ECE 2C, notes set 4: Transistor Amplifiers basic ... · Learn loadline analysis of transistor ... Fundmentals of frequency and transient response. Transistor high - frequency

class notes, M. Rodwell, copyrighted 2013

ECE 2C, notes set 4: Transistor Amplifiers ...basic considerations

Mark Rodwell

University of California, Santa Barbara

[email protected] 805-893-3244, 805-893-3262 fax


Goals of this note set:

...) junction, tunnel tube,Vacuum (diode,

elementcircuit nonlinear any or *

circuits *r transistoof analysis signal-small ACLearn

circuits *r transistoof analysis bias DCLearn

circuits *r transistoof analysis loadlineLearn


Transistor Amplifiers: Comments

response. transientandfrequency of sFundmental

models.frequency -high Transistor

analysis. signal Small models. signal Small Loadlines. analysis. bias DC

design.circuit active of principles basic on tointroducti :2C ECEIn

ECE2C.in available weeksfew given theapproach thisecannot tak we***

weeks.few ain learned becan ICs )multistage(complex real mastered,set toolthis With

concepts. theseof up-build long involves s teach thiobest way t The

response.Frequency

coupling. DCdirect vs.AC s. techniqueBiasing

analysis. signal small vsDC models device stages. Basic

Weeks20 :detailgreat in circuitsr transisto:137AB

backgroundmuch requiresdesign multistagein Expertise


Transistor Amplifier Examples

receiver radioin

amplifier Tuned

AmpPower Audio 1980s) (Archaic

converter) digital-analog of(part circuit hold-Track

https://commons.wikimedia.org/wiki/File:Single_Supply_CMOS_OpAmp.svg

AMP-OP CMOScurrentoutput maximum

high with veryamp-opan Simply,


Transistor Circuit Examples

radios)in conversion (frequency

mixer FET

)generation (signal

oscillator Transistor

amplifierpower smitter Radar tranhttp://en.wikipedia.org/wiki/File:CMOS_NAND.svg

gate logic CMOS


Elementary Common-Source Amplifier

analysis step-by-step :First

output. on the appears signal amplifiedAn

applied. is signalinput An

network bias DC a and supply,power a load, a r, transistoa isamplifier The


CS Amplifier: DC Transfer Characteristics

inout VV offunction a as compute usLet



)1())(2/(

sticscharacteri V-I FET :lines Blue

2

, DSthgsggoxD VVVLWcI

gsV Varying

law. sOhm' from /)(

loadline the:line Red

LoutDDload RVVI

FET) channel-longfor suitable modelmobility fashioned-old(



loadline. theand

sticscharacteri FET theofon intersecti thefinding and

settingby found is tageoutput vol the,any At gsinoutin VVVV

stics.characteri transfer vs. plot the tous Allows outin VV

ly.mechanical work hardBut easy. andclear ly Conceptual

gsin VV Varying


CS Amplifier: S.S. Voltage Gain by Loadline Method

. from find tomethod graphical using :Here inout VV

ly.mechanical work hardBut easy. andclear ly Conceptual

right). (left,shown methods Two

gsin VV Varying


Loadline methods: Intuitive but Inefficient.

methods loadlineby analyze complex to far too are ICs Real

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Method #2a: Finding the DC Bias Conditions

