258
Compact Models for Integrated Circuit Design
where:
C jbd is the unit-area bottom drain-body junction capacitance
C jbdsw is the unit-length drain-body junction sidewall capacitance along the
isolation edge
C jbdswg is the unit-length drain-body junction sidewall capacitance along the
gate edge
A deff and P deff , are the effective junction area and perimeter on the drainside of the source-drain diffusion, respectively
• C jbd is calculated by
C
CJD T
V
PBD T
V
CJD T
MJD
V
PBD
jbd
bs
MJD
bd
bs
=
⋅ −






<
⋅ +
−
( )
( )
;
( )
1
0
1
,
( ( )
,
T
V bd






≥







0
(6.112)
• C jbdsw is calculated by
C
CJSWD T
V
PB
D T
V
CJ WD T
jbdsw
bs
MJ
bd
=
⋅ −






<
⋅
−
( )
( )
,
;
( )
1
0
1
SW
S
SWD
+ +






≥







MJ
V
PBS
T
V
bs
bd
SWD
WD( )
,
0
(6.113)
• C jbdswg is calculated by
C
CJSWGD T
V
PBSWGD T
V
CJSWGD
jbdswg
bs
MJ
bd
=
⋅ −






<
−
( )
( )
;
1
0
SWGD
,
( ( )
( )
,
T
MJ
V
PBSWGD T
V
bs
bd
⋅ +






≥







1
0
SWGD
(6.114)
In the above model equations, the compact model parameters are represented by upper-case letters.
6.7 Summary
This chapter presented the dynamic MOSFET models for small signal analysis of MOSFETs in very-large-scale-integrated circuits using quasistatic
assumptions. MOSFET device capacitances are separated into intrinsic and