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MOCI R WAVE DDISO E
TRSNA F RE ECLE T NOR DEV CI ES
I TN OR DU TC ION: hT e application of owt -t er nim al se imconduc t ro d ve ices at im crowa ev fre uq e cn ies sah b nee ni cer a des su gae gnirud t eh pa ts de sedac . ehT CW, va er a eg , a dn kaep rewop o tuptu s of ht se e ecived s ta h gi her mic evawor f icneuqer es are m cu h gral er t ah n t oh se ob tai n abl e with ht e b se t pow er trasn ist ro . The ocmm no c rahatc re isti c of a ll cativ e wt o-ter im nal osdil -stat e d ve ices is thei r en gati ev eris sat n ce. ehT era l pra t of ht eir mi pedance is neag ti ev o ev r a r na ge of frequ ne ic es. nI a op is ti ev resistan ce eht ruc r ne t ht or u hg the ser i nats ce na d eht v egatlo arc os s it are in sahp e. hT e egatlov pord orca ss a tisop ive tsisera cn e is evitisop dna a ewop r of (12 R) is di ss i ap ted in the resi stance. nI a agen evit resist na c ,e revewoh , ht e c nerru t dna egatlov a er out of esahp yb 81 0°. The vol at eg d or p ac or ss a ne ag ti ve resis at nc e is en gati ev , and a pow re of (-I!R) is gene rat de by t eh pow re su pp ly assco iate d htiw th e negta iv e rse istan ec . nI op siti ev resistances abs bro . pow re (pa ss ive device )s , wh re e as ne ag tive resistances eg n are te opw er (active dve ic es). In this hcapt er t eh transfe err d ele ctro n ed vi ec s(TED )s are analyz ed. ehT d fi f nere ces eb twe ne mi rc o evaw art n is st sro dna narts f derre ele c nort vedic es (TDE )s are fundamen lat . rTa sn i st ro s o rep eta iw th e tih er ujcn ti no s ro gat e ,s tub DET s a er b klu ed civ es vah i gn on ju noitcn s ro setag . The ma iroj ty of rotsisnart s era f cirba a det f or m elem ne tal sem i oc n cud t ro ,s hcus sa nocilis or egrm na ium, hw re eas 1tDs a er fa rb icated from co pm ou dn se im conductors, such as www.getmyuni.com M ci ro aw ves & Rada r 01 CE 45
illag um ars dine e ( A.r s) i, dn ium hp so p edih (l Pn ), or ac dmium tell ediru (Cd eT ). rTansistors op re ta e As "warm" electr ons wsoh e e en rgy si n to much g er ta er than the ht ermal energy 0.02 e6 Vat room te pm eratur e) of e el ctrons in t eh semicond cu t ro s.
UG NN EFFECT DOI D SE – GaAs diode
nnuG eff tce era named after .J B. nuG n w oh si 3691 ocsid v re ed a cidoirep f tcul u noita of tnerruc issap ng ht r hguo the n- type llag ium sra enide . w neh the ppa lied ov ltage xe ceed de a certain cr ti i ac l val eu .
lkcohS ey in 591 4 sug detseg aht t hte two t re m ani l en g ita ve res ista ecn dcive es su ni g semicond cu tro s h da ad av tn ages ov re tra sn ist ro s at high frequenci se .
nI 1691 , R ldi ey and Wa snikt des debirc a wen htem od f ro bota i gnin tagen iev dif fer ne tial mob ili ty in esim c o dn uc ot rs. ehT elpicnirp ovni l dev is ot taeh reirrac s ni a thgil ma ss , low mo ilib ty , ih g reh ene rgy s bu dnab wh ne ht ey ah ve a gih h tem ep rature.
laniF ly orK em re tats ed taht eht nigiro of t eh evitagen diffitnere a l mo ilib ty is ldiR ey taW k sni iHsl um’s m hce an si m of el nortce nart sf re otni the llav e sy aht t co cur ni con udcti on ba sdn .
Gunn effect:
ehT leb ow f erugi s oh ws eht gaid ram of a uniform n-type GaAs oid de tiw h ohmic tcatnoc s at the dne us rf ca e .s G nnu ats ted th ta “ Above so em irc ti lac gatlov e , dnopserroc i gn to na ele cirtc f lei d of 0002 to 0004 /stloV cm, ht e cu tnerr ni eve ry ceps i em n beca em a fluctu nita g fnu oitc n of time . www.getmyuni.com M ci ro aw ves & Rada r 01 CE 45
Gunn Dio ed s Sin lg e p ei ce of GaAs or Inp an d contai sn no j cnu tions
hxE ibits ne ag ti ev differ ne tial r se si ta cn e
Ap ilp c ita on :s low- on ise loca l osc alli t sro for mixers (2 to 140 HG )z . oLw -p ower transmitt ers an d wi ed b na d tunba le so ru c se
ounitnoC us- evaw (CW) wop er evel ls of pu to reves al uh n derd mill sttaw ac n be deniatbo in eht X-, uK -, dna Ka-ba .sdn A wop er o tuptu of 30 mW nac be hca ieved from co mm ercially a av ilable devi ces at 94 HG z.
rehgiH po rew nac be veihca ed by combin gni reves al ived ces ni a rewop combi ner. www.getmyuni.com M ci ro aw ves & Rada r 01 CE 45
G nnu so ic lla ot r s ex ih bit very low dc-t o-RF ef if ciency of 1 ot 4%.
