lecture 23 differential vs single ended

7/26/2019 Lecture 23 Differential vs Single Ended

1/16

EE105 Fall 2007 Lecture 23, Slide 1 Prof. Liu, UC Berkeley

Lecture 23

OUL!"E B# $i%ere&tial '()li*er+

co&t-d Ca+code di%ere&tial a()li*er+

Co((o&/(ode reectio&

$i%ere&tial )air it actie load

4eadi&6 Ca)ter 10./10.8.1

'""OU"CE9E"S 9idter( :2 re+ult+ u&derrad. +core+ o&ly6 ";73< mean=63< median=63.5< +td.de.;=.2

>ou (ay )ick u) your e?a( duri& a&y ' o@ceour. Regrade requests must be made before you leave

with your exam.

e li+t of (i+u&der+toodAforotte& )oi&t+ a+ ee&u)dated.

21446


2/16


Cascode i!erential "air

( )[ ]31331311 |||| rrrrrggRgA OOOmmoutmv +=

Half circuit for ac analysis

( ) 313313

313313

||||||)]||(1[

rrrrrgRrrrrrgR

OOOmout

OOOmout

+

++=


3/16


#elesco$ic Cascodei!erential "air

( )[ ] [ ])||(|||| 575531331 rrrgrrrggA OOmOOmmv



4/16

EE105 Fall 2007 Lecture 23, Slide Prof. Liu, UC Berkeley

%xam$le

[ ]( )opOOmmv

OOOmop

RrrrggA

R

rrr

R

rrgR

||)||(

2||||2||||1

31331

1575

1575

=

+

+=



5/16


%!ect o& 'inite #ail(m$edance

( )

EE

m

C

EE

m

C

CMin

CMout

Rg

R

Rg

R

V

V

21

2

1

2/

,

,

+

=

+

=

!f te tail curre&t +ource i+ &ot ideal, te& e& a& i&)utco((o&/(ode oltae i+ a))lied, te curre&t+ i& Q1 a&d Q2a&d e&ce te out)ut co((o&/(ode oltae ill ca&e.


6/16


%!ect o& (n$ut C) *oise(deal #ail Current

ere i+ &o e%ect of te i&)ut C9 &oi+e at te out)ut.


7/16


%!ect o& (n$ut C) *oise*on+(deal #ail Current

e +i&le/e&ded out)ut+ are corru)ted y te i&)ut C9 &oi+e.


8/16

EE105 Fall 2007 Lecture 23, Slide = Prof. Liu, UC Berkeley

Com$arison

e diferentialout)utoltae +i&al i+ te+a(e for ot ca+e+.

'or small in$ut C)noise, thedi!erential $air isnot a!ected.

Ideal Tail Current Non-Ideal Tail Current


9/16

EE105 Fall 2007 Lecture 23, Slide Prof. Liu, UC Berkeley

C) to ) Conversion-gainAC)+)

!f *&ite tail i()eda&ce a&d a+y((etry e.g.i& load re+i+ta&ce

are both)re+e&t, te& te di%ere&tial out)ut +i&al willco&tai&a )ortio& of te i&)ut co((o&/(ode +i&al.

( ) EEmC

CM

out

Rg

R

V

V

2/1 +

=

EE

m

CM

C

EEC

m

CEECBECM

Rg

V

I

RIg

IRIVV

21

22

+

=

+

=+=

( )

21

2

1

CCoutoutout

CCCout

CCout

RIVVV

RRIV

RIV

== +=

=


10/16


%xam$le

{ }3133131

||)]||(1[21

rRrrRg

g

RA

Om

m

CDMCM

+++

=


11/16


C944 i+ te ratio of te a&ted a()li*ed di%ere&tial

i&)ut +i&al to te u&a&ted co&erted i&)ut co((o&/(ode &oi+e tat a))ear+ at te out)ut.

Common+)ode ReectionRatio

DMCM

DM

A

ACMRR


12/16


i!erential to /ingle+%ndedConversion

9a&y circuit+ reDuire a di%ere&tial to +i&le/e&dedco&er+io&.

i+ to)oloy i+ &ot ery ood< it+ (o+t critical draacki+ +u))ly &oi+e corru)tio&, +i&ce &o co((o&/(odeca&cellatio& (eca&i+( e?i+t+. 'l+o, e lo+e alf of teoltae +i&al.


13/16


0 1 etter 1lternative

i+ circuit to)oloy )erfor(+ di%ere&tial to+i&le/e&ded co&er+io& it &o lo++ of ai&.

( )

,,

21

PNPoNPNom

inin

out rrgvv

v=


14/16


1ctive Load

it a curre&t (irror a+ te load, te +i&alcurre&t )roduced y Q1 ca& e re)licated o&to Q7.

i+ ty)e of load i+ di%ere&t fro( teco&e&tio&al +tatic loadG a&d i+ called a& actieload.G


15/16


i!erential "air with1ctive Load

e i&)ut di%ere&tial )air decrea+e+ te curre&t dra&

fro( RL y I, a&d te actie load )u+e+ a& e?tra Ii&to RLy curre&t (irror actio&< te+e e%ect+ e&a&ce eac oter.

i d i


16/16


1ctive Load vs. /taticLoad

e load i& te circuit o& te left re+)o&d+ to tei&)ut +i&al a&d e&a&ce+ te +i&le/e&ded out)ut,erea+ te load i& te circuit o& te rit doe+ &ot.

lecture 23 differential vs single ended

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