Automatic Analog Layout Generation

Design Environment: Mentor Graphics
Language: Perl
OS: Unix

An algorithm is developed for designing an automatic Op-amp layout generation by using scripting language. The layout of the two-stage Op-amp will automatically draw out in the Mentor Graphics IC station by inserting the essential data. The main challenges are design a common-centroid layout template, and how to route each transistor automatically without violating the DRC (Design Rule Check).

The algorithm invokes DRC file, using circuit netlist information to generate circuit layout automatically with a common-centroid layout template.

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Transistor Sizing Methodology for Low Noise Charge Sensitive Amplifier With Input Transistor Working in Moderate Inversion

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Good learning resources

1. Free lectures from top university professors

http://www.coursera.com

2. Free video lectures

http://www.freevideolectures.com

3. CMOS learning, by R. Jacob Baker

http://www.cmosedu.com

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http://www.uoguelph.ca/~sgregori/links.html

All about electronics information, resources, and companies

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IC Production Service

1. The MOSIS Service:

http://www.mosis.com

 

2. TSMC (Taiwan Semiconductor Manufacturing Company) :

http://www.tsmc.com/english/default.htm

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BSIM3 and BSIM4 MOSFET Models (Levels 47, 53, and 60)

Model type: nmos or pmos
These models are used in IC design. The set of instance parameters is the same as in level 1 MOSFETs.

3.6.23.1 BSIM3v2 (Level 47) MOSFET Model

Syntax:
M name (nodeDnodeGnodeSnodeB) model_name
+ param[=value]…
BSIM3v2 models have over 100 parameters. Most of these parameters are interesting only to engineers involved in the process of device characterization (i.e., extraction of BSIM3v2 model parameter values from experimental data). For details on this model consult [9, 3].
BSIM3v2 instances have the following properties that can be saved during simulation. See Table 3.62.
Table 3.62

BSIM3v2 MOSFET (level 47) properties calculated by the simulator
Name
Unit
Description
vbs
V
B–S voltage
vgs
V
G–S voltage
vds
V
D–S voltage
id
A
Drain current
gm
A∕V
Transconductance
gmbs
A∕V
B–S transconductance
gds
A∕V
D–S conductance
vth
V
Threshold voltage
vdsat
V
Saturation D–S voltage
BSIM3v2 instances have the same set of internal nodes and noise contributions as level 1 MOSFETs.

3.6.23.2 BSIM3v3 (Level 53) MOSFET Model

BSIM3v3 is a very popular MOSFET model for submicrometer IC design. Many different versions are available. The model version is chosen with the version model parameter. The following versions are available: 3.0, 3.1, 3.2, 3.2.2, 3.2.3, and 3.2.4. The latest version (3.2.4) is the default.
Example:
.model nm nmos (level=53 version=3.2.3…)
All level 1 instance parameters are supported, and the BSIM3v3 instances have some additional instance parameters available to the user. See Table 3.63.
The list of BSIM3v3 model parameters is very long. Interested readers can refer to [9, 3].
For BSIM3v3 models the simulator evaluates all properties that are evaluated for BSIM3v2 instances. Some additional properties are evaluated, too, as shown in Table 3.64.
Table 3.63

BSIM3v3 MOSFET (level 53) additional instance parameters
Name
Unit
Default
Description
nqsmod
0
Non-quasi-static (NQS) model selector (0..disabled, 1..enabled)
check
DEFINSTCHECK
Check instance parameters (1..yes, 0..no)
geo
0
Source/drain sharing selector (0..no sharing, 1..drain shared, 2..source shared, 3..drain and source shared)
Table 3.64

Additional BSIM3v3 MOSFET (level 53) properties calculated by the simulator
Name
Unit
Description
idrain
A
Drain current (absolute value in AC analysis)
idraincplx
A
Drain ac current (complex)
igate
A
Gate current (absolute value in AC analysis)
igatecplx
A
Gate ac current (complex)
isource
A
Source current (absolute value in AC analysis)
isourcecplx
A
Source ac current (complex)
ibulk
A
Bulk current (absolute value in AC analysis)
ibulkcplx
A
Bulk ac current (complex)
BSIM3v3 instances have the same internal nodes as level 1 MOSFETs. Also, an internal charge node named M name#charge is created when the instance parameter nqsmod is set to a nonzero value. The set of noise contributions is the same as for level 1 MOSFETs.