G nnu a sl o di cs overed tah t the thresoh l d ele tc ric field Eili av ir ed wit h t eh lengt h na d type of mate ir al. He de ev l po ed an le aborat e ca ap ci it ve rpo eb for plotti gn the ele tc r ci fiel d id s irt bu iton tiw h ni a ps ecimen of n-t py e GaAs of leng ht L = 21 0 JLI ll dna orcss -se c t lanoi area 5.3 x 10-3 cm2 with a wol -fi dle siser tan ec of 16 .n ruC r ne t isn t ba il iti se oc ruc r de ta specimen volt ga es abo ve 59 ,V whi hc means hta t t eh ht er shold fie dl is
RIDL YE WATSKIN DNA HILSUM THE:YRO
aM ny e alpxn ta ion s ha ev neeb fof re ed f ro the nnuG effe .tc nI 91 64 orK em re [6] gus g se t de t ah t Gu nn ' s sbo erva oit ns ew er in complet e ga r ee em nt iwth the Ridley- aW tki sn -Hilsum R(HW ) t oeh ry.
iD ffe er nt ai l N tage i ev R se i ts ance:
ehT fundam ne t la conc tpe of eht ldiR ey-Wat snik - sliH um (RW )H t oeh ry is eht fid fe laitner vitagen e res natsi ce ved el depo in a klub dilos - etats III -V com nuop d nehw rehtie a gatlov e o(r cirtcele f )dlei ro a c tnerru si ap deilp ot the et rm ani ls of eht sampl .e ehTre a er owt m edo s of n evitage - iser stcna e ved ices: egatlov - cno rt o ell d a dn c ru rent noc t or lled M do es.
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nI ht e vo ltage-c on rtol led m do e t eh uc rre tn density can be mu lit v ula ed, w eh reas in eht tnerruc - noc t dellor mode eht tlov a eg nac eb mu ulavit1 e .d hT e maj ro eff tce of eht araeppa n ec of a diffe laitner eng evita - ser ist a ecn noiger ni ht e cur r tne isned ty f dlei vruc e si ot dner er eht sam elp le e tc r laci ly snu ta .elb As a user lt, ht e laitini ly hom enego ous sam elp ceb om se el irtce c la ly h eter oenego us ni na ta temp t ot hcaer st ba i il ty. nI the atlov ge- llortnoc ed n evitage -ratsise nce mo ed hgih -f dlei dom ia ns era formed, apes r nita g owt low-f dlei oiger ns. ehT i retn faces rapes a gnit ol w na d high -fiel d domai ns eil along e uq i po et n it als ; t suh they are i n alp nes perp ne id c lu ar to the c ru rent d ri ceit o n.
xE p er s des mathema it c laly, t eh neag ti ev resistance of ht e sample at a rapti uc lar www.getmyuni.com M ci ro aw ves & Rada r 01 CE 45
geri no si
If na el ce tr ci fie dl Eo ( ro vtlo age Vo) is ap ilp ed ot the sa lpm e, for ex ample, the ruc r ne t d ne is ty 10is gene ar ted. sA eht a eilpp d f dlei ro( )egatlov is in desaerc to E1 ro( V2), the c ru r ne t dens i ty i s d ce rea es d to 21 . Wh ne t eh f dlei o(r voltega ) si decr~ ot .£ ro( VI), eht ruc r tne isned ty is ercni ased ot ,1 . Th ese ph enomena of eht ov lt ga e con rt o lled neg ait ev resis ta ecn era show n in Fig. 7-2-3(a). Si iml raly, for teh c rru ent oc tn r ello d om de, the n ge ta ive-resi stan ec p or f eli si as shown bel o w.
T OW VALLEY MODEL THEO YR : orK em re pr esopo d a n evitage ma ss m ci rowa ev am ilp f rei in 1 859 [ Ol ] dna 1 59 9 [ ]II . gnidroccA ot eht rene gy ab nd oeht ry of ht e n -ty ep GaA ,s a hgih -m bo i il ty rewol llav ey is es para det by na en re gy of 63.0 Ve from a wol -m ilibo ty pu p re av ll ye www.getmyuni.com M ci ro aw ves & Rada r 01 CE 45
Ele tc ron ednsi eit s in the lo ew r na d pu per va ll eys remain the same nu der an uqEi bil ri um con oitid n. W neh eht deilppa le e cirtc f dlei si rewol ht an ht e irtcele c fiel d of t eh low re valley (E < Ee) , no e el ctron s liw l transf re to the up rep valley.
Wh ne the applied le ectric field is hi hg er than tah t of the lo ew r av lley na d lower t nah t ah t of ht e upper va ll ey ( eE < E < Eu )) , el ce rt sno iw ll eb nig to t ar nsf re to ht e upper va ll ey.
nehw eht ilppa ed tcele ric field si rehgih naht t tah of eht reppu va ll ey ( uE < E,) a ll ele tc ro sn will rt na sfer to the up ep r valley.
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Wh ne a suff tneici ly hgih fi dle E si deilppa ot eht s cep im ne , snortcele era a eccl re at ed dna rieht fe f itce ve tem ep r ruta e sesir voba e ht e ittal ce et m ep ratru e al os i rcn ea ses. Thu s electron ednsi ty/I an d a er obth fu cn tions of elec t ri c field E.
