Download OPTIMIZATION OF CURRENT MODE LOGIC CIRCUITS

MONIKA CHOUDHARY et al.
Volume 3 Issue 3: 2015
Citation: 10.2348/ijset06150825
Impact Factor- 3.25
ISSN (O): 2348-4098
ISSN (P): 2395-4752
OPTIMIZATIONOFCURRENTMODELOGICCIRCUITSOSCILLATORUSING
CURRENTDIFFERENCINGBUFFERAMPLIFIER
1MONIKACHOUDHARY,2SHARAVANBISHNOI,3NIDHISHTIWARI
1M.Tech.Scholar,JagannathUniversity,Jaipur,Email:[email protected]
3AssistantProfessor,DepartmentofElectronics&CommunicationEngineering,JagannathUniversity,Jaipur
ABSTRACT
AnewimprovedCMOSconfigurationofCDBAispresentedprovidinglowinputimpedancesatportspandn,veryhighoutput
impedanceatportz,agoodlinearityandhighinput/outputgainratioforcurrenttransfer.TheofferedCDBAcontainsonly
MOStransistorsandisdesignedtobeimplementedinCMOStechnology.TodemonstratetheperformanceoftheCDBAcircuit,
afirstorderall‐passfilterwaschosen.ThenextsectionsincludethePSPICEsimulationsfiltercharacteristicsandtheoscillator
characteristic. The simulations show that the proposed CDBA circuit exhibits a very good performance and the results
obtainedforthefilterareingoodagreementwiththeory.
IndexTerms‐CMOS,CDBA.
1. INTRODUCTION
Current mode circuits are designed using current mode
active elements as basic building blocks. Moreover
following building blocks have been developed for
current mode circuit design: first generation current
conveyors (CCI), second generation current conveyors
(CCII), third generation current conveyors (CCIII),
operational transconductance amplifier (OTA), current
feedback amplifier (CFA), differential difference current
conveyor(DDCC),currentdifferencingbufferedamplifier
(CDBA), current differencing transconductance amplifier
(CDTA),voltagedifferencingtransconductanceamplifier
(VDTA) [6‐11]. Understanding of the design and
functionalityaspectsofthesecurrentmodecircuitswould
help us in development of new such circuits in the
presentresearchwork.
Currentdifferencingbufferedamplifier(CDBA):CDBAisa
multi‐terminal active component with two differential
currentinputsandtwovoltageoutputs.Itisderivedfrom
thecurrentfeedbackamplifier(CFA).Itcanberealizedby
acascadeconnectionofacurrentsubtractorandavoltage
follower.
International Journal of Science, Engineering and Technology- www.ijset.in
Figure1:a)Currentdifferencingbufferamplifiersymbol
b)EquivalentcircuitofCDBA
2. PROPOSEDWORK
Pertaining to current mode circuits, adequate references
of primary level research have been available in
literature. A circuit simulating a second generation
positive and negative current conveyor(CCII) using four
operational amplifiers is reported in literature. This
circuit gives low tracking error. The architecture of first
and second generation current conveyor (CCI and CCII
respectively) is presented and an amplifier is designed
using secondgeneration current conveyor. The designed
amplifierthroughCCII+providesbettergainwithhigher
accuracy. A novel CMOS low‐voltage and low‐power
positive second‐generation current conveyor (CCII+) is
proposed.Itusestwon‐channeldifferentialpairsinstead
of the complementary differential pairs; i.e. (n‐channel
and p‐channel), to realize the input stage. This solution
allows almost a rail‐to‐rail input and output operation;
also it reduces the number of current mirrors needed in
theinputstage.AnewBiCMOSCCIIandCCCII,capableof
operateatlowvoltage(±0.5V)andhavingwidedynamic
rangewithachievedhighbandwidthhavebeenproposed.
