A New Approach to Design & Implication of Colpitts Oscillator Using CCCII

Transcription

1 olume 5, ssue 6, June 6 A New Appoach to Design & mplication o olpitts Oscillato Usg Ankit Tyagi, M Saga Abstact n this pape, an ducto-less tunable olpitts oscillato is designed usg second geneation cuent contolled cuent conveyo () as active block. The cicuit contas thee AD844/AD s and thee capacitos. The ducto has been eplaced by an active mode ducto connected to gound designed usg second geneation cuent contolled cuent conveyo. The ma advantage o poposed olpitts oscillato cicuit is that it is ee om esisto and ducto. The oscillation equency has been made tunable electonically by adjustg the capacito value and though the bias cuent. The simulation has veiied usg ORAD v.5 and expeiment has also been peomed with AD844/AD. cost. Hence, it attacts the attention to abicate a lage numbe o analog as well as digital cicuits on a sgle silicon wae (chip). So, the digital designe also comotable with the analog cicuit design because digital, ew sub designs ae ist conveted s-doma then conveted to z-doma. The Figue shows a ough low steps o the analog cicuit design which undamental laws o cicuit and the design concept o tansistos, thei popety and the essential design paametes as well as semiconducto technology plays impotant ole o the impovement o the analog design. ndex Tems, olpitts oscillato, Op- Amp, ORAD v.5. NTRODUTON n paticula, the voltage opeational ampliie apidly become the ma analogue block and domated the maket sce the vention o the ist analogue tegated cicuit. Nowadays, the situations ae changg because thee is a new impulse towads these called cuent mode cicuits, which ae able to ovecome the limitations o a constant gabandwidth poduct and elationship between speed and bandwidth, so that peomance can be impoved tems o low-voltage chaacteistics and o slew-ate and bandwidth. The concept o tegated cicuit ist gave by a physicist namely G. W. A. Dumme 95 and late discoveed by Jack Kilby 959 which he cocided with the development o planne technology. Eveythg nea to us that we see, hea and sense physical lie is analog like ou voice, music, audio and physical activity etc. Analog design becomes moe amilia and popula daily lie like ou laptop, cellula phones, heag aid, nanotechnology pobes, unmanned aeial vehicles, obots, electonic gadgets etc. The impovement o tegated cicuits (s) contag mixed analog and digital unctions on a sgle silicon chip give a new appoach o the analog designe. Recent advances analogue s design becomes technology speciic due to the eective use o MOSFETs, BJTs, Bipola and complementay metal oxide semiconducto ield eect tansisto devices (BiMOS) and high speed Gallium Asenide (GaAs) devices []. Also, ey Lage Scale ntegation technology, analog cicuit plays an eective ole o the demand o the analog and digital pocessg s which povides a bette eliability and to educe hadwae Ankit Tyagi, EE Depatment, SG Samalkha, Panipat Figue Schematic diagam o Analog cicuit design [7] Active olpitts oscillato designed cuent contolled cuent conveyo () technology has been new idea o LS technology. n this pape an ducto-less tunable olpitts oscillato designed usg second geneation cuent contolled cuent conveyo as an active block. The cicuit has thee s and thee capacitos. The ducto has been eplaced by an active mode ducto which is connected to gound and designed usg. The ma advantage o poposed olpitts oscillato is ee om esistance and an ducto that causes suitable o monolithic tegated cicuit design. The oscillation equency has been made tunable electonically by adjustg the capacito value and though the bias cuent. The simulation has veiied usg ORAD v.5.. DESRPTON OF URRENT BULDNG BLOKS AND OLPTTS OSLLATOR A. Second Geneation uent onveyo n 968, Seda and Smith toduced a thee temal analog device called the ist geneation cuent conveyo (). The thee temals o labelled as x, y and z ae chaacteized by the equations matix om witten as: M Saga, EEE Depatment, APT SD ndia, Panipat All Rights Reseved 6 JAREE 7

