Presto training course_1999

PRESTO 3.2 Training Course
Version 1.0 HDT proprietary
PRESTO 3.2
T
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Version 1.0
May 1999
The contents of this training course are proprietary data of High Design Technology. Use or
disclosure of the information contained in this document is allowed only under written
authorization of High Design Technology.
High
Design
Technology
Copyright 1998 High Design Technology.
All rights reserved.

PRESTO History
1988 Development starting
1990 SPRINT & SIGHTS High perfomance
simulation & modeling
1992 PRESTO Rel 1.1 Compliance analysis
1993 PRESTO Rel 1.2 + Crosstalk analysis
1994 PRESTO Rel 2.0 + SSN analysis + new GUI
1995 PRESTO Rel 2.1 + EmiR + THRIS integration
1996 PRESTO Rel 2.2 + EmiR-Cable + What-If Analysis
1997 PRESTO Rel 3.0 + ModEnv modeling+ IBIS interface
1998 PRESTO Rel 3.1 + Lossy lines and Modal method
1999 PRESTO Rel 3.2 + Net class propagation + New
error management
Introduction
i

PRESTO flow
Extract data
Setup libraries
Set simulation par.
Run simulation
View results
1
2
3
4
5
Introduction
ii

PRESTO
123456
789
FILE_TYPE=HDT_PLIB;
TIME=Thu Dec 10 10:45:33 1992
COMPONENT=AC04, 74AC04;
FAMILY=FACT;
PACKAGE=DEFAULT, DIP14, SOIC14;
FACTORY=DEFAULT;
TYPE=IC;
NPINS=14;
BEGIN_PIN
FACT_DR24_P=2,4,6,8,10,12;
FACT_RC_P=1,3,5,9,11,13;
FACT_GND_P=7;
FACT_VCC_P=14;
END_PIN;
BEGIN_FUNCTION
DRIVER=2,4,6,8,10,12;
RECEIVER=1,3,5,9,11,13;
POWER_FACT=14;
GROUND_FACT=7;
END_FUNCTION;
END.
Driver
Receiver
SSN report
Compliance
analysis
report
Overshoots
undershoots
rise and fall
time
report
Electrical models
Physical models
Board layout data
Introduction
iii
398.00 399.00 400.00 401.00 402.00 403.00 404.00404.40
TIME[nS]
-2.00 V
-1.75 V
-1.50 V
-1.25 V
-1.00 V
-0.75 V
-0.50 V
V(116)
70.00 80.00 90.00 100.00 110.00 120.00 130.00 140.00 150.00 160.00 170.00 180.00
-5.00V
-4.00V
-3.00V
-2.00V
-1.00V
0.00V
1.00V
2.00V
3.00V
4.00V
5.00V
6.00V
7.00V
8.00V
EMC
reports:Con
ducted and
radiated
emissions
What-If

Training course outline
• PRESTO important concepts
• CAD data extraction
• PRESTO input format
• Library Setup
• Special Nets
• Aliases setup
• Signal stimuli creation
• Signal mask creation
• Net class definition
• Simulation setup
• Running simulation
• Looking at simulation results
• Output waveform postprocessor
• Simulating crosstalk
• Simulating Simultaneous Switching Noise (SSN)
• Physical library
• Electrical library
• Performing What-If analysis (layout optimisation)
• Performing EMI analysis
1-1
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8
9
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18
19

PRESTO important concepts
• Design components
• Design nets
• Crossection
• Signal parameters
• Striplines
• Microstrips
• Reflections due to impedance mismatch
• Crosstalk noise
• Simultaneous Switching Noise (SSN)
• Physical models
• Electrical models
1-2

Design Components
Design components are physical devices of your design
(resistors, capacitors, integrated circuits, connectors, etc).
A component is characterized by:
– part name: specifies the type of device. This is the identifier
used to search components in libraries
– instance name: more than one component having the same part
name can be present in your design. The
instance name identifies univocally the
component.
– value: specifies the value of the component (if any). It is
used for resistors, inductors and capacitors.
– pins: a component has one or more pins where
design nets are connected
– package: it is the name of the component package.
Different packages can have different electrical
behaviors even if the part name is the same
1-3

Design nets
Design nets are physical interconnections (usually showing
low DC resistance) between two or more pins of components
implemented by metal traces.
– Net name is a name that identifies the entire net
– Special nets are power and ground nets
– Net segments are linear sections of the trace
– Vias are metalized through-holes used to connect net
segments belonging to different layers of the
crossection
– Bend a junction between two net segments defining a
corner
– T-junction a junction between three net segments
– Sub-net a subsection of a net composed by one or more
segments connecting two T-junctions or a
T-junction with a pin or two pins.
A net can also be implemented by a metal plane
1-4

Crossection
is the geometrical/physical description of the
transverse section of the board or MCM
y-direction traces
x-direction traces
metal plane
dielectric
1-5

Signal parameters
20%
80%
Overshoot
Undershoot
Rise edge
Fall edge
Overshoot
Undershoot
0%
100%
Rise time Fall time
1-6

Stripline and microstrip
dielectric1
metal plane metal plane
conductor conductor conductor conductor
dielectric2
metal plane
metal plane
dielectric3
conductor
dielectric1
dielectric2
dielectric1
metal plane metal plane
conductor conductor conductor conductor
dielectric2
air
conductor
dielectric1
air
microstrips
striplines
1-7
Examples of:

