Share this document with a friend

Description:

Chapter 4 – Bipolar Junction Transistors (BJTs). Introduction. http://engr.calvin.edu/PRibeiro_WEBPAGE/courses/engr311/311_frames.html. Physical Structure and Modes of Operation. A simplified structure of the npn transistor. Physical Structure and Modes of Operation. - PowerPoint PPT Presentation

Embed Size (px)

Popular Tags:

of 77
/77

Transcript

Chapter 4 – Bipolar Junction Transistors (BJTs)

Introduction

http://engr.calvin.edu/PRibeiro_WEBPAGE/courses/engr311/311_frames.html

A simplified structure of the npn transistor.

Physical Structure and Modes of Operation

A simplified structure of the pnp transistor.

Physical Structure and Modes of Operation

Physical Structure and Modes of Operation

Mode EBJ CBJ

Active Forward ReverseCutoff Reverse ReverseSaturation Forward Forward

Current flow in an npn transistor biased to operate in the active mode, (Reverse current components due to drift of thermally generated minority carriers are not shown.)

Operation of The npn Transistor Active Mode

Profiles of minority-carrier concentrations in the base and in the emitter of an npn transistor operating in the active mode; vBE 0 and vCB 0.

Operation of The npn Transistor Active Mode

The Collector Current

The Base Current

Physical Structure and Modes of Operation

i C I S e

v BE

V T

i B

i C

I S

e

v BE

V T

iE iC iB 1

iC

1

IS e

vBE

VT

iC IE

1

Operation of The npn Transistor Active Mode

Large-signal equivalent-circuit models of the npn BJT operating in the active mode.

Equivalent Circuit Models

The Constant n

The Collector-Base Reverse Current

The Structure of Actual Transistors

Current flow in an pnp transistor biased to operate in the active mode.

The pnp Transistor

Two large-signal models for the pnp transistor operating in the active mode.

The pnp Transistor

Circuit Symbols and Conventions

C

B

E

C

B

E

Circuit Symbols and Conventions

Example 4.1 VCC 15 IC1 0.001 100 VBE 0.7 VEE 15 VT 0.025

Design circuit such that

VC 5 IC2 0.002

RCVCC VC

IC2 RC 5 10

3

Since VBE=0.7V at IC=1mA, the value of VBE at IC=2mA is

VBE 0.7 VT ln2

1

VBE 0.717

VE VBE VE 0.717

1 IE

IC2

IE 2.02 10

3

REVE VEE( )

IE RE 7.071 10

3

i C I S e

v BE

V TIB

IC2

IB 2 10

5

E

BC

Example 4.1

IBIC2

IB 2 10

5

Example 4.1

Summary of the BJT I-V Relationships in the Active Mode

iC IS e

vBE

VT iB

iC

IS

e

vBE

VT iE

iC

IS

e

vBE

VT

Note : for pnp transitor, replace vBE for vEB

iC iE iB 1 iEiE

1

iC iB iE 1 iB

iE

1VT 25mV

Exercise 4.8

Exercise 4.9

The Graphical Representation of the Transistor Characteristics

The Graphical Representation of the Transistor Characteristics

Temperature Effect (10 to 120 C)

The iC-vCB characteristics for an npn transistor in the active mode.

Dependence of ic on the Collector Voltage

Dependence of ic on the Collector Voltage

(a) Conceptual circuit for measuring the iC-vCE characteristics of the BJT. (b) The iC-vCE characteristics of a practical BJT.

Dependence of ic on the Collector Voltage – Early Effect

I C I S e

v BE

VT 1v CE

V A

VA – 50 to 100V

Dependence of ic on the Collector Voltage – Early Effect

Nested DC Sweeps

Example

Example

Example

Monte Carlo Analysis – Using PSpice

Monte Carlo Analysis – Using PSpice

Monte Carlo Analysis – Using PSpice

Probe Output Ic(Q), Ib(Q), Vce

Monte Carlo Analysis – Using PSpice

(a) Conceptual circuit to illustrate the operation of the transistor of an amplifier.

(b) The circuit of (a) with the signal source vbe eliminated for dc (bias) analysis.

The Transistor As An Amplifier

The Collector Current and The Transconductance

The Base Current and the Input Resistance at the Base

The Emitter Current and the Input Resistance at the Emitter

Linear operation of the transistor under the small-signal condition: A small signal vbe with a triangular waveform is superimpose din

the dc voltage VBE. It gives rise to a collector signal current ic, also of triangular waveform, superimposed on the dc current IC. Ic = gm

vbe, where gm is the slope of the ic - vBE curve at the bias point Q.

