Modelos del Diodo

nodoCtodo(a) Smbolo del circuitoRegin de ruptura inversaRegin de polarizacin inversaRegin de polarizacin directa(b) Curva caracterstica tensin-corrienteMODELO REAL DEL DIODO

MODELO REAL DEL DIODOVT, es el potencial trmico del diodo y es funcin de la constante de Boltzmann (K), la carga del electrn (q) y la temperatura absoluta del diodo T(K).

Curva caracterstica de tensin-corriente para un diodo tpico de silicio de pequea seal a una temperatura de 3000 K. Tenga en cuenta los cambios de escala.

Codo0,6 V

Anlisis de la lnea de carga

Anlisis de la lnea de carga Punto BCurva caracterstica del diodoPunto de trabajoLnea de cargaPunto AEl intercepto x del load line es el voltaje de circuito abierto y el intercepto y es la corriente de corto circuito.

El quiescent point or Q-point (punto de operacin DC) es la interseccin de la caracterstica I-V del diodo con el load line.

Aproximaciones o modelos del diodoEn el modelo del diodo ideal se equipara ste a un cortocircuito o a un circuito abierto, segn cmo est conectado.1 aproximacin: diodo ideal

Anlisis usando el modelo ideal

Hacer una suposicin razonable del estado de cada diodo

Redibujar el circuito sustituyendo los diodos en conduccin por cortocircuitos y los diodos en corte por un circuito abierto.

Mediante el anlisis de circuitos determinar la corriente en cada diodo en conduccin y el voltaje en cada diodo abierto.

Anlisis usando el modelo ideal (2) Comprobar las suposiciones hechas para cada diodo. Si hay contradiccin una corriente negativa en un diodo en conduccin, un voltaje positivo en un diodo en corte en cualquier lugar del circuito, entonces regresar al primer paso con una suposicin mejorada.

Cuando no hay contradicciones, las corrientes yvalores en el circuito se aproximan bastante a lasverdaderas.

Ejemplo mtodo de estados asumidos

Aproximacin lineal (2)Se considera que el diodo conduce sin resistencia por encima de la tensin umbral, y no conduce por debajo de la misma. Esto equivale a considerar un diodo como un interruptor o un diodo ideal en serie con una fuente de voltaje DC.VU= 0.3 V para el diodo de Ge VU= 0.7 V para el de Si.VI

Aproximacin lineal (3)La 3 aproximacin es un diodo ideal con una resistencia en serie y una fuente de tensin.0,40,60,80,2VuV = Vu + IRdDVDIRd = V/I

DIODO

Curva caracterstica del diodo de unin

Ge

T300.0310.0320.0Vi-100

Vt (mV)25.85983966926.721834324627.58382898030

Io (mA)3.00E-048.76E-042.40E-03inc5.1719679338

e/k11.601

Ego (meV)780

V (mV)I (mA)