Signal reflections due to impedance
mismatch
Wave reflection occurs when the impedance at receiver or driver
ends is not matched to the characteristic impedance of the line.
In this case, a percentage of the incident wave is reflected back and
the same phenomenon happens at the other end of the line.
Reflections also occur when geometrical /physical discontinuities
affect the interconnection (vias, bends, changing of layer).
Due to the complexity of the interconnection topologies and the non-
linearities of drivers and receivers (V/I curve, clamping diodes), the
effects of reflections on signals can be pratically analysed only
through simulation.
1-8

Crosstalk
Crosstalk is a phenomenon that occurs when two or more traces
(usually belonging to different nets) follow parallel paths. In this
case, an edge travelling on one of the traces couples some of its
energy to the others, causing noise (far-end and near-end crosstalk).
Crosstalk depends on both electrical (signal edge shape) and
geometrical (coupling length and crossection) parameters.
The crossection of coupled structures is usually analyzed by means
of a 2-D electromagnetic field solver.
1-9
propagating edge
disturbing line
victim line
near-end crosstalk
far-end crosstalk

Simultaneous Switching Noise (SSN)
This phenomenon is due to current pulses caused by switching drivers.
The current pulses, flowing through lines or parasitic inductances, causes
an impulsive drop of voltage on the power supply rails. If several drivers
switch simultaneously, this voltage drop can exceed the noise margins of
nets at quiet state, causing undesired switching.
It is possible to distinguish two levels of SSN:
- Inside the component package: it is caused by the parasitic effects of the
power supply pins of the package. It is difficult to control.
- Outside the component package: it is caused by the non-ideal power
supply distribution on the board or MCM. It can be reduced by means of
decoupling capacitors.
1-10
PRESTO allows the simulation of both causes of SSN noise
allowing the verification of decoupling capacitors
effectiveness .

Physical Model
Describes:
– the pinout of the component package
– the function of the pin (driver, receiver, power supply, etc)
– the name of the electrical model to be utilized during the
simulation
1
2
3
4
5
6
7
8
9
FILE_TYPE=HDT_PLIB;
TIME=Thu Dec 10 10:45:33 1992
FAMILY=FACT;
FACTORY=DEFAULT;
TYPE=IC;
NPINS=14;
BEGIN_PIN
FACT_DR24_P=2,4,6,8,10,12;
FACT_RC_P=1,3,5,9,11,13;
FACT_GND_P=7;
FACT_VCC_P=14;
END_PIN;
BEGIN_FUNCTION
DRIVER=2,4,6,8,10,12;
RECEIVER=1,3,5,9,11,13;
POWER_FACT=14;
GROUND_FACT=7;
END_FUNCTION;
END.
1-11

Electrical Model
– models the electrical behavior of driver/receivers
– uses the Spice-like syntax of SPRINT simulator
– model parameters can be extracted from datasheets, Spice
simulations or measures (V/I curves or TDR)
Driver
Receiver
S_MODEL = RECEIVER;
DESCRIPTION = FACT receiver;
BEGIN_SUBCKT
*************** FACT RECEIVER MODEL ***********
* creation date: 19 Jan 1993
*
* maximum simulation time step: 100ps
* recommended simulation time step <= 50ps
* ideal logic output signal (0 1)
*********************************************
.SUBCKT FACT_RC 1 2 10 20
* in out VCC GND
E1 2 0 1 20 THR(2.5V 0 1)
RO 2 0 10MEG
CIN 1 0 4.5PF
PVCC 1 10 0V 0MA 0.55V 0MA 0.62V 0.1MA 0.74V 1MA 0.83V 5MA 0.87V 10MA
+ 0.9V 15MA 1V 40MA C=1P
PGND 1 20 -0.9V -50MA -.89V -20MA -.83V -10MA -.792V -5MA -.763V -2.5MA
+ -.731V -1MA -.69V -.3MA -.647V -.1MA -.6V -.02MA -.5V -.01MA 0 0 C=1P
.ENDS FACT_RC
*********************
END_SUBCKT
1-12

CAD data extraction
2-1
• Library Setup
• Special Nets
• Aliases setup
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19

CAD data extraction (1)
1. Execute extract command from the PRESTO user
interface: Run->CAD Extractor
2. Locate the CAD files that have to be processed:
the extractor will store the PRESTO files in the
current working directory
CAD data extraction
2-2
.pnf file
.pgf file
.pxf file
.psf file

CAD data extraction (2)
• Supported CAD format are:
– ALLEGRO (Cadence)
– BOARDSTATION (Mentor)
– SPECCTRA (CCT)
– VISULA (Zuken)
– THEDA (Incases)
– PADS (Pads Software)
– P-CAD (ACCEL Technologies)
• For further details please refer to the PRESTO User
Manual
CAD data extraction
2-3

PRESTO input format
3-1
• Library Setup
• Special Nets
• Aliases setup
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19

PRESTO input format
• PRESTO input format is composed by four files:
– PRESTO Netlist File (design.pnf)
– PRESTO Geometric File (design.pgf)
– PRESTO Crossection File (design.pxf)
– PRESTO Copper Areas (design.psf)
PRESTO input format
3-2

