Chapter 10 Diodes. 1. Understand diode operation and select diodes for various applications.

Transcription

1 Chapter 10 des 1. Understand dde peratn and select ddes fr arus applcatns. 2. nalyze nnlnear crcuts usng the graphcal lad-lne technque. 3. nalyze and desgn smple ltage-regulatr crcuts. 4. Sle crcuts usng the deal-dde mdel and pecewse-lnear mdels. 5. Understand arus rectfer and wae-shapng crcuts. 6. Understand small-sgnal equalent crcuts.

2 10. des Basc de Cncepts 10.1 Basc de Cncepts Intrnsc Semcnductrs * Energy agrams Insulatr, Semcnductr, and Cnductr the energy dagram fr the three types f slds 2

3 10. des Basc de Cncepts Intrnsc Semcnductrs * Intrnsc (pure) S Semcnductr: Thermal Exctatn, Electrn-Hle Par, ecmbnatn, and Equlbrum When equlbru m between exctatnandrecmbnatn sreached: electrndensty hledensty n p frntrnscscrystalat300k ( Nte: Scrystal atm densty 10 s~ cm -3 cm -3 ) 3

4 10. des Basc de Cncepts Intrnsc Semcnductrs *pply a ltage acrss a pece f S: electrn current and hle current 4

5 10. des Basc de Cncepts N- and P- Type Semcnductrs * png: addng f mpurtes (.e., dpants) t the ntrnsc semcnductr materal. * N-type: addng Grup V dpant (r dnr) such as s, P, Sb, n p Fr n In n n p n-typemateral N N S d d We call cnstant n at 2 the >> 300K n p electrn the majr hle the mnr, p fr a semcnductr ( ) dnr cnceratn 2 << p charge carrer cahage carrer 2 5

6 10. des Basc de Cncepts N- and P- Type Semcnductrs * png: addng f mpurtes (.e., dpants) t the ntrnsc semcnductr materal. * P-type: addng Grup III dpant (r acceptr) such as l, B, Ga, n n In p p We p Fr p hle S p- N N call the electrn type a a cnstant n at 2 the >> majr the 300K materal acceptr p p 2, n fr mnr a 10 ( ) << n charge semcndu ctr cncerat n cahage 2 carrer carrer 6

7 10. des Basc de Cncepts The PN-Junctn * The nterface n-between p-type and n-type materal s called a pn-junctn. The barrerptentalv V frs and 0.3V frge at300k: ast,v B. B 7

8 10. des Basc de Cncepts Basng the PN-Junctn * There s n mement f charge thrugh a pn-junctn at equlbrum. * The pn-junctn frm a dde whch allws current n nly ne drectn and preent the current n the ther drectn as determned by the bas. 8

9 10. des Basc de Cncepts Basng the PN-Junctn *Frward Bas: dc ltage pste termnal cnnected t the p regn and negate t the n regn. It s the cndtn that permts current thrugh the pn-junctn f a dde. 9

10 Basng the PN-Junctn *Frward Bas: dc ltage pste termnal cnnected t the p regn and negate t the n regn. It s the cndtn that permts current thrugh the pn-junctn f a dde. 10

11 10. des Basc de Cncepts Basng the PN-Junctn *Frward Bas: 11

12 10. des Basc de Cncepts *eerse Bas: dc ltage negate termnal cnnected t the p regn and pste t the n regn. epletn regn wdens untl ts ptental dfference equals the bas ltage, majrtycarrer current ceases. 12

13 10. des Basc de Cncepts *eerse Bas: majrty-carrer current ceases. * Hweer, there s stll a ery small current prduced by mnrty carrers. 13

14 10. des Basc de Cncepts Basng the PN-Junctn * eerse Breakdwn: s reerse ltage reach certan alue, aalanche ccurs and generates large current. 14

