar, T. Dostal, K. Vrba,“Electronically adjustable modification of CFA: Double CurrentControlled CFA (DCC-CFA)”, in Proc. of the 35th Int. Conf. onTelecommunications and Signal Processing (TSP 2012), Prague,2012, pp. 401–405.

[26] MOSIS parametric test results of TSMC LO EPI SCN018 technology.[Online]. Available: ftp://ftp.isi.edu/pub/mosis/vendors/tsmc-018/t44e_lo_epi-params.txt

[27] R. Sotner, J. Jerabek, B. Sevcik, T. Dostal, K. Vrba, “Novel solutionof notch/all-pass filter with special electronic adjusting of attenuationin the stop band”, Elektronika ir Elektrotechnika, vol. 17, no. 7,pp. 37–42, 2011.

83

Documents

Z-Copy Controlled-Gain Voltage Differencing Current