PRESTO Netlist File (.PNF)
• Describes the component list and attributes
• Describes the net list and attributes
DEFAULTS
UNITS_PER_INCH = 1000;
END_DEFAULTS
SUMMARY
NUM_NETS = 22;
NUM_COMPONENTS = 17;
NUM_CONDUCTORS = 6;
END_SUMMARY
COMPONENTS
IC23 = 74AC04-2, PKG = SOIC14, XCMP = 6300, YCMP = 5400;
U4 = L20-1, PKG = DIP24_4, XCMP = 3200, YCMP = 6600;
.............
NET_DESCRIPTION
RESETN = IC24 1, U4 5;
RESET = IC24 2, U7 5;
............
END_NET_DESCRIPTION
END_BOARD
user unit declaration
design summary
component description
net connectivity description
PRESTO input format
3-3

PRESTO Netlist File (2)
Some attributes of the component list can be
modified by the user:
• Choose Part Editor from Run
menu
• You can assign an alternate name
for both the part name and
package name to be utilized
during the search procedure in
library
• You can assign/modify the value
property of passive components
(R,L,C). Usually this parameter is
automatically extracted from the
CAD interface.
PRESTO input format
3-4
Note: To address names in library, it is suggested to use the ALIAS definition (see later) instead of
Alt.name and Alt.pack. Infact ALIAS definitions doesn’t change if a new CAD extraction is done.

PRESTO Geometric File (.PGF)
• Describes the physical topology of the nets
P_D: 37, 75, 80, 95;
V_D: 75;
WDH: 12, 50, 100;
NET: RESETN;
SEG: 0, 0, 5225, 5550, 5600, 5550;
VIA: 0, 5225, 5550;
CMP: IC24, 1, 0, 100000, 5600, 5550;
SEG: 0, 3, 5225, 5550, 3750, 5550;
SEG: 0, 3, 3750, 5550, 3675, 5625;
SEG: 0, 3, 3675, 5625, 3675, 6150;
SEG: 0, 3, 3675, 6150, 3575, 6150;
SEG: 0, 3, 3575, 6150, 3525, 6200;
SEG: 0, 3, 3525, 6200, 3200, 6200;
CMP: U4, 5, 1, 111111, 3200, 6200;
NET: RESET;
SEG: 0, 0, 5600, 5500, 5675, 5500;
SEG: 0, 0, 5675, 5500, 5700, 5525;
SEG: 0, 0, 5700, 5525, 5700, 6150;
types of pads
via diameters
trace widths
net name
net description in term of
vias, pads and segments
PRESTO input format
3-5

PRESTO Crossection File (.PXF)
• Describes the transverse section of the board or
MCM substrate
INS: AIR,0,,1,0,0;
CND: COPPER,1.44,TOP,595900,1,0;
INS: FR-4,9.84252,,4.7,2,1;
SHL: COPPER,1.44,VEE,595900,3,1;
INS: FR-4,12,,4.7,4,2;
CND: COPPER,1.44,S1,595900,5,2;
INS: FR-4,12,,4.7,6,3;
CND: COPPER,1.44,S2,595900,7,3;
INS: FR-4,12,,4.7,8,4;
SHL: COPPER,1.44,GND,595900,9,4;
INS: FR-4,9.84252,,4.7,10,5;
CND: COPPER,1.44,BOTTOM,595900,11,5;
INS: AIR,0,,1,12,6;
conductor layer declaration
insulator layer declaration
shield layer declaration
(filled or grid metal plane)
Note: Some parameters of the crossection
(dielectric constant, layer thickness, etc) can be
modified. In this way it is possible to perform
WHAT IF analysis, running multiple simulations
with different parameters
PRESTO input format
3-6

PRESTO Copper Areas File (.PSF)
• Describes the copper areas of the board like
power planes, partial or splitted metallization and
so on.
3-7
Note:
Metal planes will be managed as a grid of lossy
transmission lines in Q2/99
PRESTO input format

Library Setup
4-1
• Library Setup
• Special Nets
• Aliases setup
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19

Library setup
• Libraries (both physical and electrical) are organized in a database to insure a
fast search of models
• System libraries are shipped with the software and cannot be modified
• More than one electrical/physical library can be open at the same time
• Two additional levels (other than System library level) can be used to define
libraries: User level or Group level.
system libraries paths
user/group physical libraries list
user/group electrical libraries list
Library Setup
4-2

Library priority
• During the model link phase, PRESTO begins the search of model
description starting from the user libraries sorted in the same
order they are listed in the window and then in the group and
system libraries respectively, if models are not found in lower
level libraries.
• The Library Setup window (available within the Setup menu)
allows the user to add library paths, delete them or change the
priority.
Note: It is suggested to use group level libraries to define models or library
aliases that have general meaning inside a group of designers. For example,
the Group level library could contain the standard components available in
warehouse, while the user level libraries could be used to define aliases
or/and to contain models of semicustom ICs (design specific components).
Library Setup
4-3

Special nets
5-1
• Library Setup
• Special Nets
• Aliases setup
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19

Special Nets
• Special nets are power and ground nets
• Special nets can be:
– distributed: wired power supply nets (implemented by metal
traces) are translated into transmission line equivalents as well
as other nets.
– collapsed: the power supply net distribution is collapsed in
one single electrical node. Metal planes of power supply are
automatically collapsed.
• Special nets require a voltage value assigned
Special nets
5-2

Special net identification
• A net can be specified as Special in two ways:
– if the power supply net name is already known, you can setup
directly this property by means of the commands available in
the Net Editor window (available within the Test Control menu)
– The command Search Special Net is available in the Net Editor
window: it uses the information stored in the physical libraries
to identify nets that connect power and ground pins of
components
Note: The voltage value associated to the special net must always be
specified by the user before running the simulation
Special nets
5-3