2 olume 5, ssue 6, June6 y X Z X Y Y () Hee, the plus and mus signs epesent positive and negative. The emegence o second geneation cuent conveyo () is just the modiication o the ist geneation cuent conveyo. The cicuit symbol o is shown Figue. t ceases the vesatility compaison to because the Y temal exhibits ite put impedance i.e. Y = and othe two temals chaacteistics ema the same, the equations is matix om witten as: y X Y Z Y () Figue icuit symbol o [] The can be used o vaious applications like contolled souces, impedance convetes, impedance vetes, and gyato and as vaious analog opeational elements (Seda et al. 97) [9]. B. Pactical iew o The equency peomance o pactical dies om the ideal one because o non-idealities. Figue. shows the pactical equivalent cicuit o with its paasitic components o a ixed value o bias cuent. This is simila to pactical but it dies at temal X whee an ductance Lx is connected seies with the vaiable esistance to take an account o the vaiation o the impedance at temal X as a unction o equency.. Figue 4. BJT based tenal stuctue o DO []. MPLEMENTATON OF OLPTTS OSLLATOR A. Second Geneation uent ontolled uent onveyo Second geneation cuent contolled cuent conveyo () can povide electonic contol vaious cicuits like ilte susoidal oscillato etc. The cicuit symbol o the and its tans-lea cicuit is as shown Figue 5. Futhe use X and Y to denote cuents and X and Y to denote the voltages at temal X and Y espectively. R x T denotes tsic seies put esistance o a o tans-lea mixed loop (Q to Q4) at the X pot which can be electonically tuned via and T =6 m, the themal voltage at oom tempeatue. Hence, the electonically contolled tsic esistance, R x at temal X can be changed by the bias cuent o cuent contolled cuent conveyo (). B. nducto Based On uent onveyo Hee, an ducto based on two cuent conveyos, one with positive tanse and the othe with negative tanse and capacito used. The implementation o this ductance is illustated Figue 5 Takg to account the pesence o paasitic esistos R x and R x : R x x x () R y x j x x Accodg to equation (4), we have: (4) Figue Pactical with its paasitic components [9] A dual output cuent contolled cuent conveyo (DO±) [] havg both positive and negative cuent tanses may be obtaed by addg coss coupled cuent mio ode to evese the cuent diection though the Z- temal as shown Figue 4. jr (5) x x These two equations (4) and (5) give: R R j (6) x x x The put impedance is given by the ollowg equation: Z R R j (7) x x All Rights Reseved 6 JAREE 74

3 olume 5, ssue 6, June 6 t is equivalent to an ductance L o: the tunable active ductance value. R X = R X = R X (R X L eq R R j (8) x x T o ), esonant tunable equency R x eq given as: Also witten as: () T eq Figue 5 The ealization o an active ducto connected to gound [6]. nducto-less olpitts Oscillato icuit and Tunable Fequency nducto-less active mode olpitts oscillato, well designed usg two gounded capacitos and tunable active mode ducto with analog buildg block as the active device. The based active mode ampliies X temal has connected to the junction o capacitos, seies connection o and (cente o the two gounded capacitos) which placed acoss a common ducto L act as a simple voltage divide. The amount o eedback depends on the values o and. The equied extenal phase shit has obtaed with the positive eedback obtaed o sustaed un-damped oscillations. The chaacteistic equation o active mode ducto less olpitts oscillato witten as: s s RX R x R x Rx Rx (9) Hee, above equations poved that the equency o oscillations o active mode ducto-less olpitts oscillato have diectly contolled by bias cuent and gounded capacitos, which povides a suitable advantage o monolithic tegated cicuit () implementation. The equency o oscillation can be adjusted dependently by whee equency o oscillation has vaied without changg the passive component and electonically usg capacito thus the cicuit can wok as a cuent contolled oscillato.. RESULTS AND DSUSSON n ist step, we eplace the op amp with active block o second geneation cuent conveyo (). Also o pactical implementation o the cicuit, AD844/AD is used. n next step, we eplace active block o second geneation cuent conveyo () with the active block o second geneation cuent contolled cuent conveyo (). Similaly, AD844/AD and passive components such as ducto and capacitos ae used o pactical implementation. n poposed wok, we eplace the ducto with the active block o ducto which is designed by usg. We also use thee AD844/AD s and capacitos o the pactical analysis. The simulation showed o two dieent values pf and pf. Above obtaed esults veiied the theoy that o the constant value o passive component (capacito), also equency has been ceased with the values o bias cuent. eq is the equivalent capacito o and connected seies given as: eq O eq () The equency o oscillations o active mode ducto-less olpitts oscillato has detemed by the esonant tunable equency given as: R R x x eq () Whee, R x, R x epesent the tsic seies put esistance o the cuent conveyo at the X temal o which is electonically tunable via and R x R x gives Figue 6 olpitts oscillato tank cicuit and poposed nducto-less olpitts oscillato usg All Rights Reseved 6 JAREE 75

4 olume 5, ssue 6, June6 A. olpitts Oscillato Usg Op- Amp and its Simulation Results. Figue 7 olpitts oscillato usg op amp (L=uH, ==nf) Figue 9 Tiple AD844/AD and components value = = =p Figue Simulation Result Figue 8 Simulation Result n Figue 7 & 8, olpitts oscillato with op amp cicuit and its esponse is given. The vaious omponent s values ae given as R=K, R= K, L=uH, ==nf & Feq. = 5M. Now we eplace the op amp with active block o / and AD844/AD. Also we obta the espected esults as shown the igue 9 with the vaious components values n igue 9 &, thee AD844/AD s ae eplaced by the complete olpitts oscillato cicuit usg op amp. Hee, an active block o ducto which is designed by usg two AD844/AD s is used as shown. n this design, thee capacitos, & with p values ae used. The simulation esult shows the waveom vaiation with espect to time. n igue, capacito values ae vaied espectively as =p =p & =6p. Also two esistos may be used as R= & R= to obta moe impoved simulation esult. All Rights Reseved 6 JAREE 76