15 10. des Basc de Cncepts The de Characterstc I-V Cure 15

16 V 10. des Basc de Cncepts Shckley Equatn * The Shckley equatn s a theretcal result under certan smplfcatn: where current, T ksthebltzman' when Ths I s kt exp nv I q s n 10 equatn -14 1t 0.026V 0.1V, s T 1 at 2s nt at 300K the 300K scnstant, s the(reerse) emssn sthe q thermal Isexp nv T applcable when ceffcen t, < saturat n ltage C 16

17 10. des Lad-Lne nalyss f de Crcuts 10.2 Lad-Lne nalyss f de Crcut We but It s can use when theresadde: dffcult, t wrte C d dt KCL, r L d dt,... Is exp nv T KVLequatns. 1 Fr the crcutshwn, KVL ges: VSS + IftheI-V cure f theddesgen, wecan perfrm the " Lad-Lnenalyss" 17

18 10. des Lad-Lne nalyss f de Crcuts Example Lad-Lne nalyss Fr the crcutshwn, Gen:VSS 2V, 1kΩ, thei-v cure f the dde Fnd: the dde currentandltage atthe peratng pnt(q-pnt) V SS 2 perfrm lad- lne analyss at the peratng pnt V 1000 Q V,,.e., Q 1.3m 18

19 10. des Lad-Lne nalyss f de Crcuts Example Lad-Lne nalyss Fr the crcutshwn, Gen:Vss 10V, 10kΩ, thei-vcuref the dde Fnd: the dde currentandltage atthe peratngpnt V SS 10 10k perfrm lad- lne analyss at the peratng pnt V Q V,,.e., Q 0.93 m 19

20 10. des Zener de Vltage-egulatr Crcuts 10.3 Zener-de Vltage-egulatr Crcuts The Zener de * Zener dde s desgned fr peratn n the reerse-breakdwn regn. * The breakdwn ltage s cntrlled by the dpng leel (-1.8 V t -200 V). * The majr applcatn f Zener dde s t prde an utput reference that s stable despte changes n nput ltage pwer supples, ltmeter, 20

21 10. des Zener-de Vltage-egulatr Crcuts Zener-de Vltage-egulatr Crcuts * Smetmes, a crcut that prduces cnstant utput ltage whle peratng frm a arable supply ltage s needed. Such crcuts are called ltage regulatr. * The Zener dde has a breakdwn ltage equal t the desred utput ltage. * The resstr lmts the dde current t a safe alue s that Zener dde des nt erheat. 21

22 10. des Zener-de Vltage-egulatr Crcuts Example 10.3 Zener-de Vltage- egulatr Crcuts Gen:the Zener Fnd :theutput dde I ltage -V frv cure, V SS SS 1kΩ 15V 20V and KVLgestheladlne: V SS V Frm theq-pntwehae 10.0V fr 0 V frv 0.5V changen SS SS 5V changennput 15V 20V : ctual Zener dde perfrms much better! 22

23 10. des Zener-de Vltage-egulatr Crcuts Lad-Lne nalyss f Cmplex Crcuts * Use the Theenn Equalent 23

24 10. des Zener-de Vltage-egulatr Crcuts Example 10.4 Zener-de Vltage-egulatr wth a Lad Gen:Zener dde I-Vcure, Fnd:thelad V I ltage L V T V (V - )/ m SS 24V, 1.2kΩ, 6kΩ and surce currentsi pplyng Theenn Equalent V T L S SS L T V SS S L + L L 20V, T L + L 1kΩ 24

25 10. des Zener-de Vltage-egulatr Crcuts Quz Exercse 10.5 Gen: the crcutand the ZenerddeI-V cure asshwn. Fnd:theutput ltage frl 0,L 20m,andL 100m 25

26 10. des Ideal-de Mdel 10.4 Ideal-de Mdel * Graphcal lad-lne analyss s t cumbersme fr cmplex crcuts, * We may apply Ideal-de Mdel t smplfy the analyss: (1) n frward drectn: shrt-crcut assumptn, zer ltage drp; (2) n reerse drectn: pen-crcut assumptn. * The deal-dde mdel can be used when the frward ltage drp and reerse currents are neglgble. 26

