浙江大學(xué)電氣

模擬與數(shù)?；旌霞呻娐?/p>

，

2015-2016學(xué)年夏學(xué)期

2016年6月

Table3.1

Figure3.1illustratesasource-degeneratedcurrentsource.UsingTable3.1modelparameters,

Calculatetheoutput atthegivencurrentbias;

Calculatetheminimumoutputvoltagerequiredtokeepthedeviceinsaturation.

10uA

+

vOUT

-

2/1

VGG

100k

Solution:

rr

1

Figure3.1

1 2.5106

o ds2

2KWI

NLD

gm

ID

0.0410106

2110AV2210A

1

66.3AV

2FVSB

0.4

20.7112

mb m

g g 66.32

10.2AV

rout

rrds2

gm2

gmbs2

rds2

rgm2rds2

r= r

2K'WI

1

N

L DI

D

=2110

AV 10

2

2

1

A

1 100k

0.04V110A

=16.58×106Ω

orthemoreaccuratesolutioncanbederivedas

routrrds2gm2gmbs2rds2r

100K2.510666.310.22.5106100K

21.725106

WhileVDS≥VGS–VTHandVGS>VTH,MOSFETworksinsaturationregion.

ID

1KN'W

2 L

1011102

2

1

vDSMIN=VGS–VTH,

VGSVTH

0.3V

∴vOUTMIN=VGS-VTH+VS=0.3+100K×10uA=1.3V

10μA

iOUT

+

M4

M2

5/1 5/1

vOUT

M3

M1

5/1 5/1

-

Calculatetheoutput andtheminimumoutputvoltage,whilemaintainingalldevicesinsaturation,forthecircuitsshowninFigure3.2.AssumethatiOUTisactually10μA.UseTable3.1fordevicemodelinformation.

Figure3.2

Solution:

vout(min)

VGS3

VGS4

VT2

VGS3

VT4

VT2

2iD

2iD

210106

5110106

VGS3 0.891 1.082V

5uA

5uA

iOUT

+

M2

vOUT

M3

M1

-

DesignM3andM4ofFigure3.3(a)sothattheoutputcharacteristicsareidenticaltothecircuitshowninFigure3.3(b).ItisdesiredthatiOUTisideally10uA.

M4

10uA

10uA

i'

+

out

M2

4/1

v'

out

M3

4/1

M1

4/1

-

M4

1/1

Solution:

(a) (b)

Figure3.3

Forgetting

'

i

out

iout

10A

InFig.3.5a),

Thustoensure

i3i45A

iout10A

Wemusthave

W

L

W

2

L

1 3

W

L

3

1W

2L

1

142

21 1

InFig.3.5b)i4=i3=i1

W

V42WV121V424V12

L

L 1 1

4

1

V42

4

V12 1

V4 2V1

VG4VT2V1

VG2VG4VT2V1

VMIN2V1

AndwegetVMINinFig.3.5(a):

VMIN2V1

VG2VG4VT2V1

1

and

V42V1

InFig.3.5(a):

i4i3 i1

2

WV421WV12

L

4 2L1

W 1WV12

L4 2L1V4

V42 V12 1

V

For

1

4

V

4 4

W

L

4

1W

8L

1

141

81 2

AsthecircuitsshowninFigure3.4,IREF=0.3mAandγ=0.UsingthemodelparametersinTable3.1,

CalculatethevoltageVbwhenVX=VY;

IfVbis100mVsmallerthanthevaluein(a),calculatethedeviationofIoutfrom300μA.

VDD

iOUT

IREF

M2

X

40/0.5

Y

M1

M3

40/0.540/0.5

Vb

Figure3.4

Solution:a)

2IREF

KN'(W/L)1

20.3103

80110106

VGS1VT 0.7 0.961V

Vb2VGS11.922V

b)

(l0.5u)(l1u)

1u0.5u