1 ti: MCH iU TN TRC TiP DNG VARICAP2Li m uTrong truyn dn v tuyn , a tn hiu c tn s thp nh m thanh ting ni i xa cn c nhng k thut iu ch a ln tn s cao, ni thu s gii iu ch thu c tn hiu m tn mong mun,gm iu ch tng t v iu ch s.Phng php iu ch tng t gm iu bin (AM) v iu ch gc (PM v FM).Mi phng php c u , nhc im ring v c dng ty vo ng dng c th.3H thng thu pht i tn c dng rng ri trong pht thanh radio FM dy tn 88-108Mhz , truyn hnh audio, ng dng qung b . do u im v kh nng chng nhiu cao ,hiu qu s dng cng sut v cht lng thu tt hn AM.Tuy nhin mch pht , thu FM cng phc tp hn AM v do gi thnh cng cao hn.ng dng FM dn dng c dng ph bin trong cc Micro khng dy. 4 ti mch FM ny ,mch pht mt tn s trong dy tn radio FM tn dng my thu radio sn c.Rt mong nhn c s ng gp kin ca cc thy c bi bo co c hon chnh hn.5Ni dung bo co:C s l thuyt FMNguyn l mch dao ngPhn tch mch dao ngPhn tch thit k mch M phng bng phn mm PspiceThc hin mch in LayoutBo co kt qu v tng ktHng pht trin67I.1.SO SNH AM V FM:iu ch bin AM:Cng sut sng mang khng ti tin ln ,v ch. Cng sut cao tn ti tin nh ca hai bin nh nhau v ph thuc h s iu ch mA Hiu sut km (P1 bin/Ptotal) Tnh chng nhiu km do thng tin nm bin v nhiu trng tc ng ln bin D thc hin AM v my thu gii iu ch n gin ,r tin AM dng trong pht thanh qung b MW-SW.Pht tn s tng i thp (vi trm KHz) do tn s cao nhiu cao tn xut hin nhiu. BW nh do ch c 2 thnh phn sideband fc fm v fc + fmDng c bit ca i tn.8 I.2.IU CH TN S:S khi h thng thu pht:9iu ch tn s to ra s lng ln sideband 2 pha ca sng mang cao tnTn hiu FM , h s iu ch v bng thng u ph thuc vo bin v tn s ca tn hiu iu ch m(t).So snh vi AM , FM c h s iu ch ln hn , BW ln hn v kh nng loi nhiu tt hn. 10Biu thcGi s tn hiu iu ch

Sng mang c dng Tn hiu FM c dng:trong Ec:bin sng mangwc:tn s sng mangwm:tn s tn hiu iu chmf:h s iu chmf = f/fm( ) ( )m mm t .sin w t V ( ) ( )c c cv tV .sin w t ( )FM c c f mV E .sin w t m .sin w t +1 ]ff m m mmk .v / w w / w 11Pha y : Tn s tc thi :Sng mang dng sine c iu ch bi tn hiu iu ch m(t) dng sine , bin m(t) ti mi thi im lm thay i tn s tn hiu ng ra so vi sng mang ban u , trong khi bin khng i.( ) ( )c m mt w t w / w .s i n w t + ( ) ( )c mw t d t / d t w w .s i n w t + 12 Tn hiu FM c phn tch hm Bessel: Cc h s Bessel Jn trong khong 0,0 n +1,0/-1,0 ti mi tn .Hai di bn l ngc pha nhau , hai di bn chn ng pha. ( ) ( )( ) ( )( ) ( )( ) ( )( ) ( )01234 c m c m.{ 2 2 3 3J sin w 4w tsin w 4w t..}FM c cc m c mc m c mc m c mv t E J sin wtJ sin ww t sin w w tJ sin w w t sin w w tJ sin w w t sin w w t ++ +1 ]+ + +1 ]+ +1 ]+ + +1 ]1314 Bng thng FM:Cng sut tn hiu FM gii hn cc h s Bessel chim xp x 98% cng sut FM.Cc vch ph bc cao hn c bin rt nh c th b qua.