The Transistor As An Amplifier

Two slightly different versions of the simplified hybrid- model for the small-signal operation of the BJT. The equivalent circuit in (a) represents the BJT as a voltage-controlled current source ( a transconductance amplifier) and that in (b) represents the BJT as a current-controlled current source (a current amplifier).

Small-Signal Equivalent Circuit Models

Two slightly different versions of what is known as the T model of the BJT. The circuit in (a) is a voltage-controlled current source representation and that in (b) is a current-controlled current source representation. These models explicitly show the emitter resistance re rather than the base resistance r featured in the hybrid- model.

Small-Signal Equivalent Circuit Models

Signal waveforms in the circuit of Fig. 4.28.

Fig. 4.30 Example 4.11: (a) circuit; (b) dc analysis; (c) small-signal model; (d) small-signal analysis performed directly on the circuit.

Fig. 4.34 Circuit whose operation is to be analyzed graphically.

Fig. 4.35 Graphical construction for the determination of the dc base current in the circuit of Fig. 4.34.

Fig. 4.36 Graphical construction for determining the dc collector current IC and the collector-to-emmiter voltage VCE in the circuit of

Fig. 4.34.

Fig. 4.37 Graphical determination of the signal components vbe, ib, ic, and vce when a signal component vi is superimposed on the dc

voltage VBB (see Fig. 4.34).

Fig. 4.38 Effect of bias-point location on allowable signal swing: Load-line A results in bias point QA with a corresponding VCE which

is too close to VCC and thus limits the positive swing of vCE. At the other extreme, load-line B results in an operating point too close to

the saturation region, thus limiting the negative swing of vCE.

Fig. 4.44 The common-emitter amplifier with a resistance Re in the emitter. (a) Circuit. (b) Equivalent circuit with the BJT replaced

with its T model (c) The circuit in (b) with ro eliminated.

Fig. 4.45 The common-base amplifier. (a) Circuit. (b) Equivalent circuit obtained by replacing the BJT with its T model.

Fig. 4.46 The common-collector or emitter-follower amplifier. (a) Circuit. (b) Equivalent circuit obtained by replacing the BJT with its T model. (c) The circuit in (b) redrawn to show that ro is in parallel with RL. (d) Circuit for determining Ro.

An npn resistor and its Ebers-Moll (EM) model. ISC and ISE are the scale or saturation currents of diodes DE (EBJ) and DC (CBJ).

More General – Describe Transistor in any mode of operation.

Base for the Spice model.

Low frequency only

A General Large-Signal Model For The BJT: The Ebers-Moll Model

iDE ISE e

vBE

VT1

iDC ISC e

vBC

VT1

ISC > ISE (2-50)

A General Large-Signal Model For The BJT: The Ebers-Moll Model

IDE ISE e

vBE

VT1

IDC ISE e

vBC

VT1

Fforwarded of the transistor source (close to 1)

Rreverse of the transistor source (0.02 - 0.5

A General Large-Signal Model For The BJT: The Ebers-Moll Model – Terminal Currents

F ISE R ISC IS

iE iDE R iDC iC iDC R iDE

iB 1 F iDE 1 R iDC

F

F

1 FiE

IS

Fe

vBE

VT1

IS e

vBC

VT1

R

R

1 RiC

IS

Fe

vBE

VT1

IS

Re

vBC

VT1

iB

IS

Fe

vBE

VT1

IS

Re

vBC

VT1

iE

IS

Fe

vBE

VT IS 11

F

iC IS e

vBE

VT IS1

R1

iB

IS

Fe

vBE

VT IS1

F

1

R

A General Large-Signal Model For The BJT: The Ebers-Moll Model – Forward Active Mode

Since vBC is negative and its magnitudeIs usually much greater than VT the Previous equations can be approximatedas

A General Large-Signal Model For The BJT: The Ebers-Moll Model – Normal Saturation

Collector current will be forced IB forced F

In saturation both junctions are forwarded biased. Thus VBE and VBCare positive and their values greater than VT.Making these approximations and substituting

iB IBand iC forced IB

results in two equations that can be solved to obtain VBE and VBC.The saturatuion voltage can be obtained as the difference between the two:

VCEsat VT ln

1forced 1

R

1forced

F

A General Large-Signal Model For The BJT: The Ebers-Moll Model – Reverse Mode

I1

I2IB

Note that the currents indicated have positive values. Thus, since ic = -I2 and iE = -I1, both iC and IE will be negative. Since the roles of the emitter and collector are interchanged, the transistor in the circuit will operate in the active mode (called the reverse active mode) when the emitter-base junction is reverse-biased. In such a case

I1 = beta_R . IB

This circuit will saturate (reverse saturation mode) when the emitter-base junction becomes forward-biased.