5 olume 5, ssue 6, June 6 REFERENES Figue Sgle AD844/AD and components value = =n, L=uH []. Toumazou, F.J Lidgey and D.G Haigh, Analogue design: the cuent- mode appoach, EE icuits and systems seies, pete peeges Ltd.,99 [] B. Wilson, Recent developments cuent conveyos and cuent mode cicuits, EE poc. G. vol.7, pp. 6-77,99 [] G. Fei and N.. Guei, Low-voltage Low-powe MOS cuent conveyos, Kluwe Academic Publishes, [4] A. F. Abel, J. E. Bowes and J. Lauch, Low-noise high speed optical ecive o ibe optic systems, EEE J. Solid-State icuits. vol.9, pp.55-57,984 [5] T. Kaulbeg, A MOS cuent-mode opeational ampliie, EEE J. Solid-State icuits, vol. 8, pp ,99 [6] M. Kennedy, Robust OP Amp ealization o hua's cicuit, Fequenz, vol. 46, no., pp. 66-8, 99 [7] P. E. Allen and M. B. Tey, The Use o cuent Ampliies o High Peomance oltage Applications, EEE J. Solid-State icuits, vol.s5, pp. 55-6,98 [8] K.. Smith and A. Seda, The cuent conveyo: A new cicuit buildg block, EEE Poc. icuits and Systems, vol.56, pp.68-69,968 [9] A. Seda and K.. smith, A second geneation cuent conveyo and its applications, EEE Tans. icuit Theoy. vol. T-7, pp.-4,97 [] A. Fabe, Thid-geneation cuent conveyo: A new helpul active elements, Electonics Lettes. ol., pp.8-9,995 [] A. Soliman, New cuent mode iltes usg cuent conveyos, nt. J. Electonics (A.E.U). vol. 5, pp.75-78, 997 [] A. Fabe, O. Saaid, F. Wiest and. Boucheon, High equency applications based on a new cuent-contolled conveyo, EEE Tans. ic. Syst.. vol.4, pp.8-9,996 [] H. O. Elwan and A. M. Soliman, Novel MOS dieential voltage cuent conveyo and its applications, EE poc.-icuits Devices Systems, vol.44, pp. 95-,997 [4] W. hiu, S.. L, H. W. Tsao and J.J. hen, MOS dieential dieence cuent conveyo and thei applications, EE poc.-icuits Devices Systems. ol.4, pp.9-96,996 [5]. A. Awad and A. M. Soliman, nvetg second geneation cuent conveyos: the missg buildg blocks, MOS ealization and applications, nt. J. Electonics. ol.86, pp.4-4,999 [6] Ashish Ranjan, Moua Ghosh, Sajal K. Paul: MOS Susoidal oscillato usg uent conveyo,poc. O nt. olloquiums on compute electonics electical mechanical civil Figue Simulation esult Autho s Poile. ONLUSON The poposed stuctues ae designed with the help o ORAD v.5 simulato which poduces vey accuate esults. n this wok the chaacteistics o active mode ducto less olpitts oscillato is obtaed by solvg the equation which is obtaed by applyg Kichho s voltage law and cuent law. Active mode nducto less olpitts oscillato is designed usg cuent contolled cuent conveyo () which povides electonic contolled via bias cuent. Active mode ducto-less olpitts oscillato cicuit usg was poposed with apat om oeg almost all the advantage like less numbe o hadwae only capacito ae used no ducto and esisto is used o simulation which is best o abication. The design has been simulated usg cicuit simulato ORAD v.5 which the active block made o a BJT based stuctue o cuent contolled cuent conveyo usg the mode paamete NRN and PRN. Also pactical ealization o expeiment is done usg commecially available analog AD844/AD and standad value components.. M. Ankit Tyagi is an Assistant Poesso at Samalkha Goup o nstitutions, Samalkha. He completed his MTech Degee om Kuuksheta Univesity Kuuksheta. His eseach aea is Electonics & ommunication Engg. M. Saga is wokg as an Assistant Poesso Electical & Electonics Engg Depatment at APT SD ndia, Panipat. He has Published many eseach papes and his eseach aea is Electical & Electonics Engg All Rights Reseved 6 JAREE 77