mA 16.0)1()3.07.0)(mA/V 1(

)1())(2/(

:Analysis

22

2

DS

DSthgsggoxD

VVV

VVVLWcI

V10/1

V 3.0

mA/V1)2/(

:FET

2

th

ggox

V

LWc

:Parameters Example

V 7.0

k 1.1

V 5.2

Circuit

,

DCin

L

dd

V

R

V

*ignore

analysis. signal small

in the term)1( theignorenot Do

.accuratelyfairly yet quickly thiscalculate

to trickssomelearn willECE137A weIn

Hard. formulas. quadratic

solving involves analysis DC thenot, do weIf

error. small some causes thisDoing

analysis. bias

in the term)1( theignoring are we*

DS

DS

V

V

V. 74.0

m)mA)(1.1kOh16.0( 2.5V

,

LDDDDCout RIVV


Method #2a: DC Bias Solution


Method #2b: Find the FET Small-Signal Parameters

RDS

gmVGS

VGS

D

S

G

D

DS

D

DS

D

ds

ds

DSthgsggox

GS

Dm

DSthgsggoxD

IV

I

V

I

RG

VVVLWcV

Ig

VVVLWcI

1

1

eConductancOutput

)1)()(/(

ctanceTranscondu

)1())(2/(

currentDrain

:Recall

2


Method #2b: Find the FET Small-Signal Parameters

RDS

gmVGS

VGS

D

S

G

62.5k

1S 16

10V

mA16.01

mS 0.856

)V/10V74.01)(V3.0V7.0)(mA/V2(

)1)()(/(

:Analysis

2

D

ds

ds

DSthgsggoxm

IR

G

VVVLWcg

V10/1

V 3.0

mA/V1)2/(

:FET

2

th

ggox

V

LWc

:Parameters Example

mA 16.0

V 7.0

V 7.0

conditions Bias

D

DS

gs

I

V

V


Method #2c: Find the Small-Signal Equivalent Circuit

oltage.constant v afor 0 Because

circuits-short with

voltagessupply) & (biasconstant Replaced 2)

model signal-small its

r with transisto theReplace 1)

circuit In this

V

inVoutV

signals. small are that these

implicit as taken isit

:droppedbeen has

notation "" The

circuit. equivalent

signal-small theis This

V


Method #2c: Find the small-signal gain

8.0- ofgain voltagea hascircuit The

0.8

)k 35.9mS)(856.0(

:law sOhm' From

k 35.9

1k1||k5.62||

resistance load equivalent

:Analysis

,

Leqm

in

out

ininLeqmout

DSLeqL

RgV

V

VVRgV

RRR

k 5.62

mS 856.0

:FET

DS

m

R

g

:Parameters Example

k 11

Circuit

LR


Comments

4.-1on focus will weECE2C,In

etc. voltage,signal maximum find tohinqueother tec use 5)

interest). of parametersother gain, voltagefind (to analyze 4)

circuit equivalent signal smallcircuit active draw 3)

models signal smallr transistofind 2)

math)by ( conditions bias DC Find 1)

:analysiscircuit Active

stics)characteri transfer gate logic ,amplifierspower :(except

circuits. sophomore outside usedrarely are...but

tool... teachinggood a are Loadlines


Example: Complementary MOS (CMOS) Amplifier

V. 5.0 :Bias

V 0.1 :Supply

)V10/1()V3.0)(mA/V 1( : *sticscharacteri V-I FET

,

22

DCin

DD

DSgsD

V

V

VVI

FET-P for the needed changessign ignoring FETs,both For *


CMOS Amplifier: Graphical DC Bias Analysis

PFETDNFETD II ,,

DCinNFETgs VV ,,

DCinDDPFETgs VVV ,,

DCoutNFETDS VV ,,

DCoutDDPFETds VVV ,,

graph single aon ipsrelationsh theserepresent :Next

sticscharacteri NFET

sticscharacteri PFET


CMOS Amplifier: Graphical DC Bias Analysis

graph single aon

ipsrelationsh theseRepresent

work.hard isit but

clear, is procedure theagain, Once

. versus ofplot a

thisfrom makecan we...and

outin VV

Volts. 5.0

when Volts 5.0

thatfound have we:Note

in

out

V

V


CMOS Amplifier: FET Small-Signal Parameters

:Parameters Example

V10/1

V 3.0

mA/V1)2/(

:FET

2

th

ggox

V

LWc

V 5.0

V 5.0

conditions Bias

DS

gs

V

V

250k

1S 0.4

10V

A 041

A.40)V3.0V5.0)(mA/V2(

) term theskip())(2/(

mS 0.42

)V/10V5.01)(V3.0V5.0)(mA/V2(

)1)()(/(

:FETs)both for parameters (same Analysis

22

2

2

D

ds

ds

DSthgsggoxD

DSthgsggoxm

IR

G

VVVLWcI

VVVLWcg


CMOS Amplifier: Small-Signal Equivalent Circuit

circuits.open with

sourcescurrent DC Replace

circuits.-short with sources

DC andsupply Power Replace

model. SSwith

symbol FET replacingwhen

G-G D,-D S,-Sconnect :careful Be

model. signal smallit with

FETeach Replace

:Steps


CMOS Amplifier: Small-Signal Equivalent Circuit

105

S 0.4S 0.4

mS 42.0mS 42.0

)/()(

:Analysis

shown. as simplies, usCircuit th

parallel.in are elements

PFET and TNFE all that Note

,,

,,

,,,,

in

out

PDSNDS

PmNm

in

out

inPDSNDSPmNmout

V

V

GG

gg

V

V

VGGggV

Documents

ECE 2C, notes set 4: Transistor Amplifiers basic ... · Learn loadline analysis of transistor ... Fundmentals of frequency and transient response. Transistor high - frequency