3.6.23.3 BSIM4 (Level 60) MOSFET Model

There are multiple versions of the BSIM4 model available. The choice of version is made by specifying the version model parameter. Possible values are 4.0, 4.1, 4.2, and 4.2.1. The default version is the latest one (4.2.1).
BSIM4 instances support all level 1 instance parameters, and additional parameters are supported, as shown in Table 3.65.
Table 3.65

BSIM4 MOSFET (level 60) additional instance parameters
Name
Unit
Default
Description
nf
1
Number of fingers
min
0
Minimize number of D or S diffusions for even-number fingered devices (1..yes)
rbdb
Ω
From model
Resistance between B and dbody internal node
rbsb
Ω
From model
Resistance between B and sbody internal node
rbpb
Ω
From model
Resistance between B and body internal node
rbps
Ω
From model
Resistance between sbody and body internal nodes
rbpd
Ω
From model
Resistance between dbody and body internal nodes
trnqsmod
From model
Transient NQS model selector (1..enabled)
acnqsmod
From model
AC NQS model selector (1..enabled)
rbodymod
From model
Distributed body R model selector (1..enabled)
rgatemod
From model
Gate resistance model selector (1..enabled)
geomod
From model
Geometry-dependent parasitics model selector (integer between 0 and 10)
rgeomod
0
S/D resistance and contact model selector (integer between 0 and 8)
BSIM4 models have many parameters. As these parameters as usually interesting only to process engineers, the list is omitted. Interested readers may refer to the BSIM4 manual available at [4] for details.
All quantities that are calculated for BSIM3v2 models are also calculated for BSIM4 models. Some additional quantities are also available (only in version 4.2.1). See Table 3.66.
Table 3.66

Additional BSIM4 MOSFET (level 60) instance properties calculated by the simulator
Name
Unit
Description
ibd
A
B–D current
ibs
A
B–S current
isub
A
Impact ionization substrate current
igidl
A
Gate-induced drain leakage current
igisl
A
Gate-induced source leakage current
igs
A
G–S diffusion region current
igd
A
G–D diffusion region current
igb
A
G–B tunneling current
igcs
A
Gate-channel source current
igcd
A
Gate-channel drain current
cgg
F
Gate capacitance
cgs
F
G–S overlap capacitance
cgd
F
G–D overlap capacitance
cbg
F
B–G capacitance
cbd
F
B–D capacitance
cbs
F
B–S capacitance
cdg
F
D–G overlap capacitance
cdd
F
Drain capacitance
cds
F
D–S capacitance
csg
F
S–G capacitance
csd
F
S–D capacitance
css
F
Source capacitance
cgb
F
G–B capacitance
cdb
F
D–B capacitance
csb
F
S–B capacitance
cbb
F
Bulk capacitance
capbd
F
Body-drain capacitance
capbs
F
Body-source capacitance
qg
As
Gate charge
qb
As
Bulk charge
qd
As
Drain charge
qs
As
Source charge
qinv
As
Inversion charge
Table 3.67

BSIM4 (level 60) MOSFET noise contributions
Postfix
Description
_rd
Drain series resistance thermal noise
_rs
Source series resistance thermal noise
_rg
Gate series resistance thermal noise
_rbps
sbodybody resistance thermal noise
_rbpd
dbodybody resistance thermal noise
_rbpb
B-body resistance thermal noise
_rbsb
B-sbody resistance thermal noise
_rbdb
B-dbody resistance thermal noise
_id
Drain current shot noise
_igs
G–S current shot noise
_igd
G–D current shot noise
_igb
G–B current shot noise
_1overf
Flicker noise
no postfix
Total MOSFET noise contribution
BSIM4 instances have several internal nodes. Nodes M name#drain and M name# source are used for connecting the drain and source series resistances. Nodes M name#gate and M name#midgate are created if the rgatemod instance parameter is set to a nonzero value. Nodes M name#dbody, M name#body, and M name#sbody are created if the rbodymod instance parameter is set to a nonzero value. Finally, internal node M name#charge is created if the instance parameter trnqsmod is set to a nonzero value. The noise contributions are shown in Table 3.67.
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Level 6 MOSFET Model

The level 6 model is a simplified MOSFET model developed at UC Berkeley. All level 1 model parameters are supported except kp, n, wd, xl, xw, delvto, bex, kf, and af. Some additional model parameters are also supported. See Table 3.61.
Table 3.61
Additional MOSFET level 6 model parameters
Name
Unit
Default
Description
kv
V
2
Saturation voltage factor
nv
0. 5
Saturation voltage coefficient
kc
A
5 ⋅10 − 5
Saturation current factor
nc
1
Saturation current coefficient
nvth
0. 5
Threshold voltage coefficient
ps
0
Saturation current modification parameter
gamma1
0
Bulk threshold parameter 1
sigma
0
Static feedback effect parameter
lambda0
1 ∕ V
lambda
Channel length modulation parameter 0
lambda1
1 ∕ V2
0
Channel length modulation parameter 1
The set of values calculated by the simulator and the set of internal nodes are the same as those in the level 2 model. Level 6 MOSFETs have no noise model and therefore no noise contributions.
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