Special net management
During the simulation, the special nets are connected to electrical
models of power supply:
• If the special net is collapsed in a single electrical node, the power
supply model is connected to the node
• If the special net is distributed, the power supply model(s) is(are)
connected in the network in correspondence of component pins
with the property TYPE=GENPOWER (see physical models
properties). If no pins have attribute GENPOWER, the special net
is automatically turned to collapsed type
Note: The power supply model is a two pin electrical model (the second pin is
ground) and must be available in the electrical library . It can be described as an
ideal power supply (ideal independent voltage generator) or can include
parasitic effects as noise (ripple, burst, non-linear output resistance)
Special nets
5-4

Aliases setup
6-1
• Library Setup
• Special Nets
• Aliases setup
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19

Aliases
Aliases define equivalencies between two names of components or
packages
• Different CAD environments can utilize different names for the same
component (for example: DIP14, DIP14_4, DIP14CA)
• Different manufacturers can identify their components with a
specific prefix/suffix (for example: 74AC08, SN74AC08)
• Designers sometimes utilize internal codes to identify component or
package names (for example warehouse codes)
Aliases are used by PRESTO to identify a component of the library having a part
name that is not equal to the part name specified in the design netlist (.pnf file).
The same applies for package names.
Aliases setup
6-2

Aliases type
• Library aliases
– can be defined for component names only. The alias definition
(netlist part name pointing to a library part name) is inserted in
the same physical library where the pointed part name is
stored
• Design aliases
– can be defined for component or package names. The alias
definition is stored in a specific file (.ali) within the current
directory and its validity is limited to the current design.
Aliases setup
6-3

Library aliases
• Library aliases are stored in the same library of the pointed
physical model.
• From a user point of view, it is equivalent to create a new physical
description of the component with a different name.
• Library aliases cannot point to another alias definition.
• Library aliases can be used from many designers at the same time
(it is only necessary to link the physical library).
Part or package name of the
component in netlist
component in library
Design aliases menu is activated
through the command Alias
Manager-> Library Aliases available
within the Model menu
Aliases setup
6-4

Design aliases
• Design aliases can have only local meaning (current design)
• PRESTO first replaces the names specified in the netlist with the
names pointed by the design aliases (creating a new key to access
the physical library) and then starts the search in library
component in netlist
component in library
Design aliases menu is activated
through the command Alias
Manager-> Design Aliases from the
Model menu
Aliases setup
6-5

7-1
Signal stimuli creation
• Library Setup
• Special Nets
• Aliases setup
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19

Used to specify the switching time features of drivers during the
simulation. A stimulus is characterized by:
– stimulus name (for example: stim1)
– binary bit sequence (for example: 10010110111)
– working bit rate expressed in Mbit/s (for example: 150)
The time of the single bit is
calculated as:
tbit (ns) =
1000
bit-rate (in Mbit/s) tbit
7-2

Stimuli Setup
Stimulus bit-sequence can be specified
directly or can be contained in an ASCII
file
it is possible to delete, modify or
create a new stimulus declaration
using the commands of the Stimulus
menu
Note: If the simulation time window is
longer than the stimulus duration, the bit-
sequence will be automatically repeated.
7-3

Stimuli LAB
• create the following stimuli declarations:
– a 50 MHz clock with 50% duty-cycle
– a 10 Mbit/s stimulus with bit-sequence 1011011
– a 20 Mbit/s stimulus with bit-sequence 110110101 specified in a
file called filestim
– a 100 MHz clock with 20% duty cycle
7-4

Signal mask creation
8-1
• Library Setup
• Special Nets
• Aliases setup
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19

• Compliance analysis of signal is performed with
respect to user-defined masks.
Possible shapes:
– Uniform masks
– PWL masks
(Piece-Wise Linear)
• Masks are defined with respect to a reference
signal
• Signals violating the masks during the simulation
are reported in the .rep file
8-2

Uniform masks
• These masks are well suited to check noise
amplitude on signals at fixed voltage values
(power supply nets or victim nets during a SSN or
crosstalk analysis)
• The signal voltage used as reference is specified
in the net class definition.
• Only two noise margins (lower and upper) have to
be defined
Upper Margin
Lower Margin
Reference value
8-3
added noise

PWL masks
• PWL masks are suitable to check integrity of
switching signals
• PWL masks behaviors can be defined graphically
by 4 shapes:
– Rising Upper edge (RU)
– Rising Lower edge (RL)
– Falling Upper edge (FU)
– Falling Lower edge (FL)
• PWL masks are defined:
– by %
– by value
• It is always necessary to specify a maximum
operating frequency
RL mask
RU mask
FU mask
FL mask
A
B
C
D
E
F
G
H
reference
y
t
bit-time bit-time
8-4

PWL mask defined by %
• The maximum working frequency specification is necessary to
draw the mask shapes
• The reference signal ranges always between 0 and 1 (0-100%)
• In the net class definition (where the mask will be used) the user
has to set the actual reference signal swing: the mask amplitude
will be automatically scaled
These masks can be utilized for more than one net class declaration, because
their shape applies to whatever signal swing.
reference
y
t
0%
100%
y
t
V2
V1
net class definition:
High_value = V1
Low_value = V2
as you define it as PRESTO actually simulates it
8-5