( )mf m mBW 2(f f ) 2 m .ff + +15 I.3.DY TN S FM THNG DNG:ng dng FM :Pht thanh qung b phi thng mi 88-90MhzPht thanh thng mi 90-108MhzTruyn hnh audio(WFM)Cc dch v thng tin cng cng (cnh st , cu ha ,) 30-50Mhz,450-470Mhz , 800Mhz(NBFM)Cc ng dng khc1617 II.1.C TNH MCH DAO NG:Mch dao ng thng dng tn s cao, khng dng tn s thp. Hu ht u s dng cun dy , do nu dng tn s thp kch thc cun dy rt ln khng c tnh kinh t.18 II.2.CC THNH PHN C BN CA B DAO NG:19iu kin dao ng ti thiu ,tiu chun Barkhausen:Tn hiu hi tip ng vo phi c cng pha vi tn hiu ng vo ban u (hi tip dng ) v phi c bin nht nh .20 c tn hiu hi tip n ng vo cng pha vi tn hiu vo ban u.Mng L-C phi to ra mt lchpha 180 . Bn thn transistor nu ly ng ra t cc C to ra lch pha 180 so vi tn hiu vo , cn phi to lch pha 180 t cc C . Mng L-C s lm iu ny v kt qu l to thnh hi tip dng.21II.3.S TRI TN S B DAO NG :S tri tn s do bn thn TransistorS tri do mng L-C : hn ch s dch tn ny ( d rt nh ):Cn thn trong thit k mch L-C.Bao bc phn mch dao ng n nh nhit .iu chnh nhit ca phn dao ng.B chnh nhit ( c th dng diod, bn dn, ).Gn cht cc kinh kin ngn s di chuyn ca linh kin do va chm hay rung ng .22II.4.CC DNG MCH DAO NG:II.4.1.Dao ng ghp bin p :23II.4.1.Dao ng ghp bin p :Transistor to mt dch pha 180 ng ra , do yu cu mch hi tip phi to c dch pha 180 .Trong dng mch ny mch hi tip c dng l bin p .Cun dy s cp ca bin p v t C s quyt nh tn s dao ng ca mch.Tn hiu hi tip c iu khin bi t s k ca bin p.12oscFLC 24 II.4.2.Mch dao ng Colpitts:25II.4.2.Mch dao ng Colpitts:Tn hiu hi tip v cc B iu khin bi t s 2 t C1 v C2 nh bin dao ng t c ti im m mng to ra dch pha 1800 , ti dao ng xy ra.Cun cm hay t in c th thay i.T C2 thng c gi tr nh hn C1,v thng l t c th thay i tr s c.12oscequivFLC 26 II.4.3. Mch dao ng Hartley:L 10C0L 2 R L27II.4.3. Mch dao ng Hartley:Tn hiu hi tip v cc B ca transistor iu khin bi t s L1:L2 .T s ny ,cng vi tr khng vo ca transistor s xc nh tr khng vo ca mch cng hng .Bn cnh ,t s tr khng ny v ti quyt nh li ti thiu cn thit cho dao ng.Thng thng th L1 nh hn L2 .1 212 ( )oscFL LC +28 II.4.4.Dao ng thch anh: Tn s cao , n nh caoMch in tng ng thch anh gm nhiu nhnh.Tng ng t in hay cun dy.C tn s cng hng ni tip gn bng tn s cng hng song song.QTA=XLT/rT rt ln c.Gi tr LT,CT ph thuc kch c,chiu ct thch anh.5 610 ,1029II.5. N NH TN S B DAO NG: n nh tn s tng i :C hai loi bt n nh tn s : Thi gian di : thay i tn s t t do bt n nhit , p sut , m , rung c hc , ngun . Thi gian ngn : thay i tn s trong thi gian ngn - mt hay vi chu k tn hiu do nhiu nhit , nhiu shot. bt n thi gian ngn gim khi h s phm cht Q mch cng hng tng (Q ln bng thng hp , chn lc tn s cao hn). Tn s dao ng mch cng hng f0 . Di tc ng cc yu t gy si dng thng s L,C mt lng.00 0f ff 3031III.1.BIU THC TON:***oviVAV***foVBV li khuch i in p khng hi tip:H s truyn t mch hi tip :32Xt hi tip dng:* * *o i vV V A * * * * * * * * * * * *0( ) ( )v f v v f os f s v sV V A V B V A A V A B V + + +*0sV * *1v fA B c t dao ng th iu kin * *1v fA B cn gi l tiu chun Barkhausen.