27 10. des Ideal-de Mdel 10.4 Ideal-de Mdel * In analyss f a crcut cntanng ddes, we may nt knw n adance whch ddes are n and whch are ff. * What we d s frst t make a guess n the state f the ddes n the crcut: (1)Fr (2) LL nt " Fr" assumed assumed YES LL YES BINGO! n ff ddes" make ddes" terates :check anther untl : check " f f guess... s LL YES" s pste; negate 27

28 10. des Ideal-de Mdel Example 10.5 nalyss by ssumed de States nalyss thecrcut by assumng s 1 ff and 2 n (1) assume ff, 1 2 n (2) assume 1 n, 2 ff m OK! 7V ntok! 1 2 1m -3V OK! OK! 28

29 10. des Ideal-de Mdel Quz Exercse 10.8c * Fnd the dde states by usng deal-dde mdel. Startng by assumng bth ddes are n. (1) assume 3 n n 4 (2) assume 3ff and 4 n m, ntok 6.7m, OK 4 3 5m, -5V, OK OK 29

30 10. des Pecewse-Lnear de Mdels 10.5 Pecewse-Lnear de Mdels Mdfed Ideal-de Mdel * Ths mdfed deal-dde mdel s usually accurate enugh n mst f the crcut analyss. 30

31 10. des Pecewse-Lnear de Mdels Pecewse-Lnear de Mdels + a V a 31

32 10. des ectfer Crcuts 10.6 ectfer Crcuts * ectfers cnert ac pwer t dc pwer. * ectfers frm the bass fr electrnc pwer supplers and battery chargng crcuts Half-Wae ectfer 32

33 10. des ectfer Crcuts * Battery-Chargng Crcut * The current flws nly n the drectn that charges the battery. 33

34 10. des ectfer Crcuts * Half-Wae ectfer wth Smthng Capactr * T place a large capactance acrss the utput termnals: 34

35 10. des ectfer Crcuts Full-Wae ectfer Crcuts * Center-Tapped Full-Wae ectfer tw half-wae rectfer wth ut-fphase surce ltages and a cmmn grund. * When upper surce supples + ltage t dde, the lwer surce supples - ltage t dde B; and ce ersa. * We can als smth the utput by usng a large capactance. 35

36 10. des ectfer Crcuts Full-Wae ectfer Crcuts * The de-brdge Full-Wae ectfer:,b C, 36

37 10. des Wae-Shapng Crcuts 10.7 Wae-Shapng Crcuts Clpper Crcuts * prtn f an nput sgnal waefrm s clpped ff. 37

38 10. des Wae-Shapng Crcuts 10.7 Wae-Shapng Crcuts Clamper Crcuts * Clamp crcuts are used t add a dc cmpnent t an ac nput waefrm s that the pste (r negate) peaks are clamped t a specfed ltage alue. 38

39 10. des Lnear Small-Sgnal Equalent Crcuts 10.8 Lnear Small-Sgnal Equalent Crcuts * In mst f the electrnc crcuts, dc supply ltages are used t bas a nnlnear dece at an peratng pnt and a small sgnal s njected nt the crcuts. * We ften splt the analyss f such crcut nt tw parts: (1) nalyze the dc crcut t fnd peratng pnt, (2) nalyze the small sgnal ( by usng the lnear smallsgnal equalent crcut.) 39

40 10. des Lnear Small-Sgnal Equalent Crcuts 10.8 Lnear Small-Sgnal Equalent Crcuts * dde n lnear small-sgnal equalent crcut s smplfed t a resstr. * We frst determne the peratng pnt (r the quescent pnt r Q pnt) by dc bas. * When small ac sgnal njects, t swngs the Q pnt slghtly up and dwn. * If the sgnal s small enugh, the characterstc s straght. d d s s the the Q small small change n dde current change n dde ltage d d Q 40