PWL mask defined by value
• The maximum working frequency specification is necessary to
draw the mask shapes
• The reference signal swing is user-defined
• The net class definition utilizing a PWL mask defined by value will
set the actual reference signal swing to the value specified in the
mask: the mask amplitude will not be scaled in this case
These masks can be utilized to check signals with well specified noise
tolerances.
y
t
V2
V1
net class definition:
swing value are
defined by the mask
as you define it as PRESTO actually simulates it
y
t
V2
V1
8-6

Mask shape definition (1)
Mask name
maximum working frequency: a
mask can be used to check signals
switching at a bit rate lower or equal
to the maximum working frequency
click here to start the shapes creation of a
new mask
click on these buttons to modify a
specific mask shape
By % or By value selection
8-7

Mask shape definition (2)
As example, the procedure to create a RU shape is shown:
0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.00
TIME[nS]
-1.00 V
-0.50 V
0.00 V
0.50 V
1.00 V
1.50 V
2.00 V
0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.00
TIME[nS]
-1.00 V
-0.50 V
0.00 V
0.50 V
1.00 V
1.50 V
2.00 V
0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.00
TIME[nS]
-1.00 V
-0.50 V
0.00 V
0.50 V
1.00 V
1.50 V
2.00 V
1) The reference rising
waveform will be displayed:
the marker of the starting point
is forced to move only on the Y
axis.
2) A mask segment is defined by
positioning the marker on the
chosen point and by pressing the
left button of the mouse; now the
marker can only move at the right
of the selected point and a
hairline will connect the marker
with this point.
3) This procedure is repeated
during the selection of the
other breakpoints. The total
number of breakpoints can
range between 3 and 20. After
choosing the last point, click
on the right button of the
mouse to exit.
8-8

Masks LAB
create the following Mask definitions:
– a uniform mask to check 5V power supply signals with 5%
tolerances
– a PWL mask by percentage with:
» max working frequency = 10Mbit/s
» noise tolerances on steady state values = 10% swing
» noise tolerances for overshoots = 20% swing
» other parameters are free
– a PWL mask by value for CMOS signals with:
» max working frequency = 20Mbit/s
» noise tolerances = 1.25V (reference signal= 0-5V)
» max delay allowed = 3ns
8-9

Net class definition
9-1
• Library Setup
• Special Nets
• Aliases setup
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19

Net Class definition
A Net Class defines a set of parameters that will be utilized to
check signals during the simulation:
– the stimulus assigned to the driver
– the mask used to check the signal
– the reference values used to scale and shift uniform or PWL signal masks
– the delay time of the stimulus before starting the signal checks (to allow the
setup of the start-up transient)
t
stimulus td
t
mask generator
net driver
net under analysis
rec. 1
rec. 2
rec. n
mask violation
t
V2
V1
1
0
1
0
RESULTS
checker
td
WARNING:
The working frequency of the
used stimulus within a net
class definition cannot
exceed the maximum working
frequency of the signal mask.
9-2

Net Classes application
• to check quiet nets (like power supply nets, victim
nets during a xtalk or SSN analysis)
– the mask type is Uniform
– the first bit of the stimulus assigned to the class specifies the
steady state level for victim nets (it has no meaning for power
supply nets)
»01101101 “0” logic state
»11101100 “1” logic state
• to check switching nets
– the mask type is PWL (by % or by value)
– the bit sequence is applied to the driver as specified by the
stimulus definition
9-3

Net Class reference values
• for Uniform masks, the two values have to be identical and specify
the absolute voltage value to be applied to check noise amplitude on
quiet nets .
• for PWL by % masks, the two values are used to scale the mask
parameters (amplitude only) during the simulation.
• for PWL by value masks, the two values are automatically set to the
masks reference signal values.
reference values
9-4

Simulation setup
10-1
• Library Setup
• Special Nets
• Aliases setup
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19

Simulation setup
1) set library paths and aliases
2) Identify power supply nets and set their voltage values
3) assign class to nets
4) set simulation parameters
Before running a simulation follow these steps:
Simulation setup
10-2

Set library paths and aliases
• System libraries are automatically set by means of the
environment variable HDTTOOLS
• Physical and electrical libraries must be selected by the
user through the Library Setup window.
• Aliases (both library and design) must be specified. If
all components already have the right name in library,
the alias setup is not required.
If one or more components are not identified during the
simulation, an error occurs:
“Error: physical models missing in library”
Simulation setup
10-3

Identifying missing components
If some components are missing in library, the .log file
will report their names:
part-name, package name
and factory as specified
in the netlist
part-name, package name and factory
name used to search in library (design
aliases are applied before the search
starts)
component that has been found in library:
component that has not been identified:
“Component 100125-1 PDIL24_4 Default found as 100125 DIP24 Default in library mylib.plb”
“Warning: Component 100124-1 PDIL24_4 Default searched as 100124-1 DIP24 Default not Found!”
library name
Possible actions:
• create a physical description of the component or
• define an alias or
• utilize the default model facility.
Simulation setup
10-4

Default model facility
If some components are not described in library,a list of their pins is
created. You can assign default I/O driver or receiver models (TTL,
CMOS, ECL, Low voltage) to each pin of the missing component list
using the Default Model Editor window without the definition of a new
specific physical model.
Note: Remember to set the
“Default Models”button in the
Simulation Setup window before
running the simulation again
Simulation setup
10-5

Special nets
Special nets can be identified by the user or by
means of the “Search Special Nets” command
available on the Net Selector window.
This command utilizes the information contained in the physical
library to identify the nets connected to power and ground pins of
components. In order to work properly, it is required to set the
libraries paths before running the Search Special Nets command.
In any case, you must specify the voltage
value and the collapsed/distributed property
for each special net.
Simulation setup
10-6