* *1v fA B tc l mch khuch i b c suy hao ca mch hi tip .* *1v fA B < mch khng dao ng.33III.2.CC MCH DAO NG L-C:Z LL 1C 1C 2Z LL 1C 1C 21 100 30 1 0 2101 2.31 2LC CC CLC C +Hnh III. 4 Mch dao ng Colpitts dng BJT hay FET34III.2.CC MCH DAO NG L-C:L 1Z LC 3L 2L 1Z LC 3L 2Hnh III. 5 Mch dao ng Harley (ba im in cm )0 1 0 20 303 1 2101.( )L LCC L L + +35III.2.CC MCH DAO NG L-C:C 3L 3C 1 Z LC 2C 3L 3C 1 Z LC 2Hnh III. 6 Mch dao ng Clapp0 30 303 3101LCLC 0 30 1 0 2 0 31 1 10 LC C C 3 1 2C C v C =36III.2.CC MCH DAO NG L-C:So snh gia cc loi mch dao ng th Clapp cho n nh cao.Do mch dao ng Clapp ch ph thuc vo 2 phn t ,gim c nh hng t k sinh tn s cao. Th n Colpitt ri Harley.Mch dao ng L-C i hi cc linh kin cn c cht lng tt, sai s nh ,nhiu thp.37III.3.MCH VCO (voltage-controlled oscillator):3839 IV.1.S KHI: Phng php iu ch tn s trc tip n gin nht l lm thay i tn s dao ng.C th dng mt micro in dung thay i theo in p a vo ,dng diode bin dung , s dng vi mch VCO,hoc iu tn da trn t in k sinh tip xc transistor thay i theo in p phn cc..Phng php iu ch FM y c thc hin da trn nguyn tc iu ch FM trc tip dng varicap lm thay i tn s dao ng (tng t VCO) , v tn s ng ra nm trong dy tn FM radio.40Phn tch s khi:41Mt s dng mch iu ch FM trc tip:Mch pht FM s dng 2 TransistorMch dng Op-amp khuch i m tn Mch trn iu ch FM bng Varicap Mch kt hp L-C thch anh cho n nh caoiu ch in khng trn c s khuch i CE lp A42IV.2.S NGUYN L:0R 2R 1 0C 3C 1 00L 3Q 2R 3R 5C 1 1R 9L 1BBY31Q 3Q 2 S C 1 8 1 5R 1 2R 1 5C 5Q 1B C 5 4 7 CM K 1M I C R O P H O N E12L 4L 5C 2C 1R 6R 1 1C 60R 1 4R 1R 1 3V C C0C 1 5R 71 0R 4L 2C 8C 743IV.3.TNH TON TNG DAO NG:Z e C 1R e qC 2 L 12 211 21.eeq eZR ZpCC C _ + ,C 2 C 51 nV a r i c a pL 1V C CR 21 0 kR 31 . 5 k0C 3 C 1Q 1B C 5 4 7 CC 41 uR 11 0 k0Hnh IV.7 Mch dao ng Colpitts44R1 = 10kR2 = 10kR3 = 1kVCC = 12VTransistor Q1: Cc t C1 = 68pF ,C2 = 2nF,C3 = 47pF Cho in p phn cc ngc ca varicap l 5V nn Cv =8pF T C4 ng vai tr t lin lc ni vi tn sau c in dung ln.45Ch DC:1 211 2/ / 5. 6( )5.12( )* 6.88( )1(5.12 ; 6.88 )bbbbbbCQbbeCEQ CQ eR R R kRV VCC VR RV VI mARRhfeV VCC I R VQ mA V + + 46S tng ng:25CQhfehieI = 0.73k' b er hie = 0.73k4721211 2C ffo CX VCBV X C C +.ov m LfVA g ZV '1mb ehfeghib r H s truyn t mch hi tip: =0.033 li khuch i in p khng hi tip:vi=0.21

