particle motion in the inversion layer nmos -- p type semiconductor – v gs > v t &...
TRANSCRIPT
Particle motion in the inversion layerG
S D+n+n
channel inversion layer
(electrons)x
y
z
L
GSE
ground
ground
NMOS -- p type semiconductor – VGS > VT & saturating VDS
DI
DSV
2
DSD n oxide GS TN DS
VWI C V V V
L 2
linear variation
NMOS -- p type semiconductor -- gate voltage VGS > VT – experimental
measurement of parameters (linear)
GV
G
S D+n+n
DI
D n oxide GS TN DSW
I C V V VL
DI
GSV
n oxide DSW
slope C VL
NMOS -- p type semiconductor – VGS > VT & saturating VDS
DI
DSV
2
DSD n oxide GS TN DS
VWI C V V V
L 2
DS GS TNV saturation V V
2GS TND n oxide
V VWI C
L 2
D
DS
dI0
dV n oxide GS TN DS
WC V V V
L
NMOS -- p type semiconductor -- gate voltage VGS > VT – experimental
measurement of parameters (saturation)
GV
G
S D+n+n
DI
2D n oxide GS TNW
I C V V2L
DI
GSV
n oxide GSW
slope C VL
Transient analysis
n nn
q nE qDn xq 0t x
njnq 0t x
D Sn n
0
V V q n nq n qD
L C x xnq 0t x
equation of continuity
conduction diffusion
electric field due to density inhomogeneity
Transient analysis
njnq 0t x
n n nn
j q nE qDx
G T D S0
x qn( x )V( x ) V V V V
L C
D S0
dV 1 q n( x )E V V
dx L C x
Transient analysisD S
n n0
V V q n nq n qD
L C x xnq 0t x
D Sn
2
n 20
n 2
V Vn nq qt L x
q nn
C x nqD 0
x x
Transient analysis
2
n 20D S
n n 2
q nn
C xV Vn n nq q qD 0t L x x x
n
x
NMOS -- p type semiconductor – normal biasing
this is normally
at ground potential
G
S D+n+n
B
source to substrate potential
must cause the PN junction
to be 0 or reverse biased.
Transconductance – non-saturation
Dm
GS
Ig
V
2
DSD n oxide GS T DS
VWI C V V V
L 2
m n oxide DSW
g C VL
Transconductance –saturation
Dm
GS
Ig
V
2GS TD n oxide
V VWI C
L 2
m n oxide GS TW
g C V VL
Electrical circuit model
groundS D
G
ground
in
m gsg V
dsC
gspC gdpCgsC gdC
drsr
+losses in n regionslosses in p region
dsr
gsTC gdTC
parasitic
gsp gdpC &C
Electrical circuit modeling a MOSFET
dsr
G D
S
dr
dsC'
m gsg V
sr
gdTC
gsTC
gsV
'gsV
Electrical circuit modeling a MOSFETlow-frequency
dsr
G D
S
dr
dsC'
m gsg V
sr
gdTC
gsTC
gsV
'gsV
1C
Electrical circuit modeling a MOSFETlow-frequency
G D
S
'm gsg V
gsV
'gsV
1C
dsr
Electrical circuit modeling a MOSFETlow-frequency
G D
S
'm gsg V
sr
gsV
'gsV
1C
gs gs m gs sV V ' ( g V ' )r
Electrical circuit modeling a MOSFEThigh frequency
dsr
G D
S
dr
dsC'
m gsg V
sr
gdTC
gsTC
gsV
'gsV
LR
Electrical circuit modeling a MOSFEThigh frequency
G D
S
'm gsg V
gdTC
gsTC
gsV
'gsV
LR
i gsT gs gdT gs dI j C V j C V V
dm gs gdT d gs
L
Vg V j C V V
R
Electrical circuit modeling a MOSFETgain
G D
S
'm gsg V
gdTC
gsTC
gsV
'gsV
LR
i gsT gs gdT gs dI j C V j C V V
dm gs gdT d gs
L
Vg V j C V V
R
dm gs gdT d gsL
i gsT gs gdT gs d
Vg V j C V VR
I j C V j C V V
Electrical circuit modeling a MOSFETgain
G D
S
'm gsg V
gdTC
gsTC
gsV
'gsV
LR
dm gs gdT d gsL
i gsT gs gdT gs d
Vg V j C V VR
I j C V j C V V
gsT MC C
Frequency limitations
GV
G
S D+n+n
sat
L
v
--
finite transit time
5
1 mm10 s
100 GHz
Ames
Simple three-dimensional unit cell
a
b
c