Bi tp chng IBi 1: a. in tr: lam-vng-cam-en-vng kim: 643 5%b. t in: 0.05/500: c in dung l 0.05 F v c in p 1 chiu l 500 Vdc.104F/250V : c in dung l 0.1F 1% v c in p 1 chiu l 250 Vdc.c. Cun cm: Lc vng kim vng kim: 5.2 H 5%Cam tm lam bch kim: 37 H 10%Bi 2:a.in tr : Tm cam lc khng mu c gi tr l: 7300 K 20%.b. T in: 0.05/150: c in dung l 0.05 F v c in p 1 chiu l 150 Vdc.107J/150V: c in dung l 100 F 5% v c in p 1 chiu 150Vdc.c. Cun cm: Cam - bch kim vng kim: 0.32 H 5%.Vng - tm - vng kim: 470 H 5%.Bi 3:a.in tr: Tm lc - cam vng kim c gi tr: 752 K 5%.b. T in: 0.03/200: c in dung l 0.03 F v c in p 1 chiu l 200 Vdc106K/150V: c in dung l 10F 10% v c in p 1 chiu 150 Vdcc. Cun cm: - cam bch kim vng kim: 0.23 H 5%Lc tm - vng kim: 5700 H 5%Bi 4:a.in tr: Vng - en lam vng kim c gi tr l: 420 M 5%.b. T in: 0.01/150: c in dung l 0.01 F v c in p 1 chiu l 150 Vdc.106M/200V: c in dung l 10F 20% v c in p 1 chiu l 200 Vdc.c. Cun cm: Trng tm vng kim bch kim: 9.7 H 10%.Lam - xm bch kim: 6200 H 10%.Bi 5:a.in tr: Tm xm - nu vng kim c gi tr l: 7820 5%.b. T in: 0.05/100: c in dung l 0.05 F v c in p 1 chiu l 100 Vdc.105J/50V: c in dung l 1 F 5% v c in p 1 chiu l 50 Vdc.c. Cun cm: Lam - vng kim bch kim: 6.2 H 10%.Lam tm - vng kim: 6700 H 5%.Bi 6:a.in tr: Lc trng bch kim khng mu c gi tr l: 0.59 20%.b. T in: 0.08/100: c gi tr in dung l 0.08F v c in p 1 chiu l 100 Vdc.107J/150V: c gi tr in dung l 100 F 5% v c in p 1 chiu l 150 Vdcc. Cun cm: Lam - - bch kim vng kim: 0.62 H 5%.Lam tm - vng kim: 6700 H 5%.

Bi tp chng 2:

Bi 2:a) Ta c : E - UD = I.R S tng ngc) Ta c : I

Bi 3:Gii:a)S tng ng: E UD = ID.R ID=Ura=ID.R=1.95mA.2,2k= 4,3 V

b) S tng ng : E - UD = I ( R1+ R2 ) I =

Bi 4:Gii:a) S tng ng: E - UD1 UD2 = I ( R1 + R2 ) I = Ura = I.R2 = 4,75mA.2k = 9,5 V

b) S tng ng: E - UD = I ( R1 + R2 ) I = = 3,27 mA Ura = I.R2 = 3,27mA.4,7k = 15,37 VBi 5:

a) S tng ng: E - UD = I ( R1 + R2 ) E = UD + I ( R1 + R2 ) = 0,7V + 10mA.( 2,2k + 1,2k ) = 34,7 VUra = I.R2 =10mA.1,2k = 12 Vb) S tng ng: E E2 UD = I.RI = = 3,57 mAUra = UD E2 = 0,7V + 5V = 5,7VBi 6:

a) S tng ng: E - UD1 = I.RI = = 2,34 mAUra1 = I.R + UD1 = 2,34mA. 4,7k + 0,7V = 11,7 VUra2 = UD2 = 0,3 Vb) S tng ng: E - UD1 UD2 = I. ( R1 + R2 ) I = = 2,44 mA Ura1 = I.R1 + UD1 + UD2 = 2,44mA. 1,2k + 0,3V + 0,7V = 3,93 VUra2 = I.R2 = 2,44mA. 3,3k = 8,05 VBi 7:

a) S tng ng: E - UD = I.R I = Ura = I.R = 19,3 Vdng in qua diode : ID1 = ID2 =I/2 b) S tng ng : E1 E2 UD = I.RI = = 8,77 mAUra = I.R = 8,77mA. 2,2k = 19,3 V

Bi 9:Gii:S tng ng: in p ra:Ura = E UD = 5V 0,7V = 4,3 V Ira = Ura/R = = 4,3 mA

Bi 10:Gii:S tng ng: in p ra chnh l in p thng cho diode D2V bng UD2. Vy ta c Ura = UD2 = 0,7 V