I1/IB < beta_R

A General Large-Signal Model For The BJT: The Ebers-Moll Model – Reverse Saturation

VECsat VT ln

11

F

I1

IB

1

F

1I1

IB

1

R

We can use the EM equations to find the expression of VECSat

From this expression, it can be seen that the minimum VECSat is obtained when I1 = 0. This minimum is very close to zero.

The disadvantage of the reverse saturation mode is a relatively long turnoff time.

VE 4.56VE VCC I1 RC

I1 4.4 104I1 R IB

RC 1000a) for RC = 1 K, assume that the transitor is in the reverse active mode. thus

IB 4.4 103IB

VI VBRB

VB 0.6From VBC = 0.6

Calculate approximate values ofe VE for the following cases:RC = 1K, 10K, 100K

F 50R 0.1

VBC 0.6VCC 5VI 5RB 1000

For the circuit below, let

A General Large-Signal Model For The BJT: The Ebers-Moll Model – Example

the BJT is sauratedI1 R IBSince

mVVECsat 3.5VECsat VT ln

11

F

I1

IB

1

F

1I1

IB

1

R

VT 25a better estimate for VE is to use the equation below (4.115)

I1 5 104I1

VCC 0RC

Since VECsat is liekly to be very small, we can assume VE = 0, and

RC 10000b) For RC = 100K, assume reverse saturation mode

Since VE = VB, the BJT is still in the reverse active mode.

VE 0.6VE VCC I1 RC

I1 4.4 104I1 R IB

RC 10000b) For RC = 10K, assume reverse active mode

A General Large-Signal Model For The BJT: The Ebers-Moll Model – Example

The transport model of the npn BJT. This model is exactly equivalent to the Ebers-Moll model. Note that the saturation currents of the diodes are given in parentheses and iT is defined by Eq. (4.117).

A General Large-Signal Model For The BJT: The Ebers-Moll Model – Transport Model npn BJT

Basic BJT digital logic inverter.

Basic BJT Digital Logic Inverter.

vi high (close to power supply) - vo lowvi low vo high

Sketch of the voltage transfer characteristic of the inverter circuit of Fig. 4.60 for the case RB = 10 k, RC = 1 k, = 50, and VCC =

5V. For the calculation of the coordinates of X and Y refer to the text.

Basic BJT Digital Logic Inverter.

(a) The minority-carrier concentration in the base of a saturated transistor is represented by line (c). (b) The minority-carrier charge stored in the base can de divided into two components: That in blue produces the gradient that gives rise to the diffusion current across the base, and that in gray results in driving the transistor deeper into saturation.

The Voltage Transfer Characteristics

The ic-vcb or common-base characteristics of an npn transistor. Note that in the active region

there is a slight dependence of iC on the value of vCB. The result is a finite output resistance

that decreases as the current level in the device is increased.

Complete Static Characteristics, Internal Impedances, and Second-Order Effects – Common Base

Avalanche

Saturation

Slope

The hybrid- model, including the resistance r, which models the effect of vc on ib.

Complete Static Characteristics, Internal Impedances, and Second-Order Effects – Common Base

Common-emitter characteristics. Note that the horizontal scale is expanded around the origin to show the saturation region in some detail.

Complete Static Characteristics, Internal Impedances, and Second-Order Effects – Common-Emitter

An expanded view of the common-emitter characteristics in the saturation region.