MODES FO OPERATNOI OF UG NN DI EDO :
A ugnn di doe c na ope rat e ni four mod se :
1. G nnu socillation m do e 2. st ba el am p lif ci ation mo ed 3. SL A oscil lati no om ed 4. Bi sa icrcui t csoi ll ati no mode
Gunn osci all ti on mode: sihT mo ed is def ni ed ni eht ger ion rehw e t eh tcudorp of f uqer ency m pitlu l dei by tgnel h si a tuob 107 cm/s a dn ht e rp o ud tc of gnipod muitlp il e d by l ne tg h is erg ta er th an 1012/cm2 . nI ht is rge i no t eh devi ec si u sn table uaceb se of eht c cilcy form noita of ehtie r eht ca cumul ita on lay re ro eht hgih f dlei domain. www.getmyuni.com M ci ro aw ves & Rada r 01 EC 45
When ht e cived e is op detare si a italer vely hi hg Q ac vity and puoc l de pr epo rly to t eh l ao ,d the dom a in I uqe cn h de or delayed befo er n cu l ae ti gn .
.2 St ba le amp il ficta i on m do e: hT is mode si def ni de i n ht e reg oi n whe er ht e p or d cu t of fre uq e n cy times l gne th is a ob ut 107 lmc s dna t eh pr oduct of dopi gn mit se el gn th i s b e tween0 l 11 dna 1O12 2mc/ .3. LSA ocs alli ti no mo ed : hT i s m do e is defined in th e rge io n where the product of fqeru ne cy tim se l e ngth i s abo ev 1 07 clm s a dn t eh uqto ei n t of d po i gn div di de by fqeru ne cy is ebewt e n 2 x 01 4 nad 2 x 105. 4. saiB -ci tiucr o llics a noit mode: hT is mode srucco only weh n t ereh si ie th re nnuG or LSA os llic at .noi nad it is lausu ly ta ht e iger on rehw e the orp duct of fqeru ne cy time s le ng ht is too sm a ll ot appe ra in th e fi ug re. ehWn a bul k doi ed i s bias de ot th er s oh ld. th e va e ar ge c ru rent suddenly d or ps as uG nn o cs illation bge i sn . www.getmyuni.com M ci ro aw ves & Rada r 01 CE 45
ehT pord ni rruc e tn ta eht dlohserht ac n dael ot cso noitalli s ni eht bi sa tiucric aht t era tpy i ac lly 1 kH z to 1 00 HM z .
leD ya ed do niam m do e 601( c/m s < Lf < 1 70 cm/ )s . ehWn ht e rt ansit t mi e i s hCo nes so th ta ht e domai n is collect de while E < Et h sa shown in iF g. 7-3-4 b( ,) a www.getmyuni.com M ci ro aw ves & Rada r 01 CE 45
wen domain nac n to form litnu t eh f dlei sir es evoba rht e dlohs iaga n. nI siht ac se, t eh osc li lati no epir od is rg eater ht na the rt an ist time- ht at is, oT > T,. This ed layed mo ed i s also c ella d nih ib eti d m do e. hT e e ffic ei ncy of th si m do e is ab out 20%. Quenched domain om de (fL > 2 X 107 c s/m ). If eht ib as fi dle spord woleb eht sus t inia ng fi dle sE rud ing ht e n ge ati ev ah lf-cycle sa ohs wn ht, e doma ni c spallo es bef ero ti r ae sehc ht e onad .e When eht saib f dlei gniws s kcab ab evo ht r dlohse ,a en w domain si lcun e deta na d eht pr eco ss per e sta . hTe er fo er ht e csoi ll ati o sn occ ru at ht e freque ncy of t eh res no ant ci cr tiu r ta her htna ta eht art n tis-time fer q neu c ,y tI sah been fou dn taht the re os n tna fr neuqe cy of ht e tiucric si lareves times eht tr tisna -time fr uqe enc ,y is n ec eno elopid seod ton vah e ne o gu h time ot read uj st na d abs bro the vo atl ge of ht e other di op l se . hT e ro ite c la ly, t eh e ffic ei ncy of quenc deh domain o cs illato sr nac r ae ch 13%
SL A MOED Wh ne the fer que ncy si ev ry hi hg , the domains od nto ah ve su ff ic ei nt t mi e ot form Whli e ht e f lei d i s above thr se ho dl . As a res tlu , m so t of ht e do am ins are ma tni ained nI ht e en gative cno d cu t na ce state du ir ng a large frac oit n of th e vo atl ge cycle. A yn A cc umulat ion of e el ctrno s near ht e ca ht do e has tim e t o collap es while ht e si ng la is eB low ht res oh ld. Thus t eh LSA mode is .t eh simpl se t mode of ope ar ti no .