Bi 11:A, S tng ng: Diode phn cc ngc, h mchDo Ura = 0 V

B, Gii:S tng ng: in p ra ra :Ura = E Ud1 = 5V 0,7V = 4,3 V

Bi 15:

Bi 16:Gii:a) Ta c:Ut = Uz = 10VIt = Ut/Rt =10V/180V =5,5 mAIR = Uv/( Rs + Rt ) = 20V/( 220 +180 ) =50 mAIzmax = Pzmax/Uz = 400mW/10V= 40 mAb) Is = ( 20V 10V )/220 = 45,45 mAItmin= 5,5 mA => Rtmax = 10V/5,5mA = 1.8kItmax = 45,45 mA => Rtmin = 10V/45,45mA =220 mch lun trng thi n p th:220 < Rt< 1.8kBi 17:Ut = Uz = 8 VIzmax = Pzmax/UZ = 400mW/8V = 50 mAChn Izmin=Izmax = 5 mAIt = Ut/Rt = 8V/0,22k = 36,36 mAKhong bin i in p vo in p ra trn ti lun n nh:Uvmin Uv UvmaxUz + Rs.( Izmin + It ) Uv Uz + Rs.( Izmax + It )8V + 91( 5mA + 36,36mA ) Uv 8V + 91( 50mA + 36,36mA )11,76V UV 16,86VBi 18:Bi giia) Dng in vo +UBEORC+EUraUVhnh 2.11IV = IB = Dng in ra:Ira = IC = IB = 50.0,1 = 5mA in p ra:Ura = Ira.Rra = ICRC = 5.10-3.5.103 = 25 Vb) H s khuch i in p

KU =

Bi 19:Bi gii a) in tr vo tnh

b) in tr vo ng RV

c) H s khuch i dng mt chiu

d) H s khuch i dng xoay chiu .

Tm tng ng trn c tuyn ra

mA; mA

Bi 20:Bi gii a) Dng in mt chiu chy trong mch nh ch dn trong hnh 2-14.IE = IC+ IBb) in tr to thin p R1 c xc nh.

c) Tnh in tr RC

d) in p UC so vi im mass chnh l in p UCEO

Bi 21:Bi gii a) Xc nh REURE = IEO.RE = 1V

Suy ra: in tr R1

in tr RC

ICO.RC = E UCEO -

Suy ra: b) in p UC = E ICO.RC = 10 5.10-3.800 = 6 V

hay UC = UCEO + = 5+1 = 6 V

in p UB = UBEO + = 0,6 +1= 1,6 V

Bi 22:Bi gii a) C th coi IEO = ICO ICO( RE + RC) = E - UCEO

Suy ra:

- Dng tnh baz IBO:

- Thin p

Vb) Ta im lm vic tnh O: ICO = 1mA; UCEO = 4V. dng ng ti mt chiu cn xc nh mt im na. T biu thc phng trnh ng ti mt chiu.

Cho IC = 0 Ura = E = 10V ( im A trn trc honh ) ni qua im A v O, ta c ng ti mt chiu R=Bi 23:Bi gii a) RGRSRD+EU.raUVhnh 2.19in tr RS c xc nh theo biu thc:

b) Thin p

( y ) c) in p UD

Bi 24:

RSR2R1RDhnh 2.21UraUV+EBi giia) UGSO = UG USO UG = UGSO + USO = -2 +3,5 = 1,5 VV dng IG = 0 nn c th vit

Suy ra

Thay s: b) Dng IDO = 5mAng vi UGSO = -2V ( xc nh trn th 2-21b).Bi 25:Bi gii a) in p: UD = E IDORD = 12 5.10-3.1,2.103 = 6 V b) in tr RS.

a) Khi in p vo UGS thay i trong phm vi 2V 0,5V, xc nh trn th 2-2b dng ID thay i t 2,5mA n 6,25mA, nh vy bin thin dng ID t nh-nhID = 6,25 2,5 = 3,75mAin p ra ( nh nh) s bin thinUra = IDRD = 3,75.10-3.1,2.10-3 = 4,5 VH s khuch i in p

Bi 26:

RGRSRDRt+EUraUVhnh 2.23Bi giia) in tr ti xoay chiu R

b) H dn ti gc:

hay H dn ti im UGS = -2V.