-105.1719679338

-100-1-0.0008550442-0.0023345127

-94.8280320662-1-0.0008506116-0.0023213356

-89.6560641324-0.95-0.0008452324-0.0023054409

-84.4840961986-0.9-0.0008387045-0.0022862682

-79.3121282648-0.8-0.0008307826-0.0022631415

-74.140160331-0.24-0.000821169-0.0022352455

-68.9681923972-0.154-0.0008095024-0.0022015964

-63.7962244634-0.084-0.0007953444-0.0021610078

-58.6242565296-0.036-0.000778163-0.0021120487

-53.4522885958-0.012-0.0007573126-0.0020529927

-48.280320662-0.000253624-0.0007320096-0.0019817576

-43.1083527282-0.0002433562-0.0007013031-0.0018958316

-37.9363847944-0.0002308151-0.0006640394-0.0017921851

-32.7644168606-0.0002154974-0.0006188181-0.0016671636

-27.5924489268-0.0001967883-0.0005639399-0.0015163588

-22.420480993-0.0001739369-0.0004973425-0.0013344535

-17.2485130592-0.0001460262-0.0004165234-0.0011150339

-12.0765451254-0.000111936-0.0003184455-0.0008503633

-6.9045771916-0.0000702981-0.0001994232-0.0005311096

-1.7326092578-0.0000194414-0.000054984-0.0001460162

3.4393586760.0000426750.00012029990.0003184952

8.61132660980.00011854420.00033301540.0008788028

13.78329454360.0002112110.00059115590.0015546629

18.95526247740.00032439460.00090442180.0023699057

24.12723041120.00046263720.0012845850.0033532763

29.2991983450.00063148720.00174593140.0045394476

34.47116627880.00083772110.00230579740.0059702433

39.64313421260.00108961560.00298522180.0076961124

44.81510214640.00139728040.00380973590.0097779079

49.98707008020.00177306290.00481032340.0122890326

55.1590380140.00223204480.00602458460.0153180272

60.33100594780.00279264650.00749814890.018971692

65.50297388160.0034773670.009286390.0233788531

70.67494181540.00431368640.01145650670.0286949042

75.84690974920.00533516930.01409004770.0351072857

81.0188776830.00658281140.01728597630.0428420943

86.19084561680.00810668480.02116438950.0521720545

91.36281355060.0099679480.02587103040.0634261346

96.53478148440.01224130.03158276560.0770011465

101.70674941820.01501797840.0385142310.0933757364

106.8787173520.0184094210.04692589780.1131272621

112.05068528580.02255173850.057133860.1369521499

117.22265321960.02761117640.06952171320.1656904503

122.39462115330.03379078780.0845549690.2003554575

127.56658908710.04133858230.10279854810.2421694378

132.73855702090.05055747920.12493800890.2926067257

137.91052495470.06181746540.15180530960.353445708

143.08249288850.07557044360.18441007150.4268315288

148.25446082230.0923683690.22397751850.5153517258

153.42642875610.11288540150.27199451890.6221274651

158.59839668990.13794496160.33026545870.7509235917

163.77036462370.16855277740.40098004730.9062813756

168.94233255750.20593724810.48679560231.0936786341

174.11430049130.25159874360.59093690651.3197228759

179.28626842510.30736982020.71731738881.5923842781

184.45823635890.3754887670.87068618371.9212767093

189.63020429270.45868943651.05680659412.3179967085

194.80217222650.56031096371.28267266552.7965323722

199.97414016030.68443177741.55677200853.3737565652

205.14610809410.83603328151.88940474684.0700218474

210.31807602791.02119977672.29307057614.9098780924

215.49004396171.24736264472.78293847845.9229381004

220.66201189551.52359859553.37741674317.1449217265

225.83397982931.86099394784.09884471478.6189153405

231.00594776312.27308956154.974332262710.3968910253

236.17791569692.77642428086.036778517712.5415390789

241.34988363073.39119869527.326108157415.1284784356

246.52185156454.14208586078.890771698518.248922941

251.69381949835.059221515610.789566174222.0128974952