41 des Lnear Small-Sgnal Equalent Crcuts 10.8 Lnear Small-Sgnal Equalent Crcuts Q d d Q T d d d d d d d Q 1 Q d I nv r : hae we equatn, Shckley the by applyng e, Furthermr r : sgnals ac fr hae we changes, small dentng and by and eplace r d d : hae wll We d d r : as dde the f resstance dynamc the efne

42 10. des Lnear Small-Sgnal Equalent Crcuts 10.8 Lnear Small-Sgnal Equalent Crcuts d d, rd rd nv I T Q * By usng these tw equatns, we can treat dde smply as a lnear resstr n small ac sgnal analyss. * Nte: n ac ltage f fxed ampltude prduces dfferent ac current change at dfferent Q pnt. 42

43 10. des Lnear Small-Sgnal Equalent Crcuts 10.8 Lnear Small-Sgnal Equalent Crcuts I Q + d V Q + d d d, rd rd nv I T Q (1)V (2) (3) Q and atthe Q pnt. d and and d I Q represent the dc sgnals represent the small sc sgnals. represent the ttal nstantane us dde ltage andcurrent. 43

44 10. des Lnear Small-Sgnal Equalent Crcuts Vltage-Cntrlled ttenuatr * The functn f ths crcut s t prduce an utput sgnal that s a arable fractn f the ac nput sgnal. * Tw large cuplng capactrs: behae lke shrt crcut fr ac sgnal and pen crcut fr dc, thus the Q pnt f the dde s unaffected by the ac nput and the lad. Z C 1 jωc 44

45 10. des Lnear Small-Sgnal Equalent Crcuts Vltage-Cntrlled ttenuatr Frst apply dcanalysst fndtheddeq pnt, determne I Q, then the r d f thedde 1 p p, based n ltage dder: < r + :r Next, we perfrm small ac sgnal analyss: (nte: the dc ltage surce has an ac cmpnentf currentbut n ac ltage, the dc ltage surce sequalenttashrtcrcut fracsgnal.) C L d d nv I T Q n p 1 45

46 10. des Lnear Small-Sgnal Equalent Crcuts Exercse Vltage-Cntrlled ttenuatr Gen: Fnd : the Q- pntalues assumng V and 100Ω, frv 1.6and10.6V Frst apply dc analysst fndthe dde Q pnt, VC -0.6 nvt IQ, rd wthv C IQ Next, we perfrm small ac sgnal p 1 C L C C + 1 r d L, 2kΩ, dde n 1at T n f 0.6V 0.026V analyss: + p p 300K 46

47 Chapter 11: mplfers: Specfcatns and External Characterstcs

48 11. mplfers Basc mplfer Cncepts 11.1 Basc mplfer Cncepts Fr Startng * Ideally, an amplfer prduces an utput sgnal wth dentcal waeshape as the nput sgnal but wth a larger ampltude. ( t) ( t) s the Vltage Gan 48

49 11. mplfers Basc mplfer Cncepts Fr Startng * nertng and nn-nertng amplfers 49

50 11. mplfers Basc mplfer Cncepts Fr Startng * Often, ne f the amplfer nput termnals and ne f the utput termnals are cnnected t a cmmn grund. * The cmmn grund sere as the return path fr sgnal and the dc pwer supply currents. 50

51 11. mplfers Basc mplfer Cncepts Fr Startng * nther example fr cmmn grund 51

52 11. mplfers Basc mplfer Cncepts Vltage-mplfer Mdel * mplfcatn can be mdeled by a cntrlled surce. mplfer : the nput resstance(rmpedance), s the equalent when lkng nt the nputtermnals. : nsereswth the utputtermnals, s the utputresstance(rmpedance) c / : the pen-crcutltage gan (nte: the real gan ssmaller tham ) resstance seen 52

53 11. mplfers Basc mplfer Cncepts Current and Vltage Gans s the currentdelered nt the nputtermnals f the amplfer; s the current flwng thrugh the lad. The currentgan Furthermre, s the rat between utputandnputcurrents: L L, where s the ltage gan The ltage gan s thanthe penusually smaller crcut ltage gan 53