c) Tnh h s khuch i

d) Xc nh in p ra

V

CHNG 3: CU KIN QUANG IN TCu 1: Trnh by cu to v nguyn l hot ng ca LED ch th?Tr Li:a) Cu to:it pht quang gm c mt lp tip xc P-N v hai chn cc ant (A), catt (K). Ant c ni vi bn dn loi P, cn catt c ni vi bn dn loi N.Hnh di m t m hnh cu to ca LED v k hiu trong cc s mch.M hnh cu to v k hiu ca LEDb) Nguyn l lm vic:S nguyn l u LED m t trong hnh diS nguyn l ca LEDKhi LED phn cc thun, cc ht dn a s khuch tn t qua tip xc P-N, chng gp nhau s ti hp v cc photon c pht sinh. Tc ti hp trong qu trnh bc x t pht ny t l vi nng in t trong phn bn dn P v nng l trng trong phn bn dn N. y l cc ht dn thiu s trong cht bn dn. Nh vy, tng s photon bc x ra cn phi gia tng nng ht dn thiu s trong cc phn bn dn. Cng dng in ca it t l vi nng ht dn c "chch" vo cc phn bn dn, do cng pht quang ca LED t l vi cng dng in qua it.Nh vy LED c kh nng bin i tn hiu in thnh tn hiu quang, nn n c coi l dng c pht quang.in p phn cc cho LED gn bng rng vng cm ca vt liu, do , cc LED bc x cc bc sng khc nhau s c ch to t cc vt liu bn dn c rng vng cm khc nhau v in p phn cc cho chng cng khc nhau. Tuy nhin LED c in p phn cc thun tng i cao (khong t 1,6 v n 3 v) v c in p ngc cho php tng i thp (khong t 3 v n 5 v).

Cu 2: Trnh by cu to v nguyn l hot ng ca led hng ngoaij?Cu to: LED hng ngoi c bn l ging cc LED ch th. bc x nh sng hng ngoi, LED hng ngoi c ch to t vt liu Galium Asenit (GaAs) vi rng vng cm EG = 1,43 eV tng ng vi bc x bc sng khong 900nm.Hnh di m t cu trc ca mt LED hng ngoi bc x nh sng 950nm.Cu trc ca LED hng ngoi bc x bc sng 950nmTrong phn epitaxy lng trong sut GaAs (N) to mt lp tinh th c tnh cht lng tnh vi tp cht Silic l GaAsSi (N) v mt tip xc P-N c hnh thnh. Vi s pha tp cht Silic ta c bc x vi bc sng 950 nm Mt di ca LED c mi nhn to thnh mt gng phn chiu tia hng ngoi pht ra t lp tip xc P-N.Nguyn l lm vic:Hnh di m t s nguyn l u ni LED hng ngoi trong mch in.S nguyn l ca LED hng ngoiKhi phn cc thun cho it, cc ht dn a s s khuch tn qua tip xc P-N, chng ti hp vi nhau v pht ra bc x hng ngoi. Cc tia hng ngoi bc x ra theo nhiu hng khc nhau. Nhng tia hng ngoi c hng i vo trong cc lp cht bn dn, gp gng phn chiu s c phn x tr li i ra ngoi theo cng hng vi cc tia khc. i ny lm tng hiu sut ca LED.nh sng hng ngoi c c tnh quang hc ging nh nh sng nhn thy, ngha l n c kh nng hi t, phn k qua thu knh, c tiu c.... Tuy nhin, nh sng hng ngoi rt khc nh sng nhn thy kh nng xuyn sut qua vt cht, trong c cht bn dn. iu ny gii thch ti sao LED hng ngoi c hiu sut cao hn LED ch th v tia hng ngoi khng b yu i khi vt qua cc lp bn dn ra ngoi.Tui th ca LED hng ngoi di n 100000 gi. LED hng ngoi khng pht ra nh sng nhn thy nn rt c li trong cc thit b kim sot v khng gy s ch .Cu 3: Trnh by cu to v nguyn l hot ng ca LCD?Cu To:Gm c 2 tm knh t cch nhau khong 10Mm. Mt pha trong ca 2 tm knh trng mt lp oxit km (Zno) trong sut lm hai in cc. Xung quang bn cnh hai tm knh c hn kn, sau tinh th lng vo khong gia 2 tm knh v gn kn li. Hai tm nha c tnh phn cc nh sang c dn bn ngoi hai tm knh sao cho hnh nh phn chiu ca mt ch th c nhn t mt pha nh gng phn chiuNguyn l lm vic:Khi cha c in p t vo, cc thanh LCD khng lm vic, c ngha l khng c in p t ln mt im nh con th phn tinh th lng ti khng b tc ng g c, nh sang sau khi truyn qua ch y vn gi nguyn phng phn cc, v cui cng b chn li hon ton bi knh lc phn cc th hai. im nh con ny b tt v i vi mt ngi quan st th y l mt ddierm ti. Mt ch th trong sut.Khi c in p cung cp thanh LCD n lm thy i s nh hng ca cc phn t tinh th lng ti v kt qu l nh sang sau khi truyn qua phn tinh th lng ch im nh con ny s b xoay phng phn cc i, c th lt qua cc lp knh lc phn cc th hi, to ra mt im mu trn tm knh trcCu 4: Trnh by v cu to v nguyn l hot ng ca it quang dng chuyn tip PN?Cu to:it quang c cu to ging nh cu trc it P-N thong thng, nhng khc l : lp bn dn to ra bi khuch tn gn b mt c chiu dy c 1Mm i vi si v c nng pha tp khng qu cao nh sang cso th xuyn sau v trong long cht bn dn ( xuyn qua chuyn tip PN). Ngoi ra. it quang cn c mt ca s chiu nh sang vo. Hai chan ant A v catt K l kim loi c ni ti cc phn bn dn. it quang lun hot ng ch phn cc ngc.Nguyn l hot ng:it quang c cp ngun Ecc sao cho chuyn tip P N phn cc ngc to ra mt in trng dch chuyn cc ht dn thiu s s c sinh ra di tc dng ca nh sng. Do , khi cha c tc dng nh sng th trong it thu quang ch c dng in ngc (dng in ti hay dng r) rt nh.Khi c chiu sang cc photon ti c hp th trong cc min khc nhau ca it quang (0): cc photon c nng lng cao (tng ng vi bc sng ngn) c hp th trong vng bn dn P+ , cc photon c nng lng thp hn (tng ng vi bc sng di hn) c th tin su ti vng in tch khng gian v vn khuch tn ca khng gian v vng khuch tn ca it. S hnh thnh cc cp in t trong it quang. Di tc dng ca in trng ti vng ny, cc in t v l trng sinh ra trong min in tch khng gian b qut ngay lp tc v min P+ v min N. Cc ht dn ny ng gp vo vic to dng in sinh ra do to cp Jg. Cc cp in t v l trng sinh ra trong vng ha ( vng P+ v vng N) s t khuch tn n bin gii ca min in tch khng gian th chng cng b in trng ny qut i. Cc ht quang ti in khuch tn anfy to thnh dng quang in khuch tn Jndiff v JpdifDo vy, dng quang in ton phn l s hp thnh ca hai dng trn, c tnh ton ti cng mt im trong linh kinJph = Jndiff + J pdiff