256.86578743216.179413534113.093844612326.5531174604

262.03775536597.547619155215.890197344732.0296681215

267.20972329979.218749274519.283705904638.6356491913

272.381691233511.259872211523.401891787546.6039833849

277.553659167313.752905396528.399508462556.2156291267

282.725627101116.797903004934.464356708967.8094869672

287.897595034920.517071482341.824341806781.7943490019

293.069562968725.059674118650.756037776598.6633126221

298.241530902530.608021507961.5950804968119.0111668171

303.413498836337.384788312474.7487802522143.555364058

308.585466770145.661949978990.7114276668173.1613172177

313.757434703955.771698068110.0828681908208.8729134819

318.929402637768.1197722684133.5910431336251.9493211509

324.101370571583.2017441547162.1193442922303.9093871176

329.2733385053101.6229062151196.7398101078366.5851904486

334.4453064391124.1225643642238.7534107995442.1866403331

339.6172743729151.6037088851289.7389363116533.379396084

344.7892423067185.1692546004351.6123241894643.3788565987

349.9612102405226.1663047163426.6986568109776.0635332916

355.1331781743276.2402148042517.8195334901936.1118039531

360.3051461081337.4006266974628.39910072841129.1668693926

365.4771140419412.102122474762.59272502431362.0357291297

370.6490819757503.3427354542925.44314351861642.9291918927

375.8210499095614.78427180451123.06996031341981.7513835421

&A

Pgina &P

Caracterstica

-1

-1

-0.95

-0.9

-0.8

-0.24

-0.154

-0.084

-0.036

-0.012

-0.000253624

-0.0002433562

-0.0002308151

-0.0002154974

-0.0001967883

-0.0001739369

-0.0001460262

-0.000111936

-0.0000702981

-0.0000194414

0.000042675

0.0001185442

0.000211211

0.0003243946

0.0004626372

0.0006314872

0.0008377211

0.0010896156

0.0013972804

0.0017730629

0.0022320448

0.0027926465

0.003477367

0.0043136864

0.0053351693

0.0065828114

0.0081066848

0.009967948

0.0122413

0.0150179784

0.018409421

0.0225517385

0.0276111764

0.0337907878

0.0413385823

0.0505574792

0.0618174654

0.0755704436

0.092368369

0.1128854015

0.1379449616

0.1685527774

0.2059372481

0.2515987436

0.3073698202

0.375488767

0.4586894365

0.5603109637

0.6844317774

0.8360332815

1.0211997767

1.2473626447

1.5235985955

1.8609939478

2.2730895615

2.7764242808

3.3911986952

4.1420858607

5.0592215156

6.1794135341

7.5476191552

9.2187492745

11.2598722115

13.7529053965

16.7979030049

20.5170714823

25.0596741186

30.6080215079

37.3847883124

45.6619499789

55.771698068

68.1197722684

83.2017441547

101.6229062151

124.1225643642

151.6037088851

185.1692546004

226.1663047163

276.2402148042

337.4006266974

412.102122474

503.3427354542

614.7842718045

&A

Pgina &P

Io

V (V)

I (mA)

Caracterstica (2)

0.0150179784

0.018409421

0.0225517385

0.0276111764

0.0337907878

0.0413385823

0.0505574792

0.0618174654

0.0755704436

0.092368369

0.1128854015

0.1379449616

0.1685527774

0.2059372481

0.2515987436

0.3073698202

0.375488767

0.4586894365

0.5603109637

0.6844317774

0.8360332815

1.0211997767

1.2473626447

1.5235985955

1.8609939478

2.2730895615

2.7764242808

3.3911986952

4.1420858607

5.0592215156

6.1794135341

7.5476191552

9.2187492745

11.2598722115

13.7529053965

16.7979030049

20.5170714823

25.0596741186

30.6080215079

37.3847883124

45.6619499789

55.771698068

68.1197722684

83.2017441547

101.6229062151

124.1225643642

151.6037088851

185.1692546004

226.1663047163

276.2402148042

337.4006266974

412.102122474

503.3427354542

614.7842718045

&A

Pgina &P

Vcodo

V = Vcodo + IRd

V = e0+ IRd

V (mV)

I (mA)

Io=f(t)