48=2244.15 (t cng thc tnh tr khng khung cng hng)21 21( / / ).eq e C CR hib RC _ + ,/ /L eq oZ R Z .( / / )v m eq oA g R Z : . 1f vm BA11 2. .( / / ) 1m eq oCg R ZC C +Vy: mch c th dao ng c cn chn gi tr tr khng ti ln tha mn iu kin dao ng.49( )e q oR / / Z 1 4 4 . 3 . 1.5v fA B 216.5239.5oZ 239.5oZ 240oZ Chn Req//Zo= Nh vy : phi c Chn 50 Tn s hot ng F = 90MHzCc t C1 = 68pF ,C2 = 2nF,C3 = 47pF Cho in p phn cc ngc ca varicap l 5V nn Cv =8pF Nhn vo pha Zo : o LZ R tan/ /Cv amZ Ztan Cv amZ Z =Do nhnh c tr khng ln nht khi chn Zamtan= 4.7ktan/ /Cv amZ Z220.8 87.3 ( )o = tan 3( / / )Cv am CZ Z Z + 258.4 87.69 ( )o = tha240oZ Chn RL=500 Ohm51Cc thng s yu cu i vi cc tn ghp ni vi mch dao ng:Tr khng vo tng khuch i Cng Sut cao tn : RL=500 OhmTr khng ra tng khuch i m tn : Zamtan = 4.7k52IV.4.TNH TON CC PHN T MCH DAO NG:Phn tch mch dao ng Colpitts VCO with varicap53S tng ng:Gi s : min max vC C C in dung tng ng Ca, Cb:1 21 233/ /avbva b total a bC CCC CC CCC CC C C C C++ +5412osctotalFLC oo o of fff f 55Tnh ton cun dy ng vi tn s dao ng mong mun :Q 1B C 5 4 7 CV a r i c a pR 21 0 k1 2 V d cC 4C v0L 10C 51 n0C 16 8 pC 22 n0R 51 kR 11 0 k0C 34 7 p0Cc gi tr c:Cc t C1 = 68pF ,C2 = 2nF,C3 = 47pF in p phn cc ngc ca varicap l 5V nn Cv =8pF Yu cu thit k ti tn s 90MHz56Tnh ton cun dy ng vi tn s dao ng mong mun := 65.76pF= 6.84pF= 72.6pF6210.043 10 43.(2 )total oscL H nHC F 1 21 2aC CCC C+33vbvC CCC C+total a bC C C +57Q 1B C 5 4 7 CV a r i c a pR 21 0 k1 2 V d cC 4C v0L 10 . 0 4 3 u0C 51 n0C 16 8 pC 22 n0R 51 kR 11 0 k0C 34 7 p058IV.5.TN KHUCH I M TN: IV.5.1.Phn tch:M K 1M I C R O P H O N E12V C CR 1 0C 1 1C 1 00R 9R 1 2R 1 4Q 3Q 2 S C 1 8 1 5R 1 1 R 1 30in tr R9 phn cc cho microT C10 l t lin lc T bypass C11Transistor C1815 c hfe = 100, V= 0.7V59Phn cc DC :98.2 R k 1147 R k 1010 R k 13R12128.252.11.09( )bbbbCQbVCC VR kV VV VI mARRhfe +12 13*( ) 5CEQ CQV VCC I R R V + 135.22 R k Chn: lc chn ty vo p ra cc C

(theo yu cu thit k)60Ch AC:S tng ng 252.3CQhfehie kI Gi Ri l ni tr ngun Vi, gi s Ri = 2k61Ch AC:131. . . . 107.46/ /o o b bbvi b i i bb bbV V i RA hfe RV i V R R hie R hie + +14/ / 1.85.22i bboZ R hie kZ R k Gi s tn hiu t micro a vo c bin Vi = 20mV, qua mch khuch i s c bin Vo = 2.15V . in p ny c t ln varicap lm in dung thay i.6263Do ch cn mch thu trong dy tn nghe c ca tai ngi t 20Hz-20KHz.Phn tch trn ng cho trng hp tng qut cho . c c tn s ct nh mong mun cn thm t C mc vo BC , t bypass C11 c gi tr gii hn.64S nguyn l tr thnhTransistor C1815 c Cbc = 2pF , hfe=100hie = rbe = 2.3kRbb = 8.25k , Ri = 2k65S tng ng tn s thp:0( ) .v vmpsA s As++vmA 107.46 011121.Chfe Rhfe 12 12* . R hfe R 1111*CChfe=120k 661pci iR C ( )12/ / / / *ci i bbR R R hie R +=3.78k11*iC C 2 202 2 .20L p 11* C 11C 2.1x10-6210.31uF67S tng ng tn s