Net Class assignment
• A Net Class specifies the type of analysis to perform on the net.
• Any net must have a net class assigned before running the
simulation.
• A default class is automatically set for the nets without a specific
class assigned by the user.
• A class can be assigned:
– by the user using the Net Editor window;
– automatically using the command “Automatic Net Class Assignment”
available under the Nets Attributes menu of the Net Selector window. In
this case, the default net classes associated to the drivers in the
physical libraries will be assigned to the nets. In order to work properly,
it is required to set the libraries paths before running the Automatic Net
Class Assignment command.
Simulation setup
10-7

Basic simulation parameters setup
Specify the use of default models for
components not available in library
Xtalk, SSN switches: enable these two
types of analysis
Resolution of the graphical output waveforms: 300-1000 samples give a good
resolution in normal situations. This number must be increased to maintain a
good resolution in case of zoom or eye-diagram plots. In this case the output
file can be very large.
Simulation time step: a value between 10 and 100
(ps) is suggested for normal situations
The simulation time window can be automatically
evaluated on the basis of the lengths of the bit-
sequences assigned as stimuli to the drivers or can
be selected by the user
Simulation setup
10-8
Enable the simulation of
the modifications made
with the What-If tool

Running simulation
11-1
• Library Setup
• Special Nets
• Aliases setup
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19

Running the simulation
To start the simulation choose the command Run Simulation from
the Run menu.
– phase 1:
» translates the physical data of layout traces into transmission lines,
» checks that all physical models are included in library,
» calls the EM field solver if crosstalk analysis is activated
– phase 2:
» imports in the netlist the electrical models (with its right package model),
» sets simulation parameters
– phase 3:
» SPRINT executes the transient simulation of the design,
» produces the output file
Errors are stored in the prerr.err file (simulation phase) and
uierr.err (user interface). Messages and warnings are stored in the .log file.
Running simulation
11-2

Looking at simulation results
12-1
• Library Setup
• Special Nets
• Aliases setup
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19

• Compliance analysis ASCII report file
• Graphical analysis with SIGHTS
– plot, mplot, plot_by_net, etc
– eye diagram (for Unix-based workstations only)
12-2

Compliance analysis report file
** COMPLIANCE ANALYSIS REPORT **
Design name: tutorial
Net name Upper mask Lower mask I ntegrated Violation
Violation Violation Error
------------------------------------------------------------------------------------------------
VCC * 10.972890
RESET * 1.485747
DATA * 1.484746
RESETN * 1.483746
------------------------------------------------------------------------------------------------
DATA1 * 1.483746
PULLUP * 1.060050
PULLDOWN * 0.705617
FANIN * 0.390969
------------------------------------------------------------------------------------------------
VEE
OUTECLP1
GND
OUTECLM1
• Lists the nets not passing the
compliance analysis test (masks
violations).
• The check is performed on
receiver pins only.
• The file reports the mask that has
been violated (upper or lower) and
prints a number representing the
total integrated violation error
12-3

Graphical analysis
• Waveforms can be displayed with SIGHTS
• Activated by the command: View->results->Graphical it
allows the plotting of waveforms
• The following description refers only to particular
functions of SIGHTS suitable for S.I. Analysis
• For Unix based workstation there is an other old
(no XVT based) version of Sights (Run->Sights)
that allows a larger number of functionality. For a
general description please refers to “SIGHTS User
Manual
12-4

Waveforms can be referred by component/pin_name or by the
net_name they belonging. The related netclass masks can be
added to the display. Background can be white or black. An
“EVAL” function that allows you to display waveform values is
available.
70.00 80.00 90.00 100.00 110.00 120.00 130.00 140.00 150.00 160.00 170.00 180.00
TIME[nS]
-5.00V
-4.00V
-3.00V
-2.00V
-1.00V
0.00V
1.00V
2.00V
3.00V
4.00V
5.00V
6.00V
7.00V
8.00V
#U4_1
#MASKdefaultcmos_L
#MASKdefaultcmos_U
#IC23_4
Plot and Plot by net (new Sights)
12-5

Plot and Plot by net (old Sights)
Single waveforms can be plotted with the command:
“Plot <testpoint list>“.
The command Plot by net (“Plot -n <netname list>“) plots all the
testpoints of a net with the related masks
70.00 80.00 90.00 100.00 110.00 120.00 130.00 140.00 150.00 160.00 170.00 180.00
TIME[nS]
-5.00V
-4.00V
-3.00V
-2.00V
-1.00V
0.00V
1.00V
2.00V
3.00V
4.00V
5.00V
6.00V
7.00V
8.00V
#U4_1
#MASKdefaultcmos_L
#MASKdefaultcmos_U
#IC23_4
12-5bis

Eye diagrams (old Sights only)
Eye diagrams are obtained by superimposing all the time frames
of a bit sequence. This function is very useful to check jitter and
intersymbol interference. Usually, this function requires the
definition of stimulus signals with long bit-sequences.
398.00 399.00 400.00 401.00 402.00 403.00 404.00404.40
TIME[nS]
-2.00 V
-1.75 V
-1.50 V
-1.25 V
-1.00 V
-0.75 V
-0.50 V
V(116)
12-6