-1-0.0008550442-0.0023345127

-1-0.0008506116-0.0023213356

-0.95-0.0008452324-0.0023054409

-0.9-0.0008387045-0.0022862682

-0.8-0.0008307826-0.0022631415

-0.24-0.000821169-0.0022352455

-0.154-0.0008095024-0.0022015964

-0.084-0.0007953444-0.0021610078

-0.036-0.000778163-0.0021120487

-0.012-0.0007573126-0.0020529927

-0.000253624-0.0007320096-0.0019817576

-0.0002433562-0.0007013031-0.0018958316

-0.0002308151-0.0006640394-0.0017921851

-0.0002154974-0.0006188181-0.0016671636

-0.0001967883-0.0005639399-0.0015163588

-0.0001739369-0.0004973425-0.0013344535

-0.0001460262-0.0004165234-0.0011150339

-0.000111936-0.0003184455-0.0008503633

-0.0000702981-0.0001994232-0.0005311096

-0.0000194414-0.000054984-0.0001460162

0.0000426750.00012029990.0003184952

0.00011854420.00033301540.0008788028

0.0002112110.00059115590.0015546629

0.00032439460.00090442180.0023699057

0.00046263720.0012845850.0033532763

0.00063148720.00174593140.0045394476

0.00083772110.00230579740.0059702433

0.00108961560.00298522180.0076961124

0.00139728040.00380973590.0097779079

0.00177306290.00481032340.0122890326

0.00223204480.00602458460.0153180272

0.00279264650.00749814890.018971692

0.0034773670.009286390.0233788531

0.00431368640.01145650670.0286949042

0.00533516930.01409004770.0351072857

0.00658281140.01728597630.0428420943

0.00810668480.02116438950.0521720545

0.0099679480.02587103040.0634261346

0.01224130.03158276560.0770011465

0.01501797840.0385142310.0933757364

0.0184094210.04692589780.1131272621

0.02255173850.057133860.1369521499

0.02761117640.06952171320.1656904503

0.03379078780.0845549690.2003554575

0.04133858230.10279854810.2421694378

0.05055747920.12493800890.2926067257

0.06181746540.15180530960.353445708

0.07557044360.18441007150.4268315288

0.0923683690.22397751850.5153517258

0.11288540150.27199451890.6221274651

0.13794496160.33026545870.7509235917

0.16855277740.40098004730.9062813756

0.20593724810.48679560231.0936786341

0.25159874360.59093690651.3197228759

0.30736982020.71731738881.5923842781

0.3754887670.87068618371.9212767093

0.45868943651.05680659412.3179967085

0.56031096371.28267266552.7965323722

0.68443177741.55677200853.3737565652

0.83603328151.88940474684.0700218474

1.02119977672.29307057614.9098780924

1.24736264472.78293847845.9229381004

1.52359859553.37741674317.1449217265

1.86099394784.09884471478.6189153405

2.27308956154.974332262710.3968910253

2.77642428086.036778517712.5415390789

3.39119869527.326108157415.1284784356

4.14208586078.890771698518.248922941

5.059221515610.789566174222.0128974952

6.179413534113.093844612326.5531174604

7.547619155215.890197344732.0296681215

9.218749274519.283705904638.6356491913

11.259872211523.401891787546.6039833849

13.752905396528.399508462556.2156291267

16.797903004934.464356708967.8094869672

20.517071482341.824341806781.7943490019

25.059674118650.756037776598.6633126221

30.608021507961.5950804968119.0111668171

37.384788312474.7487802522143.555364058

45.661949978990.7114276668173.1613172177

55.771698068110.0828681908208.8729134819

68.1197722684133.5910431336251.9493211509

83.2017441547162.1193442922303.9093871176

101.6229062151196.7398101078366.5851904486

124.1225643642238.7534107995442.1866403331

151.6037088851289.7389363116533.379396084

185.1692546004351.6123241894643.3788565987

226.1663047163426.6986568109776.0635332916

276.2402148042517.8195334901936.1118039531

337.4006266974628.39910072841129.1668693926

412.102122474762.59272502431362.0357291297

503.3427354542925.44314351861642.9291918927

614.78427180451123.06996031341981.7513835421

&A

Pgina &P

300 K

310 K

320 K

V (mV)

I (mA)

Zener

-1

-1

-0.95

-0.9

-0.8

-0.24

-0.154

-0.084

-0.036

-0.012

-0.000253624

-0.0002433562

-0.0002308151

-0.0002154974

-0.0001967883

-0.0001739369

-0.0001460262

-0.000111936

-0.0000702981

-0.0000194414

0.000042675

0.0001185442

0.000211211

0.0003243946

0.0004626372

0.0006314872

0.0008377211

0.0010896156

0.0013972804

0.0017730629

0.0022320448

0.0027926465

0.003477367

0.0043136864

0.0053351693

0.0065828114

0.0081066848

0.009967948

0.0122413

0.0150179784

0.018409421

0.0225517385

0.0276111764

0.0337907878

0.0413385823

0.0505574792

0.0618174654

0.0755704436

0.092368369

0.1128854015

0.1379449616

0.1685527774

0.2059372481

0.2515987436

0.3073698202

0.375488767

0.4586894365

0.5603109637

0.6844317774

0.8360332815

1.0211997767

1.2473626447

1.5235985955

1.8609939478

2.2730895615

2.7764242808

3.3911986952

4.1420858607

5.0592215156

6.1794135341

7.5476191552

9.2187492745

11.2598722115

13.7529053965

16.7979030049

20.5170714823

25.0596741186

30.6080215079

37.3847883124

45.6619499789

55.771698068

68.1197722684

83.2017441547

101.6229062151

124.1225643642

151.6037088851

185.1692546004

226.1663047163

276.2402148042

337.4006266974

412.102122474

503.3427354542

614.7842718045

&A

Pgina &P

Vz

V (mV)

I (mA)

Curva caracterstica de un diodo Zener

Modelo del diodo para pequea seal (con fuente de dc y ac)Dos modelos: De gran seal (CD) De pequea seal (AC) Modelo de gran seal: En un punto de operacinespecfico punto de operacin Q Modelo de pequea seal Pequea variacin alrededorde un punto de operacin Considera slo el efecto defuentes de CA Aplicaciones de modelo depequea seal Anlisis de CA, respuesta defrecuencia

Tres modelos de diodo

Figura 3.11. Rectificador de media onda con carga resistiva.(a) Diagrama del circuito (b) Tensin de la fuente en funcin del tiempo (c) Tensin de la carga en funcin del tiempo Diodo ideal 0,7 VDiodorealVmsen ( t)

Figura 3.23. Puertas lgicas con diodos.(a) Puerta OR(b) Puerta AND

Figura 3.31. Curva caracterstica del diodo, mostrando el punto Q.Punto Q

Figura 3.32. Corrientes de los diodos.

*****Se elimina el smbolo delta, y designa a los cambios de corriente y tensin, a partir de los valores del punto Q, como vd y id. Por tanto, para esas pequeas seales de alterna, se escribe la ecuacion 4

*****