Cu 5: Trnh by v cu to v nguyn l hot ng ca it quang PIN?Cu to:it quang loi PIN gm mt lp bn dn N lm nn, trn ph mt lp bn dn nguyn tnh (Intrinsic), ri n lp bn dn loi P+ l in cc vng Ant nh sang c th thm nhp vo min bn dn I. Trn lp bn dn P c ph mt lp mng chng phn x quang trnh tn tht nh sng chiu vo.Nguyn l hot ng:Nguyn l hot ng ca it quang PIN tng t nh nguyn l hot ng ca it quang PN, in p cung cp cho it phn cc ngc theo dng linh kin, v vy lp I b ngho hon ton trong sut thi gian hot ng ca n.Khi cha c chiu sang, trong it ch c dng in ngc rt kh gi l dng in tiKhi c chiu sang cc photon ti c hp th trong cc min khc nhau ca it quang (0): cc photon c nng lng cao (tng ng vi bc sng ngn) c hp th trong vng bn dn P+ , cc photon c nng lng thp hn (tng ng vi bc sng di hn) c th tin su ti vng in tch khng gian v vn khuch tn ca khng gian v vng khuch tn ca it. S hnh thnh cc cp in t trong it quang. Di tc dng ca in trng ti vng ny, cc in t v l trng sinh ra trong min in tch khng gian b qut ngay lp tc v min P+ v min N. Cc ht dn ny ng gp vo vic to dng in sinh ra do to cp Jg. Cc cp in t v l trng sinh ra trong vng ha ( vng P+ v vng N) s t khuch tn n bin gii ca min in tch khng gian th chng cng b in trng ny qut i. Cc ht quang ti in khuch tn anfy to thnh dng quang in khuch tn Jndiff v JpdifDo vy, dng quang in ton phn l s hp thnh ca hai dng trn, c tnh ton ti cng mt im trong linh kinJph = Jndiff + J pdiffCu 6: Trnh by v cu to v nguyn l hot ng ca it quang APD?Cu to:Cu trc gm lp bn dn p, n v lp bn dn yu p-n+ cn gi l min thc, cng in trng trong min ny rt ln, y xy ra qu trnh nhn in t.