The structures have been found to be insensitive to the
threshold voltage variations. Two different current
differencing buffered amplifiers (CDBA)‐based synthetic
floatinginductancecircuitsusinggroundedcapacitorare
introduced. They are fully integrable and provide the
advantages of electronic tuning.A second order all‐pass
and notch filter has been described using current
conveyors in. The circuit uses only two current
conveyors, one operational amplifier/CFA, four resistors
andtwogroundedcapacitors.Thefilteralsodisplayslow
incremental parameter sensitivities. CDBA, current
differencingbufferedamplifierisintroducedinwhichisa
multi‐terminalactivecomponentwithtwoinputsandtwo
outputs.TheCDBAissimplifyingtheimplementation,free
fromparasiticcapacitancesanditisabletooperateinthe
frequency range of more than hundreds of MHz. Active
frequency filters and oscillators for applications in the
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MONIKA CHOUDHARY et al.
Volume 3 Issue 3: 2015
Citation: 10.2348/ijset06150825
Impact Factor- 3.25
video band are synthesized. Some of the used active
elements allow controlling current gain which is very
useful in applications. A novel electronically tunable
mixed‐mode biquad filter employs only three multi‐
output current controlled current conveyor trans‐
conductanceamplifiers(MO‐CCCCTAs)andtwogrounded
capacitors. With the current as an input, the proposed
filtercanrealizelowpass(LP),bandpass(BP),highpass
(HP),bandreject(BR)andallpass(AP)incurrent‐mode
and LP, BP and BR responses in trans‐impedance mode.
Whenthevoltageactsasaninput,theproposedfiltercan
realize LP, BP, HP, BR and AP responses in trans‐
admittance‐modeandLP,BPandBRinvoltage‐mode.A
CMOS implementation of CCCII+, CCCII‐, DOCCCII circuit
in 65nm CMOS technology is presented. The design
achieves good linearity, low power dissipation and high
bandwidth in the device. As an application a current
mode second order universal filter is simulated (Low
Pass, High Pass, Band Pass, All Pass and Notch filters)
using two DOCCCII and two capacitors.A new first‐order
voltage‐mode filter employing minimum active and
passive components is proposed which employs one
differential voltage current conveyor (DVCC), one
grounded capacitor and one resistor. It maintains the
following advantageous: (i) employment of only one
currentconveyor,(ii)employmentofonlyonegrounded
capacitor, (iii) employment of only one resistor, (iv)
simultaneous realization of voltage‐mode first‐order low
pass,highpassandallpassfilterresponsesfromthesame
configuration, (v) no need to impose component choice
conditions and (vi) low active and passive sensitivity
performancesIt offers the advantages of independent
control of the condition of oscillation and frequency of
oscillation,availabilityoftwoexplicitquadraturecurrent
outputsandtwoquadraturevoltages,useofallgrounded
passiveelementsandlowactiveandpassivesensitivities.
A pair of current‐mode sine‐wave oscillator circuits is
implemented using positive second‐generation current
conveyors (CCII+). The principle of the first oscillator is
basedonaconventionalWien‐bridgenetwork.However,
this implementation suffers from the use of a floating
capacitor, which can be unacceptable in the case of on‐
chip integration. This drawback is solved in the second
variant via a slight modification of the Wien‐bridge
network, which then allows the use of all capacitors
grounded.Thecurrent‐modequadratureoscillatorsusing
2
current
controlled
current
differencing
transconductance amplifiers (CCCDTAs) and 2 grounded
capacitors are presented which can can provide 2
sinusoidaloutputcurrentswith90ºphasedifference.The
oscillation condition and oscillation frequency can be
electronically/independentlycontrolledbyadjustingthe
bias current of the CCCDTA. A novel oscillator circuit
using current feedback amplifiers has been presented.