VA ALANCHE TRANTIS TIEM DEVICES:
RE DA DIODE: eR ad di edo aw s ht e f ri st p or p so ed va la anche diode. T eh b sa ic oep ra ti gn pr ni ciples of IMP TA T id o ed acn eb e sa ily und sre tood by fi sr t un ed rs at nding the op are t oi n of aer d d oi ed . ehT sabi c daer oidd e sisnoc ts of f ruo layers namely n+ p I p+ layers. hT e pl su pus e sr cript refer s to ve ry hi hg dopi gn levels a dn ‘ ’i d ne to es tni r ni s ci layer A. al gr e
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esrever saib is eilppa d ac ssor edoid . the av ehcnala m lpitlu i oitac n srucco ni eht thin p“ ” reg io n hw i hc is a sl o ca ell d t eh ih gh field reg oi n or ava al nche reg oi n.
hT e h elo s eg n re ta ed duri gn the aavlan hc e proc se s rd ift throu g h ht e nitri sn ic region wh li e om vin g towa dr s p+ nocta ct. T eh oiger n wteb e ne +n p itcnuj on a dn eht i-p+ j nu oitc n is kon wn as spa ec c ah r eg regi on. Wh ne th si id ode si r ve esre bi ase d and placed i sn di e na ind cu tiv e im c or w va e cavity mic evawor oics loital ns a er decudorp eud ot eht re nos a tn noitca of the ac p vitica e mi dep a cn e of t eh di do e dna cavity ni ducta cn e. hT e dc bias pow re is c vnoe tr ed into im crow eva power by tah t read diode csoil l ta or. www.getmyuni.com M ci ro aw ves & Rada r 01 CE 45
vA a ehcnal lpitlum i tac i no co c sru nehw the ap deilp rever se saib lov t ega si aerg t re neht eht dkaerb o nw v gatlo e so taht ht e spa ec ahcrge noiger xe te dns from +n p j nu oitc n through the p na d I regi o ns, t o the i to p+ j nu cti no .
APMI TT OID DE: lm ttap doid es era am nuferutca d gnivah id ffer tne for sm su hc as n+ ,+pip nin+p +, +nn+p rba u tp uj n oitc n dna +p i n+ ddoi e c nof ugi r .noita hT e mater lai esu d fro ma un fa erutc of ht e es modes era ei reht eG rma in um, S cili o ,n G la lium rA s ne ide (GaA )s or In id um Phoshp di e (In P). tuO of ht ese m laireta s, sehgih t effci i ne cy, hi rehg po e gnitar f euqer ncy na d wol er esion si iatbo n de iw th .sAaG tuB eht id s egatnavda htiw aG As si com lp ex f ba r noitaci ecorp ss and nehce ih g reh cots . ehT f erugi woleb sho sw a esrever desaib +n ip +p doid e htiw cirtcele f dlei va ,noitair gnipod co cn ent noitar evrsus dis at nce pl ot, the im crow eva voltage swin g and the c rru ent variation.
IRPIN C PLE OF O EP RA ITNO : When a ever r es ib as v egatlo eecxe d gni ht e b era nwodk v egatlo is a ,deilpp a hi hg e cirtcel f dlei ppa e sra a sorc s eht +n p tcnuj io .n sihT ih gh f dlei tni e isn ty imparts fusf tneici rene gy ot the ecnelav el ortce ns to esiar ht e esm lves otni the udnoc c it on nab d. sihT luser ts va a hcnal e m pitlu l oitaci n of eloh - ortcele n iap rs. W hti us ibat le podi gn profile d se i ng , it i s po ssib el to mak e el cetric fie dl ot have a very sh ra p peak in t eh cl so e vic ini ty of t eh uj cn tion re us l nit g in " pmi ca t a av lanche mu cilpitl a it o "n . hTsi si a cumu lita v e ssecorp re itlus ng ni ra dip esaercni of rac rei r isned ty. oT erp v ne t the diode from ub rn ni g, a c sno t na t bias s uo rce is u es d to maintai n av re age tnerruc ta safe lim ti ,01 ehT id ode rruc net si irtnoc betu d by the dnocu c it on snortcele ihw ch move ot eht +n noiger and eht ssa o detaic oh les hcihw irdft trh o hgu eht aets dy f eild an d .c.a f .dlei · ehT doid e niw~ gs tni o and uo t of lava acn he noitidnoc s dnu er ht e inf ecneul of taht ever rse saib ets ady f lei d an d eht a.c. field. www.getmyuni.com M ci ro aw ves & Rada r 01 CE 45
uD e ot eht ird ft it me fo oh el s eb i gn ' sma ,ll ac rrie rs rd ift ot the ne d oc ntact s before eht .c.a tlov a eg iws ngs eht edoid tuo of the cnalava he D eu to b gnidliu pu of csoillatio ns, ht e a. c. f dlei sekat rene gy from t eh ilppa ed aib s dil the oitallicso ns ta mic vawor e f cneuqer ies era sust denia acsor s t eh edoid . euD ot ht is .c.a f ,dlei the ohle cu rr ent g or ws expnoen lait ly to a max imum and aag i n d ce a sy ex opn ne tial ly to eZor . gniruD ht is oh le drifti gn preco s ,s a oc n ts ant nortcele rruc e tn si in decud ni ht e e txe lanr riCcu ti ihw ch strats f niwol g hw en eloh tnerruc er ach es sti pe ka na d unitnoce s f ro h la f cycle oC r ers nidnop g to n evitage s niw g of eht a .c. atlov ge as nwohs ni f erugi uhT s a 081 seerged hP a es s ih ft neewteb eht ex ret n la tnerruc dna a. c. im orc wav e vo tl age orp iv des a ne ag tiv e Resis at cn e f ro s su tained ocs li la oit sn .
ehT rotanoser si usually tu den ot siht f er q neu cy os taht eht IM APTI edoid s orp iv de a Hi hg power co itn nuous w va e (CW) a dn up l des imrc owa ev s gi an ls.