p+ i P RL n+

Hnh 1.12: Cu trc ca APD v in trng vng triVng thcTrng ti thiucn thit tcng Ion ha

Nguyn l lm vic ca APD:nh sng i vo thit b xuyn qua vng Pt v c hp th trong vng vt l i, khi c photon b hp th n s truyn nng lng cho in t to ra cc cp in t - l trng v chng b tch di tc ng ca in trng trong vng i. Cc in t ny qua vng i n min p-n+ th chng nhn thm nng lng do in trng mnh ti y. Nng lng thm ny mnh n mc cc in t khi va chm vo cc nguyn t li to ra cc phn t mang in mi gi l Ion ha do va chm, s lng cc phn t mang in tng nhanh, dng in sinh ra c khuch i nhiu ln so vi PIN, do nhy cng tng ln. i vi photodiode Sc, ngng in trng cn thit thu nhn mc 105 V/cm.Cu 7: trnh by cu to v nguyn l hot ng ca transistor quang?Cu to:quang transistor cng ging nh transistor thng nhng cc nn h. Quang transistor c mt thu knh trong sut tp trung nh sng vo ni P-N gia thu v nn.Nguyn l hot ng:Khi cc nn h, ni nn-pht c phn cc thuncht t do cc dng in r (in th VBE lc khong vi chc mV transistor Si) v ni thu-nn c phn cc nghch nn transistor vng tc ngV ni thu-nn c phn cc nghch nn c dng r Ico chy gia cc thu v cc nn. V cc nn b trng, ni nn-pht c phn cc thun cht t nn dng in cc thu l Ico(1+). y l dng ti ca quang transistor. Khi c nh sng chiu vo mi ni thu nn th s xut hin ca cc cp in t v l trng nh trong quang diod lm pht sinh mt dng in I do nh sng nn dng in thu tr thnh: IC=(+1)(Ico+I) Nh vy, trong quang transistor, c dng ti ln dng chiu sng u c nhn ln (+1) ln so vi quang diod nn d dng s dng hn. Hnh trn trnh by c tnh V-I ca quang transistor vi quang thng l mt thng s. Ta thy c tuyn ny ging nh c tuyn ca transistor thng mc theo kiu cc pht chung.C nhiu loi quang transistor nh loi mt transistor dng chuyn mch dng trong cc mch iu khin, mch m loi quang transistor Darlington c nhy rt cao. Ngoi ra ngi ta cn ch to cc quang SCR, quang triacCu 8: Trnh by v cu to v nguyn l hot ng ca t bo quang in:Cu to:T bo quang in l mt bnh cu bng thch anh, trong bnh l chn khng.T bo quang in gm c hai in cc: AntA l mt vng dy kim loi t tm bnh cu. CattK l mt chm cu bng kim loi.Nguyn l hot ng:t mt hiu in th UAKvo hai in cc ca t bo quang in.UAKc th thay i gi tr (m, dng hoc bng 0) ty theo v tr ca con chy C.Chiu nh sng n sc vo catt ca t bo quang in v iu chnh gi tr ca UAKngi ta thu c ng biu din sau y (gi l ng c trng vn - ampe ca t bo quang in)

ng c trng vn - ampe ny (v mt s th nghim c th khc) cho php kt lun: i vi mi kim loi lm catt th cng dng quang in bo ha t l thun vi cng ca chm nh sng kch thch (nh lut quang in th hai) ng nng ban u cc i ca electrn quang in (bng tch e|Uh| ) khng ph thuc vo cng ca chm nh sng kch thch m ch ph thuc vo bc sng ca nh sng kch thch v vo bn cht ca kim loi dng lm catt (nh lut quang in th ba)

CHNG 4: CU KIN C IN TCu 1: Trnh by nguyn l hot ng ca vi cm bin p sutCm bin p sut l g?Cm bin p sutl thit b in tchuyn itn hiu p sut sang tn hiu in, thng c dng o p suthoc dng trong cc ng dng c lin quan n p sut.Nguyn l hot ng cm bin p sutcng gn ging nh cc loi cm bin khc l cn ngun tc ng (ngun p sut, ngun nhit, ngun cn o ca cm bin loi ) tc ng ln cm bin, cm bin a gi tr v vi x l, vi x l tn hiu ri a tn hiu raNguyn l hot ng:Nguyn l lm vic ca cm bin loi ny da trn sbin dngca cu trc mng ( khi c p sut tc ng n) c chuyn thnh tn hiu in nh cy trn cc phn tp in tr.Khi lp mng b bin dng un cong, cc p in tr s thay i gi tr. nhy v tm o ca cm bin ph thuc rt nhiu vomng v kch thc, cu trc, v tr cc p in tr trn mng.

Cu to cm bin kiu p trMng s dng trong cm bin l mng rtnhy vi tc ngca p sut. Bn in tr c t ti 4 trung dim ca cc cnh mng, 2 cp in tr song song vi mng v 2 cp in tr vung gc vi mng ( khi mng b bin i th 2 cp in tr ny c chiu bin dng tri ngc nhau ). Bn in tr trn c ghp li to thnhcu Wheatsone.

Cm bin p sut kiu p trKhi khng c p sut tc ng cc in tr trng thicn bng, in p ng ra bng0. Khi c p sut tc ng mng mng b bin dng , cc gi tr in tr thay i, c th gi tr cc p in tr song song vi cnh mng gim th gi tr cc p in tr vung gc vi cnh mng tng v ngc li khi s to in p ng ra khc 0. S thay i gi tr in tr ph thuc v bin dng ca mng, v vy bng cch kim tra in p ng ra ta c th tnh ton c psut cn o.