54 11. mplfers Basc mplfer Cncepts Pwer Gan The pwer gan sthe ratf the utput pwertthe nput Snce the aerage pwersthe prductf the rms we hae: G P P V V rms rms I I rms rms ( ) 2 L aluesv rms pwer:g and I, rms P P 54

55 11. mplfers Basc mplfer Cncepts Example 11.1 Calculatng mplfer Perfrmance Fnd the ltage gans s V/Vsand V/V ls, fnd the currentgan andthe pwergan s V V V V s V V ( /( + )) (( + )/ ) L V V s ( Nte: due t the ladng effect, < < ) L s + s + L L 5333, L , G

56 mplfers Cascade mplfers 11.2 Cascade mplfers c GG G, In addtn,

57 11. mplfers Cascade mplfers Example 11.2 Calculatng Perfrmance f Cascade mplfer 2 L1 Fnd the current gan, ltage gan, and pwer gan G G G G , , 7 2, G L L + L

58 11. mplfers Cascade mplfers Example 11.3 Smplfed Mdel fr mplfer Cascade

59 11. mplfers Pwer Supples and Effcency Pwer Supples and Effcency * The pwer gan f an amplfer s usually large, the addtnal pwer s taken frm the pwer supply. The ttal aerage pwer suppled t the amplfers P Cnseratn f energy: P P P P s d nternalcarcuts The effcency f an amplfer: η V + P sthe pwerf nputsgnal sthe pwerf utputsgnal sthe pwer dsspated n P P s s I P + V + 100% P BB d I B 59

60 mplfers Pwer Supples and Effcency Example 11.4 mplfer Effcency 35.6% P P η 14.5W P P P P 22.5W I V I V P 8W V P 8Vrms V V pw 10 W 10 V P s s d B BB s L 2 L L

61 11. mplfers ddtnal mplfer Mdels 11.4 ddtnal mplfer Mdels Current-mplfer Mdel Theenn s. Nrtn apprach and sc the shrt crcut current gan sc and sc are the same fr the tw mdels. : 61

62 11. mplfers ddtnal mplfer Mdels Example 11.5 Transfrm Vltage-mplfer t Current-mplfer Mdel sc sc and sc

63 11. mplfers ddtnal mplfer Mdels 11.4 ddtnal mplfer Mdels Transcnductance-mplfer Mdel G msc sc Transresstance-mplfer Mdel msc sc 63

64 11. mplfers Ideal mplfers 11.6 Ideal mplfers Vltage mplfer :, 0, max. max Maxmum Vltage Gan! s Currentmplfer : 0,, sc sc max. max. Maxmum CurrentGan! 64

65 11. mplfers Frequency espnse 11.7 Frequency espnse * The gan f an amplfer s a functn f frequency. * Bth ampltude and phase are affected. V V Example 11.8 The nput fra certanamplfer s: the utpt s ( t) 0.1 cs( 2000πt 30 ) ( t) 10cs( 2000πt+ 15 ) Fnd the cmplex ltage gan and expressthe ampltude ndb : 0 V , V Nte: there sa phase shft. V V db 20lg 20 lg( 100 ) 40dB 65

66 11. mplfers Frequency espnse Gan as a Functn f Frequency 66

67 11. mplfers Frequency espnse C Cupled mplfers The gan drps t zer at dc (lw frequency). 67

68 11. mplfers Frequency espnse C Cupled mplfers mplfers that are realzed as ntegrated crcuts are ften dc cupled, because capactrs r transfrmers can nt be fabrcated n ntegrated frm. 68

69 11. mplfers Frequency espnse Hgh-Frequency rp Off * The small amunt f capactance n parallel r nductances n seres wth the sgnal path n the amplfer crcut wll cause the gan f the amplfer t drp at hgh frequences. j2πfl, pen as f 1/j2 πfc, shrt as f 69