The concept behind this design is negative impedance
realized using CFA. The circuit belongs to the class of
Active‐RCtypeoscillatorsusinggroundedcapacitors.One
of the CFA is used to simulate negative capacitor. It is
suitableforuseforlowandhighfrequencyapplications.A
current tunable current‐mode sinusoidal quadrature
oscillator, constructed from only three current
differencing transconductance amplifiers(CDTAs) and
two grounded capacitors with the absence resistor, is
presentedandanalyzed.Theproposedoscillatorprovides
the important advantage of non‐interactive electronic
International Journal of Science, Engineering and Technology- www.ijset.in
ISSN (O): 2348-4098
ISSN (P): 2395-4752
control of the oscillation condition and the oscillation
frequency and is capable of generating two quadrature
current outputs. The circuit exhibits low active and
passive sensitivities and is suitable for integration.It is
showninthatanycurrentmodeanalogcircuitcomprises
of a current mirror (CM) and voltage buffers (VB) and
their properties affect the operation of low voltage
circuits.Thelowvoltagecurrentmirrorsprovidethehigh
voltage swing capability at the output terminal, but they
do not have high input swing capability. They require a
margin of at least one threshold voltage (VT ≈ 0.8) for
properoperation,whichisquitelargeforasupplyvoltage
of 1.0 V. The VB must provide rail‐to‐rail output voltage
swings with low output impedance. At low voltage, the
mainconstraintsfacedarethedevicenoiselevelandVT.
Reduction in VT is dependent on the device technology.
HigherVTgivesbetternoiseimmunityandthelowerVT
reducesthenoisemargintoresultinpoorSNRandresult
in very complex circuits. So there is a need for simpler,
smarter and efficient circuits. Many new design
techniques for the low voltage analog circuits are
available viz., MOSFETs operation in (a) sub‐threshold
region, (b) bulk‐driven transistors, (c) self‐cascode
structures,(d)floatinggateapproachand(e)levelshifter
techniques. CCII uses a voltage follower to synthesize
inputs Y and X and two complementary current mirrors
thatallowrecopyingthecurrentonportXtoportZ.Itis
presented in that if the voltage follower is implemented
usinganop‐amp,ithasallthedrawbacksthatresultfrom
the use of an op‐amp: reduced ‐3 dB bandwidth, more
important power consumption, and also large silicon
area. When the voltage follower is implemented with a
mixed translinear loop using complementary bipolar
transistor,theCCIIischaracterizedbycutofffrequencies
aroundseveralhundredofMHz.
Figure2:Oscillatorusingcurrentdifferencingbuffer
amplifier
3. METHODOLOGY
Traditionally, the analog electronic circuits are designed
using voltage mode building blocks (Op‐Amp). Recently,
the current mode building blocks have been proved
advantageousindesigninganalogintegratedcircuitsand
some ofthe circuits such as filters have been developed.
Currentmodebasedrealizationofanalogcircuitshasnot
beenexploredmuchandneedtobeexploredfurtherfor
more applications pertaining to new technological
developments. The ultimate goal of this research is to
design, implement and performance evaluation of
electroniccircuitsusingcurrentmodebuildingblocksfor
VLSI application. The research focus is to improve the
performanceoftheelectroniccircuits.
Following are the objectives of the proposed research
work:

Designing of integrated circuit basic building blocks
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MONIKA CHOUDHARY et al.
Volume 3 Issue 3: 2015
Citation: 10.2348/ijset06150825
Impact Factor- 3.25
such as filters, rectifiers, oscillators using current
mode building blocks for very large scale integrated
circuitapplication.

ISSN (O): 2348-4098
ISSN (P): 2395-4752
Systems and Mobile Communications and Learning
Technologies,Apr.2006,vol.150,no.150,pp.23‐29.
2.H. H. Kuntman and A. Uygur., "New possibilities and
trends in circuit design for analog signal processing,"
International Conference on Applied Electronics, Sept.
2012,vol.1,no.9,pp.5‐7.
Implementationandperformanceevaluationofthese
integratedcircuitsthroughsimulationtechnique.