Cu 2: Trnh by nguyn l hot ng ca vi cm bin gia tcNguyn l hot ng:Hiu ng p in tr l hin tng thay i in tr ca vt liu tinh th di tc dng ca ng sut c. Nguyn nhn l c tnh d hng ca phn gii mc nng lng trong khng gian tinh th. Ngi ta ng dng hiu ng ny trong vic ch to cm bin da trn bin dng c l mng mng hoc cu trc thanh dm. Trong cc cm bin gia tc p in tr th dch chuyn ca khi gia trng s lm thanh dm bin dng v cc in tr c cy trn cc thanh dm s bin i t l thun vi gia tc tc dng ln khi gia trng. Vic cy tp cht nng cao s to ra p in tr trn cu trc thanh dm treo vt nng. Yu cu kht khe i vi cc cm bin nhiu bc t do (trong bi bo ny l ba bc t do) l tuyn tnh ln v nh hng gia cc mode hot ng (ngi ta cn gi l nhy php tuyn) phi nh. Tt nhin l cm bin phi p ng c yu cu v nhy cao theo 3 hng tnh tin. Bi bo ny xut mt cu trc c kch thc rt nh l 1.51.50.5 mm3bao gm mt khi gia trng c treo bi h thng 4 thanh dm ch chi. Cm bin p in tr 3 chiu nhn t trn xung Khi cm bin chu tc dng ca gia tc tnh tin theo phng Z (hnh 2.a) th khi gia trng schuyn ng ln hoc xung. Khi cm bin chu tc dng ca gia tc tnh tin theo phng ngang th khi gia trng b lch theo X hoc Y. lch ca thanh dm khi chu gia tc tc dng s gy nn ng sut tuyn tnh. S thay i in tr s c bin i thnh tn hiu in nh s dng mch in x l bn ngoi l cc mch cu Wheaston. Trong thit k ny, 12 p in tr c cy trn 4 thanh dm.Cu 3: Trnh by nguyn l hot ng ca vi cm bin sinh hcNguyn l hot ng:Nguyn l hot ng ca cm bin s dng chuyn i ny nh sau: chiu mt chm laser n b phn x trn b mt mt thanh dm rt mng, nh sng phn x c thu nhn bi photodetector. Thanh mng ny c ch to sao cho ch vi mt lc tc ng rt nh cng lm cho thanh b un cong i. Nh vy tn hiu phn x thu nhn c trn photodetector s b thay i so vi trng hp khng c lc tc dng ln thanh. Cn c vo s thay i tn hiu phn x ny, ngi ta c th xc nh c lc tc dng ln thanh

Cu 4: Trnh by nguyn l hot ng ca vi chuyn mchNguyn l hot ng:C cu to chuyn ng cho bn cc trong vi c in t thng c gi l cc b vi chp hnh (microactuator). Cc vi chp hnh vi c in t thng c thit k da trn nguyn l: nhit in, t in, v p in. Chuyn mch RF MEMS c thi gian hot ng lu nht cng nh tin cy cao nht c ch to cho n nay c cu trc kch hot da trn cu to kiu t in. Cng sut tiu th ca vi chuyn mch ny ti trng thi ng hoc m gn nh bng khng.C hai loi mch tip gip ph bin trong chuyn mch l ng m kiu Ohmic hay kiu t in. Cc chuyn mch Ohmic vi c in t s dng nguyn l ng m l kim loi do n c th dng c cho cc h thng vi tn hiu t dc n RF (xem hnh 4.15). Chuyn mch kiu t in thay i v tr ca mt trong hai bn cc t in t trng thi ng sang m hoc ngc li (xem hnh 4.16). Khi , gi tr ca in dung t in gia hai bn cc cng thay i theo. Cu trc kiu t in ny, do , ch c dng trong cc h thng RF m khng th dng trong cc mch dc.Chuyn mch vi c in t MEMS c thit k v ch to tng thch vi quy trnh ch to CMOS. Hin nay, hu ht cc chuyn mch vi c in t MEMS c ch to trn cng mt silic chung vi cc chip in t v do n c th thay th cho cc chuyn mch truyn thng c s dng nhiu trong chip da trn linh kin bn dn nh diode v transistor trng. Hu ht cc chuyn mch knh trong in thoi di ng hin nay u s dng cc chuyn mch vi c in t do n cho phm cht cao, nng lng tiu th thp v thi gian s di so vi cc chuyn mch truyn thngChng 5Bi tp 1:c ng dng sm nht l cng ngh cm ng in tr, y l cng ngh iu khin nhy cm vi p lc tc ng ln b mt. Cu to ca cng ngh cm ng in tr ny gm hai lp mng: lp cht dn in v lp in tr. Hai lp ny c ph mt hp cht gi l ITO v c cch nhau mt khong trng m mt thng kh c th nhn bit. Trong qu trnh hot ng, cc dng in vi mc in th khc nhau s c truyn qua hai lp ny. Khi tc ng ln mn hnh, hai lp tng tc ny chm nhau v mch in s c ni. Lp pha trn s ly in th t lp di v lp di s ly in th t lp trn, do vy, b iu khin s xc nh c ta v tr tip xc. Do cu to c trng l cn khong h gia hai lp tng tc nn cng ngh cm ng in tr rt km v truyn dn, s hn ch nh sng pht ra t mn hnh bn di. V vy, m bo kh nng hin th cng nh bn ca mn hnh, nh sn xut thng ch c gii php t mt tm bo v trong sut (thng l arcrylic) rt mng gia lp cm ng v mn hnh.Trong khi , c th nhn bit tc ng ca ngi dng, yu cu tin quyt ca cng ngh mn hnh cm ng in tr l phi c lp tng tc pha trn mm, c th bin dng khi c lc tc ng v khng th bo v bng nhng lp cng trong sut. V vy, nhiu ngi dng cm thy bt an khi thao tc trn mn hnh ny, bi khi tc ng, h cm thy mn hnh c v qu mm, s rng thao tc mnh c th khin mn hnh bn di hng.