cao:68'mb ehfegr 0.04313.omiVK g RV -224.46( )1 131 .m tdY g R sC + ' td b cC C C +( )131 . .M m tdC g R C +1( ) .1ov vmpsA s As++1pMRC 69( )'/ / / /i bb b eR R R r 0.95k221 1 12H p o _ _ , ,H P 2 .20000 MC tdC C 8.38nF37.2pF35.2pF7071 IV.5.2. di tn:72ng vi in p phn cc ngc VR=5V CV=8pFKhi c p xoay chiu bin ~2V in dung bin thin trong khong 6pF < CV < 10pFCV = 8pFCt = 72.6pFF = 90MHzCV = 6pFCt = 71.08pFF = 91.1MHzCV = 10pFCt = 74.01pFF = 89.2 MHz di tn :0.9 f MHz 73 IV.5.3.Mt s loi micro:Trong s mch trn ,ngun p Vi a vo mch khuch i.Ngun p l micro chuyn i tn hiu m thanh dao ng c hc sang tn hiu in p c bin nh (khong vi chc mV) v tr khng ra khc nhau ty mi loi micro.74Micro in dung (Condensor, capacitor, electrostatic microphones):7576MIC in dung hot ng nh mt ci bn trt t in, dng t in c khong cch 2 bn t thay i c.Dao ng c lm thay i khong cch gia 2 bn t. ly tn hiu audio t loi MIC ny, microphone phi c phn cc DC, t in c Q (in tch) thay i.U l in p phn cc DC. in p qua t s thay i vi dao ng ca khng kh.in dung C t l nghch vi khong cch gia 2 bn cc.in p ly ra t R ng vi mch lc thng cao .Trong khong thi gian in dung thay i thi hng RC ca mch lc cng thay i .Nh vy in p ng ra thay i.in p ny c th c a qua tng khuch i m tng bin .77Micro in ng (Dynamic microphones):78Mic hot ng theo cun dy in t.Mic di chuyn cun dy t trong t trng ca nam chm khi c rung ng ln mng.Theo nguyn tc cm ng in t, mt s di chuyn nh cun dy trong vng t trng sinh ra dng thay i trong cun dy thng qua vng dy t trong t trng. Mic in ng khng cn phn cc ban u, c nhy cao ,tr khng ra nh nn khng cn phi hp tr khng trc khi a vo tn khuch i m tn.Mt mng chn khng p ng tt cho tt c cc thnh phn tn s m tn.Mt vi micro dng a mng ly cc thnh phn audio khc nhau.Vic kt hp tn hiu a mng trc tip rt kh lm cho gi thnh tr nn t hn.79Micro carbon:80Micro cabon thng c dng trong cc in thoi cm tay, l mt khi gm cc tinh th cacbon p gia 2 tm kim loi. Mt in p c t gia 2 tm kim loi ny gy ra mt dng tri nh qua lp cacbon. Mt trong 2 mng chn (ming kim loi ),dao ng vi sng m truyn ti, to mt p lc thay i ln lp cacbon. p sut ny lm bin dng khi cacbon,gy tc dng ln lp tip xc gia khi cacbon vi mng kim loi thay i v iu ny lm cho in tr ca khi cacbon thay i.S thay i in tr lm cho in p gia 2 mng kim loi thay i, dng tri qua micro cng b thay i, sinh ra tn hiu in.Micro cacbon dng trong in thoi, chng c cht lng m thanh thp v rt hn ch v tn s.81Dng loa nh l microMicro ribbon (bng) ,thch anh hay gm c bin in p ra nh nhng tr khng rt ln dng trong thip nhc,..82IV.6.KHUCH I CNG SUT CAO TN: Lp A:= 180oLp B:= 90oLp C:< 90oLp AB :90o nn khung cng hng c dng892. 