4. RESULTS
3.NikhitaTripathi, Nikhil Saxena and Sonal Soni, “Design
of an amplifier through second generation current
conveyor,” International Journal of Engineering Trends
andTechnology,vol.4,issue5,May2013.
4.K. C. Smith and A. S. Sedra, “The Current Conveyor‐ A
NewBuildingBlock,”Proc.oftheIEEE,Aug.1968,vol.56,
no.8,pp.1368‐1369.
5.A. Sedra, K. Smith, “A second‐generation current‐
conveyor and its applications,” IEEE Trans. on Circuit
Theory,vol.17,no.1,pp.132‐134,Feb.1970.
Figure3:Spicesimulationresults
6.Amruta Bhatt, “Design and analysis of CMOS current
conveyor,” Journal of Information, Knowledge and
ResearchinECE,vol.2,issue2,Oct.2013.
7.Indu Prabha Singh, Kalayan Singh and S.N. Shukla,
“Current conveyor: novel universal active block,”
Samriddhi‐Journal of Physical Sciences, Engineering
Technology,vol.1,issue1,2010.
8.KamleshKumarSingh,GeetikaSrivastava,RaviShankar
Mishra,DeepakTiwari,“Currentconveyor:Anovelactive
building block prevailing op‐amp limitations,”
International Journal of Innovative Technology and
ExploringEngineering,vol.2,issue2,Jan.2013.
Figure4:Spicesimulationresults
5. CONCLUSION
EarlierOp‐Ampswereusedforanalogcircuitdesign.But
due to their limited performance such as bandwidth,
slew‐rateetc.ledtheanalogdesignertosearchforother
possibilities and other building blocks. As a result, new
current‐mode active building blocks such as OTA, CCII,
etc. receive considerable attention due to their larger
dynamic range and wider bandwidth. Advantages of
current mode techniques are high frequency, lower
power consumption, high slew rate, better linearity,
better accuracy and higher bandwidth. Using these new
activeelementsforanalogdesignandimplementingthem
in CMOS and beyond CMOS technologies, Op‐Amp based
problems can be solved. The study of current mode
circuitsforvariousapplicationshasnotbeendoneupto
great extent. So many integrated circuits are required to
be designed using current mode circuits. The proposed
research work aims at design and performance
evaluation of various VLSI circuits using current mode
techniques.
REFERENCES
1.LattenbergandVrba,"Filterswithcurrentamplifiersfor
high‐speedcommunication,"InternationalConferenceon
International Journal of Science, Engineering and Technology- www.ijset.in
9.Nejib Hassen, Thouraya Ettaghzouti, Kamel Besbes,
“High‐performancesecond‐generationcontrolledcurrent
conveyor CCCII and high frequency applications,” World
Academy of Science, Engineering and Technology 60,
2011.
10.Varun S. Kshatri, John M. C. Covington III, Joshua W.
Shehan, Thomas P. Weldon, and Ryan S. Adams,
“Comparisonof CMOScurrent conveyorcircuits for non‐
fosterapplications,”Proc.oftheIEEE,2013.
11.SusheelSharmaandRockeyGupta,“Voltagecontrolled
current conveyor and its application,” Proc. of the Intl.
Conf. on Advances in Computer Science and Electronics
Engineering,2012,pp.389‐393.
12.P. Kumar, K. Pal and G. K. Gupta, “High input
impedenceall‐passandnotchfilterconfiguration,”Indian
Journal of Pure & Applied Physics, vol. 44, pp. 398‐401,
May2006.
13.S.Maheshwari,S.V.Singh,D.S.Chauhan,“Electronically
tunablelow‐voltagemixed‐modeuniversalbiquadfilter,”
IETCircuits,Devices&Systems(J),vol.5,issue3,pp.149‐
158,2011.
14.Fırat Kaçar and Serdar Menekay, “Realization of a
CMOS current differencing buffer amplifier and its filter
application,” International Conference on Electrical and
ElectronicsEngineering,1‐4Dec.2011.
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