Hnh 5. 2 Mn hnh cm ng kiu in trMt khc, c tnh mm, li khng c bo v nn lp ny thng rt d try cng nh d b bin dng nu tc dng lc qu ln, khin mch b chm, gy ra hin tng km nhy hoc lit cm ng thng gp.Bi tp 2:

Cu to v nguyn l hot ng.Thit b cm ng in dung c to nn t mt hay nhiu nt cm bin in dung, cc nt cm ng in dung thng c sp xp trn mt ma trn hai chiu XY. Mt cc nt cm bin trn mt din tch b mt ca thit b cm ng in dung to nn phn gii cm ng ca thit b ny. Khi c mt s tc ng t bn ngoi ti mt nt cm ng trn ln mng li cc nt, v d nh tay ngi chm vo b mt nt cm ng, s lm cho in dung ca nt cm ng thay i trc tip hoc gin tip theo s tc ng . Cc thay i in dung trc tip do cc tc ng lm thay i cu trc vt l ca nt cm ng gy ra, v d nh tc ng lm thay i khong cch gia hai bn cc, cc tc ng lm x dch v tr cc bn cc, cc tc ng lm thay i cht in mi gia hai bn cc, in dung ca nt cm ng c th b thay i gian tip thng qua cc tc ng lm thay i trng in t sinh ra khi nt cm ng hot ng. Cu to ca mt nt cm ng in dung bao gm nhiu thnh phn khc nhau, ty vo tng cng ngh c s dng (mn hnh cm ng hay chut cm ng, ), nhng v c bn n gm c 4 b phn chnh l: 2 bn cc kim loi, cht in mi v lp ph b mt. 0 l mt v d cho thy cu to ca mt bng cm ng in dung.

Hnh 5. 3 Mt ct ngang ca mt bng cm ng in dungLp Overlay l mt lp ph b mt va c tc dng bo v b phn cm bin bn di, va c tc dng nh mt cht in mi ca t in hnh thnh khi tay ngi hoc mt cht dn in no chm vo b mt ca nt cm bin. Trong cc thit b iu khin c h tr tng tc v mt hnh nh nh mn hnh in thoi th lp Overlay c lm trong sut c th quan st c hnh nh bn di bng cm ng.

Hnh 5. 4 Nt cm bin in dung khi khng c tc ng t bn ngoiNt cm bin in dung c hai bn cc kim loi, nh hai bn cc ca mt t in, cht liu thng c s dng ch to l: ng, Indium tin oxide (ITO) hay mc in. Nt cm ng in dung c lm t ng c th thc hin trn mt bng mch in PCB theo tiu chun FR4, chut cm ng ca my tnh thng c thit k theo cch ny. Cht liu ITO l mt hp cht oxit thic, n cho php to ra cc b cm bin vi trong sut ln ti 90%, cht liu ny thch hp cho cc ch to mn hnh cm ng in dung. bit c s hot ng c bn ca mt nt cm ng in dung cng nh ca mt thit b cm ng in dung, ta xem xt thay i ca n trc v sau khi c s tc ng ca tay ngi ti b mt cm bin.Khi khng c tc ng ca ngn tay hay bt k mt cht dn in no khc, th trn cm bin in dung c in dung l CP , in dung ny gi l in dung k sinh ca b cm bin. Khi mt ngn tay chm vo b mt cm ng, mt t in mi c hnh thnh, t in ny song song vi t in k sinh, theo lm tng in dung ca b cm bin.