70 11. mplfers Frequency espnse Half-Pwer Frequences and Bandwdth * Bandwdth s the dstance between the half-pwer frequences. * Half-pwer frequences: md 20lg(1/ / 2 3dB 2) db frm md * Wdeband (Baseband) mp. * Narrwband (Bandpass) mp. 70

71 11. mplfers Lnear Waefrm strtn 11.8 Lnear Waefrm strtn * strtn may ccur een thugh the amplfer s lnear (.e., beys superpstn prncple). mpltude strtn If a sgnal cntans cmpnents f arus frequences, the utput waefrm may be dstrted due t the frequency respnse f the amplfer gan. 71

72 11. mplfers Lnear Waefrm strtn Phase strtn * If the phase shft f an amplfer s nt prprtnal t the frequency, phase dstrtn may ccur. ssume we hae annputlke: ( t) 3cs( 2000π t) cs( 6000π t) and three amplfers hang the gans : The utput B C wuld lk lke : ( t) 30cs( 2000π t) 10cs( 6000π t) ( t) 30cs( 2000π t 45 ) 10cs( 6000π t 135 ) ( t) 30cs( 2000π t 45 ) 10cs( 6000π t 45 ) 72

73 11. mplfers Lnear Waefrm strtn 11.8 Lnear Waefrm strtn * In rder t ad dstrtn: (1) the magntude f the gan must be cnstant aganst frequency. (2) The phase respnse must be prprtnal t the frequency. θ 1 Δt : θ 1 : 2 Δt ω 2 : ω θ1 T 2π θ1 T 2π 1: 1 T The same tme delay! :T 1 θ2 : T2 2π θ1(ω1/ : 2π ω 2 ) T 1 (ω 2 / ω 1 ) 73

74 11. mplfers Pulse espnse 11.9 Pulse espnse 74

75 11. mplfers Nnlnear strtn Nnlnear strtn 75

76 11. mplfers fferental mplfers fferental mplfers * fferental amplfer has tw nput surces, the utput ltage s prprtnal t the dfference between the tw nput ltages. ( t) d[ 1( t) 2( t) ] ( t) ( t) d 1 Nn-nertng nput 2 Inertng nput d efne d and d We can 1 a dfferenta d the dfferent wrte d 2 the dfferenta l al l the utput amplfer sgnal gan f as : : 76

77 11. mplfers fferental mplfers Electrcardgram * The desred waefrm s gen by the dfference between the ptentals measured by the tw electrdes,.e., the utput f an deal dfferental amplfer. ( - ) d d * Whle bth electrdes (als act lke antennas) pck a cmmnmde sgnal (nse) frm the 60 Hz pwer lne: 1 + Vncs(377t + φn), 2 + Vncs(377t + φ n d )

78 11. mplfers fferental mplfers Electrcardgram dd V + V n n cs(377t cs(377t d ( φ φ n n - ), ) 2 ) * Ideally, the cmmn-mde sgnal was nullfed by the dfferental amplfer. * Hweer, real dfferental amplfer respnds t bth dfferental-mde and cmmn-mde sgnals: where s the cmmn -mde gan, d d + d cm cm s the dfferent al- mde sgnal and cm cm the cmmn - mde sgnal Cmmn-Mde ejectn at (CM): CM 20lg d cm * t 60 Hz, CM f 120 db s cnsdered gd. 78

79 11. mplfers fferental mplfers Example etermnatn f Mnmum CM Specfcatn * Fnd the mnmum CM fr an electrcardgram amplfer f the dfferental gan s 1000, the desred dfferental nput sgnal has a peak ampltude f 1 mv, the cmmn-mde sgnal s 100 V-peak 60 Hz sne wae, and t s desred that utput cntan a peak cmmn-mde sgnal that s 1% r less f the peak utput caused by the dfferental sgnal. peak d 1mV, d 1000 d 1V peak cm < 1V 1% 0.01V cm < 0.01V 100V 10 4 CM 20lg d cm > 20lg dB ns : CM > 140 db 79