A pp lications fo MI PA TT iD do es )i( esU d ni t eh f ani l opw re atsg e of os lid etats m orci wa ev tr na sm retti s f ro comm nu i caoit n purpo se. ( ii ) sU ed in the rt a snttim re of TV s sy tem. ( )iii U es d in FMTD / DM systems. (i )v sU de as a cim rowa ev s uo rce in lab ro atory f ro mea us reme tn purposes.
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RTAPA TT DOI DE: nociliS is sualu ly u es d f ro eht manuf rutca e of TAPART T oid des dna have a nocfi ug ra oit n of p+ n n+ sa ohs wn T. eh p-N j nucti no is re ev rse bia sed beyond hte erb akdown regio ,n so t ah t th e cu rr ent ed nsity is al gr er. T ih s edcr e saes the electric f dlei ni eht ps a ec ahc r eg noiger a dn ercni ases eht reirrac tisnart ti .em uD e ot siht , eht fuqer e ncy of repo a noit steg derewol to le ss ht an 01 GH .z tuB the effi neic cy eg st i rcn e saed due to low op w re di ss i ap tion. edisnI a oc-ax lai oser n ,rota eht TR PA A TT di edo si on rm la ly mo nu t de ta a niop t erehw xam imum RF v egatlo sw gni is iatbo n .de When the com nib ed cd saib dna FR tlov a eg exceeds br nwodkae egatlov , aval ehcna occu sr na d a plasma of loh se a dn snortcele are eg ne detar hcihw g ste part pe .d Wh ne eht e retx nal tiucric ruc r ne t f ol w ,s eht tlova ge ir ses dna ht e ppart ed lp asma eg ts r saele ed orp d gnicu ruc rent eslup a orc ss eht d ir ft .ecaps ehT t lato art n tis it me is the sum of the ird ft it me and eht led ay rtni o decud by t eh esaeler of t eh deppart alp sm .a uD e to siht gnol er tisnart tim ,e ht e op re a nit g f neuqer cy is limit de ot 10 zHG . Be ac use ht e uc rr tne eslup si as detaicos wi ht wol ,egatlov eht rewop itapissid on si low gnitluser in high re e ffic ei ncy. ehT dasidv na tag se of APART TT era hgih n esio f erugi na d reneg a noit of gnorts ahrm no i sc ud e ot sh ro t rudoita n of t eh uc r re tn up sl e. APART TT edoid f dni s a noitacilpp ni S- ab nd deslup art nsm sretti for deslup rra ay dar ar system s.
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ehT e el ctri c fiel d is exp ser sed sa
BTAR TI D OI DE ( Barrie r i jn e tc ion transm ti tim e dve iec s ): TTIRAB cived es era an im orp ved srev i no of TTAPMI cived es. MI PATT dev ci e s employ impac t oi nizati no t ce hni uq es wh ci h is t oo on isy. Hence ni order ot ach ei ev wol esion f serugi , impca t zinoi a noit is a dediov ni BATTIRR cived e .s hT e min iro ty iitcejn o n is dedivorp by nupc h- hguorht of eht etni rme etaid ger ino ed(lp etio n reg oi n). Th e secorp s is ba lacis ly of ewol r sion e aht n impa tc azinoi t oi n bisnopserl e f ro c rru ent itcejni on in na I PM TTA . ehT n itage ve ratsise nce is boiat ned on cac uo n t of t eh rd ift of ht e inj ce t ed oh el s to the co ll e tc or e dn of t eh p-ma et r ai l. www.getmyuni.com M ci ro aw ves & Rada r 01 CE 45
ehT co sn t ruc noit of a BA TTIR devic e c no sist i gn of eim t t re , bas ,e interme id at e ro drift or ped let de erg i no dna co ell c ot r. An e ss ential req iu rem ne t f ro eht BA R TTI d ecive is htere f ero aht t eht i etn rm aide te irdft region be e eritn ly detelped to ac u es pun hc htr hguo ot the e ttim er- esab cnuj t noi iw t tuoh ac u nis g avalan hc e breakdown of t eh abse -oc lle tc ro junc oit n.
ehT para citis suoh l d be pek t sa low sa poss bi le. The equ vi al ent circ u ti ed pen sd on t eh type of enca usp lati no a dn monu ti gn am ke. roF many applic ita ons , t eh re sh uo ld eb a egral pac a cnatic e ,noitairav sma ll va ul e of m ni imum pac ac ti a ecn dna ires es ser tsi ance Rs' pO re ta ion si normally li tim ed to f 0l/ [25 HG z for iS a dn 09 GHz f ro GaAs]. qerF u ne cy of o noitarep beyo dn (f 01/ ) sdael ot ercni a es ni R, esaerced in fefici ne cy and ni rc ea es in on i es .
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AP AR ME RT IC AMPLIFIER :S
ehT rap am cirte am lp ifier si na am ilp f rei isu ng a ecived hw o es er act ecna si va eir d to p or duce amp il fi ac tion. V cara t ro dio ed is th e most widely us de acti ev ele em nt in a rapa tem r ci a ilpm fi re . It is a low n io se amp il fi er eb c ua se no eris sta n ec is niov lved ni eht am lp ify gni orp c .sse erehT lliw eb on teh r lam ion s ,e as eht a evitc le e nem t esu d i vn lo ved is eracti ev c(ap ca i it ve ). Amplifi ac ti no is bo tained if the rea cat nc e is rav i de e el ctronic la ly ni som e prede et r im ned fa hs oi n. euD ot eht adva atn ge of low ion se amplif ci a ,noit rap a rtem ic am lp i f srei ra e evisnetxe ly used ni s tsy e sm such sa gnol ra gn e sradar , slleta ite gr dnuo ats t oi ns, oidar pocselet e ,s itra fi laic tilletas e ,s microw eva nuorg d commu in c noita itats o ,sn dar io sa t or onm y etc.