1 18.710.033eqL AARX RRL H 824.05173.52eqCeqARXRRC pF 90S tng ng 91'25 1501.342.8b er k '''''0.112( )(1 . ). (1 0.112 45) 2.6 15.704/ / / // / 1.02/ /. 0.78/ /mM m eq b ci b b e Mbb b ebb b evm m eqi bb b eg sC g R C pFZ R r CR r kR rA g RR R r + + +92R710L333uHR54.7kQ2R675kRin5.6kL20.033u12VdcR152200Vin0C1510uC873.5pC710uL433uH93S nguyn l hon chnh:94Dng nhiu ng voCc ngun nhiu :nhiu nhit,nhiu bn dn Nhiu trong khuch i bn dn95Cc ngun nhiu2 2 22 1 i i bE I R 212 . .i bI q IB Nhiu dng shot do tip xc p-n ng ra a v ng vo qua in p214i bE kTBR Nhiu tip xc p-n ng voNhiu nhit trn tr RbNhiu do dng tip xc p-n gy ra trn in tr Rb2022 . .cI q IB 96p nhiu do dng shot ng ra gy ra trn ti RL2 2 202 02 LV I R 2 2 2 24 2 2 / 4 / ( . )i b b b c m m LE kTBR qI BR qI Bg kTB g R + + +Tng in p nhiu ng vo qua Tng dng nhiu ng vo cc B2 2 2 2 2121/ .(2 .(4 2 2 / 4 / ( . ))i i b b b b b c m m LbI E R B qI kTBR qI BR qI B g kTB g RR+ + + + +9798 V.1.M PHNG TNG KHUCH I M TN:S nguyn lR1010kR121.2kR1147kC11100u0V1FREQ = 2KhzVAMPL = 100mVVOFF = 0vC101uR135.22kQ3Q2SC1815R98.2k0V212Vdc99M phng phn cc DC:V 1F R E Q = 2 K h zV A M P L = 1 0 0 m VV O F F = 0 v1 . 4 6 3 m A0R 98 . 2 k1 . 4 6 3 m AC 1 11 0 0 0 uR 1 35 . 2 2 k1 . 0 9 2 m AR 1 21 . 2 k1 . 0 9 9 m AQ 3Q 2 S C 1 8 1 57 . 1 5 9 u A1 . 0 9 2 m A- 1 . 0 9 9 m AR 1 01 0 k2 0 4 . 6 u AC 1 01 0 0 0 uV 21 2 V d c2 . 7 6 7 m AR 1 14 7 k2 1 1 . 8 u A0V100Kt qu :L thuyt ( phn IV.5.1)M phngICQ(mA) 1.09 1.092VCEQ(V) 5 4.98101M phng ch AC:C 1 11 0 0 0 uR 1 14 7 kR 1 35 . 2 2 k R 98 . 2 k0R 1 21 . 2 kV 1F R E Q = 2 K h zV A M P L = 1 0 m VV O F F = 0 vQ 3Q 2 S C 1 8 1 5V 21 2 V d cC 1 01 0 0 0 uR 1 01 0 k0V102-Tn hiu vo l sng sin ,bin 10mV ,tn s 2KHz-Quan st dng sng ng ra ti cc C ca transistor103L thuytM phng Av-107.46 -200104Nhn xt:-Phn cc DC gn ging vi l thuyt-Tn hiu ng ra ngc pha vi ng vo- Bin in p ra Vom = 2V - li in p lch nhiu so vi tnh ton do trong l thuyt c cho trc tr khng ngun.105V.2.M PHNG TNG DAO NG : Qu trnh pht sinh dao ng l do nhiu trong linh kin bn dn , c hi tip v ng vo sau mt khong thi gian ngn s t c bin v tn s dao ng n nh.Tuy nhin cc linh kin trong th vin ca phn mm Pspice khng c cc c tnh ngu nhin nh cc linh kin thc t v vy cc iu kin dao ng c khc so vi l thuyt.Do vy khi m phng mch dao ng , mch nguyn l khc so vi l thuyt. Do transistor trong m phng khng to c nhiu do mch dao ng cn phi to gi tr in p ban u cho 2 t C1 ,C2 .T s np x v hi tip v ng vo v sau khong thi gian ngn s to c dao ng n nh. Cn chn t s in dung 2 t C1 , C2 ph hp .in dung mi t phi ln m bo khng lm mt dao ng. Dng in p ng ra ngc li vi l thuyt. Ban u rt ln sau gim dn n mc n nh.Bin in p ng ra cn quyt nh bi ti RL . Tr khng ti nh qu cng khng dao ng c. Do in dung t ln nn c tn s dao