Other useful functionalities of SIGHTS
(Old Unix version only)• Multiplot
Plots each waveform in a dedicated section of the graphic window
• Scanplot
Plots sequentially all the waveforms of the graphic file net by net
• XY Plot
Can use the samples of a waveform as X-axis
• Waveform cursors
Displays the numeric values of the waveform through a couple of cursors
• Zoom
Enlarges sections of the graphic window
• Piece-Wise Linear (PWL) extraction
A set of selected samples can be extracted from a waveform and saved on a PWL file
• Measurement instrument interfaces
Allows the acquisition of measured waveforms (DSO, TDR) to be compared with simulations or
used to build up behavioral models through PWL extraction.
• Mathematical functions
All typical mathematical operations can be performed on waveform samples
12-7

Output waveform postprocessor
13-1
• Library Setup
• Special Nets
• Aliases setup
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19

Output waveform postprocessor (1)
Overshoots, undershoots, rise and fall times can be
extracted from the graphical output file
Design: xxxxxxxx
Number of samples: 1000
Time Step: 2.6e-10
--------------------------------------------------------------------------------
Net: /A(1) Class: defaultcmos
Part Pin Rise Fall Rising Rising Falling Falling
Time Time Edge Edge Edge Edge
Ovsh Udsh Ovsh Udsh
(ns) (ns) (V) (V) (V) (V)
IC6 5 8.190 5.704 5.396 4.904 -0.459 0.402
IC9 9 8.219 5.675 5.417 4.850 -0.447 0.410
IC3 9 10.042 7.299 5.510 4.743 -0.436 0.452
IC6 9 8.141 5.637 5.407 4.897 -0.463 0.408
IC2 1 8.561 5.976 5.353 4.861 -0.431 0.419
--------------------------------------------------------------------------------
All the testpoints parameters can be
displayed or filtered in order to store
only the testpoints that violate the user-
defined value.
13-2

1) Run the simulation with graphic output as option
2) Set the parameters in the Wave postprocessor
window
3) Click on Run
4) View result
Output waveform postprocessor (2)
13-3

Pin-to-Pin delay
• Activated by View->Delay Report
• Evaluates the propagation delay between the driver and the receivers.
• Four values are given: two for the rise edge and two for fall edge.
• For each edge the maximum/minimum delay are evaluated (related to
Vil and Vih threshold crossing)
13-4
Vil
Vih
VOmin
VOmax
Threshold
unloaded driver
loaded driver
receiver
tdd
tdmin
tdmax
tdm
driver stimulus

Simulating crosstalk
14-1
• Library Setup
• Special Nets
• Aliases setup
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19

• Check for noise between two or more parallel
traces (coupled lines)
• Coupled lines can belong to different layers
• Crosstalk simulation can be added to SSN
analysis
• Compliance checks can be performed on signals
affected by crosstalk noise
• Losses can be taken into account
14-2

Crosstalk analysis flow
1 2 3
10 20 30
1
2
3
10
20
30
1
2
3
10
20
30
unbalanced TL
balanced TL
1
2
20
t
t
t
• Coupled structures are identified
scanning the design using geometrical
filters specified by the user
• Coupled structures are composed by
parallel traces with any orientation.
• Up to 32 parallel traces can be simulated
for each layer. Up to 4 layers (between
two metal planes) can be taken into
account simultaneously.
• The EM field solver (PREFIS) evaluates
the coupling parameters.
• A transmission line model based on Marx
method (striplines) or modal method
(microstrips) is created and included in
the netlist.
• The victim net is selected.
• The simulation is performed
14-3

Extracting coupled structures
• Coupled structures are extracted by means of an exhaustive
geometrical analysis of the routing. Three parameters can be
specified:
– mininum length: specifies the minimum length of a coupled segment to
consider during the search
– maximum distance: specifies the maximum distance between two parallel
segments to consider during the search
– resolution: is the minimum length of a coupled section to be considered
significant during a crosstalk simulation
14-4

Crosstalk structures
Min Length = 50 mm MaxDistance = 2 mm Resolution = 5 mm
PARAMETERS SETUP:
8015
20
4 4
Net 5
Net 1Net 2
Net 3
Net 4
xtk1xtk2
xtk3
Primary structure
(length > Min Length)
Secondary structure
(length < Min Length
length > Resolution)
Discarded structure
(lenght < Resolution)
• A primary structure is a coupled section of length > Min Length.
• A secondary structure is a coupled section of length < Min Length that is the
continuation of a primary structure or other secondary structures.
• All secondary structures of length < Resolution are discarded.
• A structure can be neglected be the user (Action->Delete Xtalk)
14-5

Victim nets
• Optionally, during the analysis, a selected net (victim net) is held at
quiet state while the others (disturbing nets) switches. This can be
specified for each structure of the list in two ways:
– one by one manually
– automatically by the program (the selected net is in the middle of the structure)
• The quiet state can be a logic “0” or “1” depending on the net class
assigned to the victim net.
victim net
selection. NONE
selection means
no victim net (to
be used for
differential
pairs)
net class
assigned to the
victim net
(NONE for
differential
pairs
14-6

Electromagnetic Field Solver
• The PRESTO electromagnetic field solver (PREFIS)
utilizes the method of moments and returns the LC
matrices of the coupled structures.
• Each Stripline structure (with homogeneous dielectric)
is then converted in a transmission line equivalent
subcircuit by means of the Marx method.
• Each Microstrip structure is then converted in an
equivalent subcircuit by means of the multimodal
decomposition.
• The structures analyzed are stored in a special database
(one for each design) and are available for further
simulations to skip further calculations.
14-7

Running crosstalk analysis
• Run the Crosstalk Preprocessor with the
specified geometrical filters
• Choose the victim nets and assign net classes to
them (optional)
• Set Xtalk analysis button in Setup Simulation
menu
• Run the simulation
14-8
Note: the user is allowed to not assign the victims during the crosstalk analysis. In
this case the models of the interconnections will take in to account the crosstalk, but
all the signals will be switching. This can be useful, for example, when a couple of
balanced differential lines are analyzed.