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saB ic P ra am rte ic mAilp fi re A noc v ne tio an l amplifi re su es a variabl e eriss t na ce and a d.c. opwe r s ppuly. For a rapame irt c amplifi re , a rav i ba le re ca tance and na ca op w re uspp ly are en e ded . Pu gnipm angis l at f er q neu cy fp dna a sma ll am utilp de gis n la at fre neuq cy fs era ppa lied simu atl ne uo sly to the d ve ice (varactor). T eh pump osu cr e su ppli se energy to th e s gi an l (a t t eh si g an l freq eu nc )y re us l it ng in amplif ci a oit n. This oc uc rs at the ca ti ev d ve ice whe er the cap ca i vit e reac at nce vra ei s at t eh pum p fre qu ne cy.
ehT egatlov ac rso s ht e rotcarav si ercni as de by t eh pumpi gn angis l ta ea hc gis nal ov lt ga e pe ka as ohsw n ba o ev i.e., energy is at nek from eht pum p sou ecr and added ot eht angis l ta eht si lang f qeru ency. Wi ht na tupni tiucric dna lo da etcennoc d, amp il fi ac tion re us l ts. enO trop n no- edeng e etar am lp if rei si ht e mo ts comm no ly us de para rtem ic amp il f ei r. On ly thre e rf qe u ne ic se era involved - the pump, the sig nal and the idl re www.getmyuni.com M ci ro aw ves & Rada r 01 CE 45
fqer u ne ic es. If pump f neuqer cy is fp' ht e angis l f euqer ncy is fs' hten ldi er fqeru ne cy is fj = fp - fs' If fi = fs' t neh it is acll ed Deg ne e ar te amplif ei r and if fi i s on t eq au l ot fs' t neh ti is non-degen re ate amp il fi re .
sL Cs ~ ut den c ri uc ti at sgi n al ferq u ency fs jL jC ~ utn de cric u ti ta reldi f neuqer cy fj (pu pm f neuqer cy tnu ed tiucric is on t ohswn ,) ehT uot tup can be ta k ne ta i reld f neuqer cy fr iaG n si pos lbis e iw th iht s type of amp il f ei r. B ce a su e th e pum p s uo rce gi sev om re energy
nI non- eneged r eta type, lausu ly fj > fs er s gnitlu ni .niag ehT dil re cir tiuc ep rm ti s rene gy ot eb atk en from the pump so .ecru T sih rene gy si co trevn ed otni angis l f uqer ency dna i reld fr neuqe cy e ren gy dna ampl i f dei ptuo ut can be niatbo ed at e hti re frequency.
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MANLEY – ROWE RTELA ION :S
oF r ht e determi an t ion of mxa imum gai n of t eh parametric a ilpm fi re , a est of op w re noc ser av it on relations onk wn as "M na ley-Row "e er lations are quite su eful.
owt nis u ladios langis s fp na d fs a deilpp a orc ss a ol ssless time varyi gn non-li raen c pa ac ati cn e jC (t). tA t eh o tu up t of this varyi gn ca ap citan ec , ah rmoni sc of t eh wto f qer u ne ic es fp and fs ar e ge en ra et d. esehT ah rm no ci s are etarapes d us i gn band-pas s f tlier s nivah g ev ry anr or w ab nd iw dth. ehT rewop at ht e es harm cino frequ icne es is apissid t de in eht er spe evitc ser i ts iev l dao s.
rFom ht e law of co sn eravti no of een rgy, we ha ev
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ehT voba e italer on s are dellac " lnaM ey-Ro "ew pow re oc ns tavre i no tauqe ions. Wh ne hT e ewop r si su deilpp by the t ow neg e ,srotar ht en Pmn si po .evitis nI ht si c ,esa rewop wi ll f wol otni eht non-l aeni r ac p ecnatica . If ti si the ot reh way, eht n Pm n i s negati ve.
sA an xe a pm l ,e let su disnoc re eht ca es w eh n eht p rewo uptuo t fol w si la l ewo d at t eh sum frequ ne cy fp + fs no ly , w hti all the rem ainni g ah r om n ci s eb i gn po e n ci ucr i et d. W hti eht ab evo ser t itcur on ,s the eititnauq s ‘'m na d ‘n' nac at ke no av ul se -1,0 na d respect ively.
ehT op srew P0 dna1 01P era c isno der de p ,evitiso rehw eas 11P si isnoc de er d en ga vit e. :. hT e wop re niag def deni as ht e rewop uptuo t f mor t eh non-li en ra roticapac ed l derevi to eht daol ta sum fre euq ncy to taht p rewo er cei dev by ti ta a fqeru ne cy fs i s ig ven by
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suhT eht po rew iag n si eht ra oit of ptuo ut ot pni ut f neuqer cy. sihT type of rap am cirte d ecive is dellac S" um-f qer uency rap am cirte am lp if "rei ro pu" - c nov re t er". nO hte ehto r dnah , if th e angis l f neuqer cy is fp + fs na d uo tup t fr neuqe cy is fs' teh n
sihT t epy of p ra am rte ic ecived wi ll on w eb llac ed ap"ram cirte down- evnoc rte "r a dn the powe r g ia n becom se power atten uation.