Complete Static Characteristics, Internal Impedances, and Second-Order Effects – Common-Emitter

The Transistor Beta

Transistor Breakdown

Internal Capacitances of a BJT

Cde F

IC

VT Base charging or Diffusion capacitance

Base Emitter Junction capacitanceCje

Cje0

1VBE

V0e

m

m - 0.2 - 0.5 grading coefficient

CC0

1VCB

V0c

m Collector Base Juntion Capacitance

C Cde Cje

r x

The Cut-Off Frequency

The Spice BJT Model and Simulation Examples

The Spice BJT Model and Simulation Examples

The Spice BJT Model and Simulation Examples

.model Q2N2222-X NPN(

Is=14.34f

Xti=3

Eg=1.11

Vaf=74.03

Bf=200

Ne=1.307

Ise=14.34f

Ikf=.2847

Xtb=1.5

Br=6.092

Nc=2

Isc=0

Ikr=0

Rc=1

Cjc=7.306p

Mjc=.3416

Vjc=.75

Fc=.5

Cje=22.01p

Mje=.377

Vje=.75

Tr=46.91n

Tf=411.1p

Itf=.6

Vtf=1.7

Xtf=3

Rb=10)

*National pid=19

case=TO18 88-09-07 bam creation

The Spice BJT Model and Simulation Examples

The Spice BJT Model and Simulation Examples

BJT Modeling - Idealized Cross Section of NPN BJT

Sunday, Marc h 08, 1998

{D oc } --

N5FC 2N2222 DS B /CW TRA NS CE IV E R

C

1 2

Title

S ize Document Number Rev

Date: S heet of

12V R EG

8V R EG

12V R EG

12V R EG

12V R EG

12V R EG

8V R EG

12V RE G

12V R EG

12V RE G

12V R EG

8V R EG

RX _IN

RX _ON

TX _V FO

TX _ON

RX _B FO

DE T_A UD

TX V FO

DS B

TX _ON

RX _ON

TX _ON

RX _IN

DS B

TX _ONTX _ON

TX _ON

TX _ON

RX _ON

TX _ON

RX _ON

DRV _COLL

DRV _COLL

C 18120pF

C 20 56pFC 19 6.8pF

R 7560

Q42N 2222A

R 43.2K

C 70.01uF

R 134.7

C 4

0.1uF

D 11N 4148

D 2

1N 4148C 80.01uF

R 51K

R 101K

C 10.01uF

T3

TR I XFMR

C 23 180pF

C 260.01uF

R 1575

C 21 180pF

T1

BIF XFMR

C 228-80pF

L3

1mHC 248-80pFL5

2.0uH

L42.0uH

R 42

15K

R 2149.9K/1%

R 451.00K/1%

R 3833.2K/1%

L10 1mH R 31

1.00M/1%

C 450.01uF L11

5.6uH

C 51

1000pF

L15100uH

R 28

100K POT

R 245K POT

C 49

0.01uF

C 541000pF

R 2727.4K/1%

R 3515.0K/1%

L6 100uH

C 350.01uF

Q92N 2222A

C 310.01uF

C 53

0.022uF

Q102N 2222A

C 320.01uF

R 37

10K

R 40

33K

C 16 0.022uF

Q82N 2222A

C 480.01uF

R 2647

C 59

0.022uF

C 5056pF

L12

1mH

D 542pF

R 321K

R 43

10K

C 473-36pF

R 44330

D 61N 4148

L16

1mH

C 5

10uF N P C 110.1uF

L1 82mH

C 90.047uF

C 130.047uF

C 14

0.068uF

C 17

10uF N P

R 81K POT

L2 82mH

C 120.068uF

C 100.068uF

Q32N 2222A

Q22N 2222A

Q12N 2222A

R 9100

R 310K

R 11K

R 6

10K

R 210K

R 11

27K

R 12

51K

+C 2

100uF

C 30.1uF

T2

2K/SPKR

J 1

PH J AC K

C 3610uF N P

C 410.22uF

L8 47mH

C 390.1uF

C 430.1uF

C 44

0.033uF

L9 47mH

C 42

0.047uF

C 40

0.033uF

C 37

10uF N P

Q72N 2222A

Q62N 2222A

Q52N 2222A

R 25100

R 2010K

R 171K

R 22

10K

R 1810K

R 3410K

R 29

27K

R 30

51K+

C 4610uF

+C 27

100uF

C 280.1uF

R 192K

T4

TR I XFMRD 41N 4148

D 31N 4148