ng cao th cun dy c in cm rt nh, kh thi cng trn thc t.Tn s dao ng c iu chnh bng cch thay i gi tr in cm cun dy.106S nguyn l:107Tnh ton: Dng varicap MV2109 c c tuyn in dung theo in p -Ti in p 5V , in dung varicap l Cv = 35pF -Ngun tn hiu vo c bin 10mV.Ng ra tng khuch i m tn theo nh m phng c li Av = -200 .Bin l 2 V. Khi in p a vo phn cc varicap l 3V, CV1 = 40pF Khi in p a vo phn cc varicap l 7V, CV2 = 30pF Cc thng s : C1 = 560p108C2 = 8nC3 = 10pCV = 35p (5V)L1 = 0.007u1 21 233523.67.78/ / 531.14avbva b total a bC CC pC CC CC pC CC C C C C p + + + 182.542osctotalF MHzLC 109 di tn:CV1 = 40pFCV2 = 30pF 182.522osctotalF MHzLC 182.63290osctotalF MHzLCf KHz 110M phng:Min thi gian111112113114VI.THC HIN MCH IN LAYOUT:Transistor Q1 dng cc transistor cao tn c tn s wT ln m bo bin tn hiu khng b gim qu nhiu.Mt s loi nh l BC547C , BF199 , 2SC9018 , TSDF2020W , BFR95 ,....Diode varicap 1sv101 , MV2109 , BBY31 , BB814 , 115S mch in:116Thi cng cun dy:Theo s nguyn l phn IV ( Hnh IV.24 ).Cun dy L1 = 0.043uH ,v L2 = 0.033uH.Cng thc tnh cun dy li khng kh n lp :2 2( )18 40d nL Hd l +( 0.4 ) l d l : chiu di cun dy (inch)n : s vng dyd : ng knh cun dy (inch)L : in cm tnh bng H Ngoi ra , c th dng phn mm tnh cun dycoilmaestro , Air Core Inductor Coil Inductance Calculator ,. kt qu kh chnh xc.117VII.BO CO KT QU V NH GI : VII.1.CC BC TIN HNH:Tm hiu l thuyt v iu ch tn s.Nguyn l mch dao ng. Cc loi mch dao ng v cc thnh phn c bn. Tnh ton di tn Thit k cc tng , tr khng vo ra phi hp vi cc tng khc.Tm linh kin ph hp vi yu cu . Thit k mch phi hp tr khng a ra anten. Tm hiu mt s loi micro thng dng. M phng mch dao ng. Thc hin mch in v thc hin cun dy theo tn s dao ng mong mun.nh gi kt qu cng nh kinh nghim rt ra c trong qu trnh thc hin ti.118 VII.2.NH GI KT QU:Qu trnh thit k mch nguyn l theo cc yu cu ra Tuy nhin khi thc hin mch in khng tm c linh kin c cht lng nh yu cu Cun dy khng chnh xc nh yu cu thit k nn tn s ng ra ca mch dao ng khng nh tnh ton 119 VII.3.HNG PHT TRIN: ti mch iu tn dng varicap l mt ti c in.nh gi li l thuyt iu ch FM .Qua tm hiucch thit k mt b dao ng _ phn quan trng trong cc mch iu ch ,gii iu ch ,i tn ,cch ghp ni gia cc tn tha mn iu kin dao ng.120Ti liu tham khoL Tin Thng, Mch in T 1,2 Hong nh Chin, Mch in T Thng Tin V nh Thnh , Nguyn l thng tin tng t - s James K. Hardy, Electronic Communications Technology , Prentice/Hall International Inc.Cc trang web:http://electronics-diy.com/index.php http://www.fas.org/man/dod-101/navy/docs/es310/syllabus.htm(iu ch FM) http://www.daycounter.com/Calculators/(tnh ton cun dy) http://www.qsl.net/wa2whv/bta-500r.shtmlhttp://en.wikipedia.org/wiki/Microphonehttp://www.datasheetcatalog.com