PIN DIODE AND ITS PA PLIC TA ION:
hT e IP N di o de is a p-ty ep , intrinsic, n-type di o ed cnoi s sti gn of a narr ow layer of p- type semic tcudno or and a orran w lay re of n-type semic cudno to ,r w hti a ihtcker noiger of irtni nsic or ev ry gil htly n- od ped sem noci duc rot mat ire al iwdnas ch de eb wt een ht em.
nociliS si t eh sem ci o rotcudn onrmally used esuaceb of sti pow er nildnah g ilibapac ty dna ti off re s hgih evitsiser ly f ro the cisnirtni iger on. uB ,t on w-a-days Ga ill um Anesr id e (G aA )s is al os eb i gn used. Metal la ey rs are a tt aceh d f ro conta tc rup p so es. It s main app li ac ti no s a er in im rc owa ev stiw c ih ng dna om dula oit n.
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NIP id o ed ca ts as a mor e or l se s nidro ary edoid at feuqer n seic u otp ba out 01 0 HM z. tA hi hg freq neu ci se , ti ceases to rectify na d ht ne ac ts as a v raai b el resista n ec htiw na uqe i tnelav tiucric dna a resi ts a ecn- tlova eg ccarah t eri scits I. n ' ht e e uq vi a el nt ci cr ,tiu Land C re rpes ent t eh packa eg ni ud ctance na d capac ati cn e p p ser p ce ti ev ly. R is ht e klub semicno d cu t ro lay re dna c tcatno re tsis a .ecn R. a dn C. tneserper ht e pser ective noitcnuj ser i ats nce a dn ticapac an ec of eht cisnirtni lay re . Wh ne ht e ib as is va ir ed no ht e IP N oid de, its m ci r wo ave resi ats nce .R hc a egn s f orm a t py ical vla eu of 6 K dnu e r J evitagen saib to hrep a sp 5 Q whe n eht ib as si evitisop T. hsu , if eht edoid si monu t de ac or s s a 05 Q oc -xa ia l l ni e, it lliw not s gi nificantly load th is il ne wh ne ti si kcab - ib a ,des so aht t eht rewop f wol w lli not eb tni erfer de iw t .h How eve ,r if the edoid si now f drawro ,desaib sti re ists a ecn dr spo ngis ific tna ly to 5Q, os taht most of eht po rew si erfcel t de dna drah ly any is t nar sm ;detti th e doid e is gnitca as a s tiw ch.
ACP LP I AT OI N FO PIN DIODE AS SINGLE POLE SW TI CH:
A NIP edoid can be desu ni rehtie a ires es ro a s tnuh ocn farugi t noi ot f ro m a si gn le-op el , is ngl e-th row RF s tiw ch. Th ese ci stiucr are hs own htiw saib en t row ks eblo w. www.getmyuni.com M ci ro aw ves & Rada r 01 CE 45
nI the series c no figu ar ti no t eh s tiw hc is NO w eh n ht el d oi ed si fro aw dr Bi sa ed adn FFO nehw ti si re srev e .desaib ,tuB ni sh tnu noc f oitarugi n of for draw nisaib g ht e di do e c" u st -o ff ' the t snar sim sion and reve r se bai sin g the diode en us r se nart smissio n from inp tu ot ptuo u .t ehT DC skcolb s dluoh h vae a ev ry ol w im ep d ecna at RF o ep r gnita fqer u ne cy an d RF ekohc in rotcud s hs o dlu evah very high RF im ep dance.
laedI ly, a tiws ch shou dl have z ore sni e itr on ssol ni the ON tats e dna nif ini te a noitaunett ni eht OFF .etats Reitsila c s iw tc gnih element ,s of co ,esru user lt ni som e i sn e itr on l so s for the ON sta et an d f etini a ett un ita on for ht e OFF stat e d eu to non -ze or fro war d ib as rse istan ec . Si lim ra ly, f ro rev re se bi sa sh nu t capca it ro is not ni finite & nno - ez ro i sn er oit n loss ser tlu s. aceB us e of eht gral e brea odk wn vo egatl ( 005= lov t )s comp dera ot an anidro ry ,edoid IP N di edo nac be ib a des at hi hg tagen ive ger i no so t tah gral e .a c. signa ,l uspe r impo des on .d c. ca nn ot m ka e the ved ice forw dra b ai sed.