L7

1mH

+

C 30

10uFC 34

0.01uF

R 16

100 POT

E 1

E 2

T5

600/3K

R 651.0R 66

10-1/2W

R 71

470-1/2W

+ C 7647uF

R 73475/1%

R 64

10-1/2W

R 77475/1%

D 196.2V/1W

D 10

1N 4002

D 166.2V/1W

C 75

0.1uF

R 671.0

C 89

0.1uF

R 59

10-1/2W

D 111N 5822

C 82

0.1uF

R 72357/1%

R 68

1K

C 91

0.1uF

Q222N 2222A

Q192N 2222A

Q162N 2222A

Q182N 2222A

Q202N 2222A

D 12

1N 4002

Q172N 2222A

R 69

75.0/1%

C 83

0.1uF

+ C 7747uF

D 71N 4148

R 1410K

+

C 1510uF

C 940.1uF

C 920.01uF + C 93

47uF

Q152N 2222A

C 81470pF

R 74

2K

C 69

0.01uF

J 5

BN C

C 79470pF

C 780.1uF

L201.0uH

C 88

0.1uF

R 76

2K POT

C 70

0.1uF

L22 22uH

L211.0uH

R 7020

R 55

2K

R 6220

Q212N 2222A

T7

3:1:1

C 801000pF

T8BIF C H OKE

T9

C 71

120pF

D 14

1N 4148

R 5615K

C 840.01uF

R 75 220

S3

R 6320

R 61

36

R 60

36

C 68

0.01uF

Q112N 2222A

R 5047

R 49220

R 46

2.2K

R 3947

C 570.1uF

C 63

82pF

C 628-80pF

R 52220

C 580.1uF

C 61

0.01uF

R 5339

Q122N 2222A

R 47

1K

R 51TBD

L14100uH

D 188.2V/1W

C 90

0.1uF

L13100uH

R 5715K

L191mH

R 23100

C 38

0.01uFS1

R 361K

R 33

1K

C 522-22pF

D 81N 4148

R 41

3.2K

C 560.01uF

S2

J 3

R 48

470-1/2W

Q142N 2222A

Q132N 2222A

D 9

1N 4002

L17 100uH

C 640.01uF

C 650.01uF

J 2C 660.01uF

C 670.01uF

L18 100uH

E 3

E 4

+C 6

10uF

+

C 33

10uF

+C 29

10uF

+C 25

10uF

C 8682pF

C 858-80pF

R 5820 C 72

0.1uF

C 550.1uF

S5

C 1010.47uF

C 1020.47uF

C 60

0.01uF

T6

9:1

R 541500

D 17

1N 4148

C 730.01uF

+C 74

220uF

J 4

F31A SB

F2 1A SB

S7

C ?0.01uF

C ?0.01uF

L? 100uH

C 870.01uF

RF PREAMP

RX MIXER

D5:18-36pF(6 - 1.5V)6.95 -7.35 MHz

VF0 / BFO

MAINTUNE

BANDSPREAD

RCVR FILTER

RXGAIN

HEADPHONES(LO-Z)

2K 12 OHM

CARRIERBALANCE

BALMODULATOR

TO LO-ZMIC

2.75 KHz LOW PASS FILTER

RX AUDIO AMP

TX AUDIO AMP

I-LIM =0.42A

12V REGULATOR

8V REGULATOR

BIAS(SET FORIc=1.5mAQUIESCENT)

PUSH-PULLPOWER AMP1.5W PEP

(THERMAL COUPLING)

LOW-PASSRF FILTER

20dB0dB

RCVRATTEN

5uH

39-200AS REQDTO ADJGAIN

RFDRIVERS

DSB CW

USB O/S

LSB O/S

CENTER = ZERO O/S

16 VDCUNREG

13 VDC (BATT)

KEY

PTT

CONTROL CKT

5uH

BPLP

ANTENNA50 OHMS

D ESIGN ED BYM. N OR TH R U PN 5FC

F-LP = 2.5KHz / F-BP = 800Hz

PWRON/OFF

L4, L526t AWG32 ONAMIDON T37-6

T1BIFILAR XFMR2 x 10t AWG32 ONAMIDON FT37-61

T3TRIFILAR XFMR3 x 10t AWG32 ONAMIDON FT37-61

T4TRIFILAR XFMR3 x 12t AWG32 ONAMIDON FT37-61

T5PRI: 360t AWG40SEC: 800t AWG40ON AMIDONPC1408-77 POT CORE

T2PRI: 650t AWG40SEC: 50t AWG32ON AMIDONPC1408-77 POT CORE

T8: BIFILAR CHOKE2 x 8t AWG26 ONAMIDON FT50-61

T9: PRI: 2 x 8t AWG 26SEC: 7t AWG 26ON AMIDON T68-6

T7: PRI: 36t AWG 32SEC: 2 x 9t AWG 32ON AMIDON T50-2

T6: PRI: 36t AWG 32SEC: 4t AWG 32ON AMIDON T50-6

The Spice BJT Model and Simulation Examples

Recommended