Hnh 5. 5 S thay i in dung khi c tc ng t bn ngoi

Hnh 5. 6 S thay i in dung khi c tc ng t bn ngoiS thay i in dung ca nt cm bin c chuyn sang dng tn hiu s phc v vic pht hin tip xc. Phng php in hnh thc hin vic ny l xc nh in p trn t, do in dung ca t t l vi in p trn n theo cng thc (4.1) nn s thay i in dung cng dn ti s thay i ca in p ti hai bn cc ca b cm bin.

(5.1)Vi cc thit b cm ng in dung c nhiu nt cm bin, th cn phi c mt b ghp knh c th o tn hiu cm ng t nhiu lung khc nhau.

Hnh 5. 7 Xc nh s thay i ti nhiu nt cm bin0 th hin phng php o tn hiu cm ng trn mt ma trn nt cm ng, trong , ngun tn hiu (Signal Source) to ra tn hiu kch thch cho b cm bin hot ng trn cc ng Drive lines, sau cc tn hiu cm ng (Sense lines) s c a ti mt b ghp knh v a ti b chuyn i tng t sang s A/D converter chuyn i sang dng tn hiu s. Mch DSP s s l c bn tn hiu s v truyn ti mt my tnh ch phc v cc lnh iu khin.Bi tp 3:Mn hnh cm ng hng ngoi (infrared touchscreen):C phn ging mn hnh cm ng in tr, mn hnh cm ng hng ngoi pht ra cc tia hng ngoi theo chiu ngang v dc trn b mt mn hnh to ra mt li nh sng. Nguyn l hot ng da trn cng ngh ngt tia sng. V c bn, mn hnh cm ng hng ngoi b tr u pht tia hng ngoi mt (hay hai) cnh mn hnh, i din vi u pht l cm bin nh sng hay b d nh sng.

Hnh 5. 8Cu to ca mn hnh cm ng hng ngoiKhi mn hnh c tc ng, v tr bt trm hay bt k vt th no "cn" ng truyn ca tia hng ngoi, tn hiu nhn c u b thu hay cm bin nh sng s b gin on. Ngay lp tc, b d hay cm bin nh sng s tm c ta ca im tip xc trn mn hnh.Bi v phng php ny khng s dng cc lp tng tc trn b mt mn hnh nn khng cn tr bt k ngun sng no t mn hnh hin th bn di, gip hnh nh nhn thy thc v sng r. Ngoi ra, mn hnh cm ng hng ngoi cng c th c ph thm mt lp knh trong v cng tng tnh an ton.Mn hnh cm ng hng ngoi thng c dng trong cc ki-t thng tin cng cng, mn hnh trong lnh vc y t, sn xut cng nghip, my bn hng t ng v nhng ni c iu kin mi trng khc nghit.Mn hnh cm ng sng m thanh b mt (Surface acoustic wave SAW - touchscreen): L dng mn hnh cm ng tin tin nht. Cng ngh SAW da trn hai b thu/pht sng m thanh (transducer) trn ng thi trc X v trc Y ca mn hnh cm ng. Mt thnh phn quan trng khc ca SAW c t trn mt knh mn hnh, c gi l b phn hi (reflector). Nguyn l hot ng ca mn hnh cm ng sng m cng tng t mn hnh cm ng hng ngoi, l kim sot s ngt qung tn hiu, trong trng hp ny l sng siu m.B iu khin ca mn hnh cm ng s gi tn hiu in t sang b pht sng, v b pht sng s chuyn i tn hiu nhn c sang dng sng siu m chuyn tip sng m ny n b phn hi c t u bn kia panel mn hnh. Sau khi b phn hi "khc x" tn hiu li cho b thu sng, tn hiu s c b thu gi tr cho b iu khin. Khi mt ngn tay hay bt trm chm vo mn hnh, chm sng ang di chuyn ngang/dc trn mn hnh s b ngt qung v to ra mt "bin c chm" t b iu khin xc nh chnh xc v tr im tip xc.Do s dng panel knh - khng phi cc lp tng tc c th b hao mn nh mn hnh cm ng in tr hay in dung - cng ngh SAW cung cp nhng thuc tnh quan trng nh bn cho b mt cm bin, trong sut v phn gii cao cho hnh nh hin th. im tr cho mn hnh cm ng s dng cng ngh SAW l phi "chm" bng ngn tay, bn tay c eo gng v bt trm loi mm (vt dng cng nh u vit bi khng th s dng c), v c bit mn hnh cm ng dng ny khng th c "bt kn" tuyt i nn c th d b tc ng bi bi, bn hay nc trong mi trng xung quanh.Cng ngh SAW c khuyn khch s dng trong cc my ATM, cng vin, bo tng, cc ng dng ti chnh v ngn hng, ki-t thng tin cng cng, h thng hun luyn da trn my tnh.