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F ro w dra iB as: When eht NIP oid de is f drawro ib a ,des the ac pacit sro C a dn C. a ml so t behave as op ne circu sti so t ah t the equiave l tn ci cr tiu can now be simp il fi de w reh e Rf i s ht e tot al forw dra er is st nace of ht e IP N diode gvi ne by
.. The di do e imdep a cn e Zd of the IP N diode si give n by
reveR se saib : W eh n t eh NIP edoid is ver e esr ib a des , eht ac p ca itance of eht cisnirtni layer .C becomes ngisi fic tna and rR lliw eb eht qe uiv tnela esrever ser tsi ance and ht e simp il f ei d equ vi a el nt ci cr iut for r ve e sr e bi sa ed PIN diode can be c sno t cur ted as shown. hT e diode impe ad nce Zd of ht e IPN d oi de und re re ev rs e bi sa , si th en give n by
reveR se saib : W eh n t eh NIP edoid is ver e esr ib a des , eht ac p ca itance of eht cisnirtni layer .C becomes ngisi fic a tn and rR lliw eb eht qe uiv tnela esrever ser tsi ance and ht e simp il f ei d equ vi a el nt ci cr iu t for r ve e sr e bi sa ed PIN diode can be c sno t cur ted ; hT e diode impe ad nce Zd of ht e IPN d oi de und re re ev rs e bi sa , si th en give n by
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IP N DDIO E AS PS DT S IWTC :H
elgniS - elop do elbu ht r wo )TDPS( noitca ac n eb deniatbo by u is ng a riap of NIP sedoid tie her ni s ire es nocf noitarugi ro ni s tnuh nocf noitarugi as nwohs nI. t eh resi se co nfi ug ra oit n of figu er 3 2. (9 a), when DI is f ro w dra b ai se d and Dz erv sre e ,desaib co tcenn i no is e silbats h de teb w nee RF tupni dna uptuo t I and on tuptuo ta UO PT UT II .
Wh ne the biasing cond iti on is reversed (D( rerev s e bia des and zD forw ra d bi sa ed), c no n ce tion is es at bli sh de eb ewt ne FR ni put a dn ou pt ut II.
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nI eht tnuhs noc f noitarugi nehw D3 is f awro rd aib s ,de ti eb comes s troh detiucric gniworht an nepo circ tiu ta FR in tup enil ju noitcn eud to ( IA )4 sec .noit 4D is esrever esaib d os that ti eb comes o nep c tiucri hgih( im ep d na ce ats t )e na d c oitcenno n si se t lba ish de wteb e ne FR tupni dna tuptuo .II When 3D si ever r es desaib and D4 f awro rd saib e ,d nnoc e tc i no is se t ilba shed eb t eew n RF upni t na d uopt ut I.
STHC O YKT BARRI RE DIO:DE
cS hottky ba rr ei r di edo is a s po ih scit a et d v re si no of ht e po tni -c no tac t s cili no crystal diode, whe er i n the me ta l -se im condcu t ro jnut c i no so formed is a us rfa ec ra ht re th an a point conta tc . hT e ad nav t ga e of scho ttky doi d e ov re point oc nta tc crystal d oi de is the el iimat n io n of m ironi ty ac r reir flow ni eht r esreve - saib ed noitidnoc of ht e id o .ed euD ot iht s le im oitani n of loh es, th ere is on led ay eud to loh e- le ec nort cer ombi noitan ( cihw h si tneserp in cnuj noit d )sedoi dna neh ce eht o ep r noita si fa .rets eB c esua of regral noc t ca t raea of rectifyi gn c no tact co pm ared to cr syta l diode , the f ro w dra r se si ta cn e si ewol r as al os esion . N esio f serugi as low as d3 B h va e eb en atbo i den tiw h ht ese di do es. tsuJ ekil cr tsy al edoid s, ht e sc oh ttky sedoid are la so used in itceted on na d im xing.
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ehT urtsnocc t noi of s ttohc ky id ode si sulli t tared ni f erugi (03.3 a .) hTe doid e noc sis st of n+ silicon ssbut r at e upon wh ci h a thin lay re of si cil no of 2 to 3 cimron enkciht ss is ixatipe ally .nworg hTen a ht in i gnitalusn layer of ilis c no edixoid is nworg reht m la ly. After gninepo a niw d wo t hguorh ma iks ng orp ces ,s a me lat-
sem ci o udn c rot uj itcn on si form de by ped osi gnit me lat revo SOi 2. sc ttoh ky edoid whi hc i s a ml so t id neti cal tiw h t ah t of crys tal di edo .
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R CE OMM NE DED QUTSE INO S ON NU TI - 3
1. What si “ G nnu Ef cef t ?” w hti a n ae t id ag mar exlp a ni ht e con ts ruc it nola deta sli of NUG N d i do e. 2. Exlpia n hte idereff n t mdo e s o f po are it on o f G nu n idode soc li la tor. 3. Exlpia n RWH hteory for arT sn ref el ce tr no de iv ec s. 4. Expla ni ht e two va ll ey theory m do el. 5. What era m do se of op are oit n of G nnu di do ,e ex lp ain. 6. iW ht n ae t id ag mar exlpia n hte con ts ructi no and opare noit o f AER D diode. 7. iW ht n ae t id ag mar exlpia n hte con ts ructi no and opare noit o f MITAP T oidde. 8. iW ht n ae t id ag mar exlpia n hte con ts ructi no and op re anoit o f TRA TAP T di do e. 9. iW ht n ae t id ag mar expla ni ht e c no struc it o n and poare oit n of BRA TI T oidde. 10. With nae t diag mar exlpia n hte con ts ructi no and opare noit o f S KTTOHC Y b rra i re doid e. 11. Expla ni the poare oit n of a ba is c p emara tri c mailp fi re whti uqs era wva e up pm ni g. 12. What era M ELNA Y –ROWE er la snoit ? Ho w a er ht ey su fe lu ni dnure s tandi gn pemara tr ic am ilp fi sre .