Crosstalk analysis results
• Results can be obtained in ASCII or graphical
way, according to the setup of the simulation
setup menu
– if the setup is ASCII: the results are available in the .rep file as
masks violation reports
– if the setup is graphical: the results can be displayed with
SIGHTS as waveforms
t
14-9

Simulating SSN
15-1
• Library Setup
• Special Nets
• Aliases setup
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19

SSN analysis
• Check for noise caused by drivers switching
simultaneously.
• Noise affects both drivers held at quiet state and
receivers thresholds.
• SSN macromodels are automatically built up by
means of the physical model descriptions.
• SSN analysis is fully compatible with crosstalk
checks.
SimulatingSimulating SSN
15-2

SSN analysis flow
t
t
t
• SSN macromodels of ICs are built up
automatically starting from library model
description.
• A common package model is
automatically inserted into the IC model.
(RLC, Transmission Line or S-parameters
models are allowed)
• Switching drivers are connected to their
actual interconnection topologies.
• Quiet drivers are set to “0” or “1” logic
level.
• The noise caused by the switching outputs
affects also the behavior of the clamping
diodes of receivers belonging to the same
package.
• Clamping diode currents of receivers
affect the behavior of other
drivers/receivers belonging to the same
package.
1 2 3456
7
8 9
FILE_TYPE=HDT_PLIB;
TIME=Thu Dec 10 10:45:33 1992
FAMILY=FACT;
FACTORY=DEFAULT;
TYPE=IC;
NPINS=14;
BEGIN_PIN
FACT_DR24_P=2,4,6,8,10,12;
FACT_RC_P=1,3,5,9,11,13;
FACT_GND_P=7;
FACT_VCC_P=14;
END_PIN;
BEGIN_FUNCTION
DRIVER=2,4,6,8,10,12;
RECEIVER=1,3,5,9,11,13;
POWER_FACT=14;
GROUND_FACT=7;
END_FUNCTION;
END.
gnd1 package pins
power1 package pins power2 package pins
input output
on-chip
power1 net
on-chip gnd1 net
on-chip
power2 net
on-chip gnd2 net
gnd2 package pins
... ...
......
supply pin models
supply pin models
modelsmodels
Simulating SSN
15-3

Percentage of switching drivers (1)
How many drivers switch
simultaneously for each
component?
This number is usually very difficult to set in case of large
components:
• for simple components (e.g. AC244) the assumption is very easy: the worst case is
obtained with all drivers switching except one that is set at quiet state.
• for complex components having, for example, more than one output bus, the actual
timing of the design becomes very important and the percentage of switching drivers
is different for each component. Normally, the previous rule (all drivers are switching
except one) cannot be applied, because the number of power pins of large
components is usually not designed on the basis of all driver switching assumption:
This hypothesis can be too pessimistic.
Simulating SSN
15-4

Percentage of switching drivers (2)
PRESTO allows two approaches:
a) rough simulation:
a fixed percentage of switching drivers is assigned to component packages
b) accurate simulation:
1) select a time window on a logic simulation already performed on the design.
2) utilize the bit sequences obtained as output of the logic simulation to set
PRESTO signal stimuli and related net classes.
3) assign the classes to the nets
4) simulate a Real Timing Simulation: the percentage of switching drivers will be
the real one.
Note: automatic interfaces between your logic simulator and
PRESTO can be easily implemented.
Contact HDT for more information about Real Timing Simulation
Simulating SSN
15-5

Running SSN analysis
• Set SSN button in the Simulation Setup window
• Set the SSN parameters: percentage of switching
drivers (100% in case of Real Timing Simulation)
and quiet state net class
• Run the simulation
Simulating SSN
15-6

SSN report
• The drivers to be set quiet are automatically chosen
by the system in a random way. The report file (.brep)
reports the configuration utilized for the simulation.
*** Simultaneous Switching Noise Report ***
Design name: xxxxxxx
--------------------------------------------------------------------------------
Pin name Net name Status Class
--------------------------------------------------------------------------------
Instance IC21 Component 74AC04 package DIP14 factory DEFAULT
2 /A(1) ACTIVE defaultcmos
12 /A(6) VICTIM defaultgnd
--------------------------------------------------------------------------------
...
...
Switching nets: net classes are
set by means of the Net Editor
window .
Quiet net: net class is a parameter of
the SSN setup and overrides the net
class assigned by means of the Net
Editor window during the SSN analysis.
Simulating SSN
15-7

SSN results
• Results can be obtained in ASCII or graphical
way, according to the setup of the simulation
setup menu
– if the setup is ASCII: the results are available in the .rep file as
masks violation reports
– if the setup is graphical: the results can be displayed with
SIGHTS as waveforms
t
Simulating SSN
15-8

Physical library
16-1
• Library Setup
• Special Nets
• Aliases setup
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19

Physical library
• Contains the physical model descriptions.
• Data base organized.
• Component creation and library management fully
supported by the PRESTO graphical interface.
• Support different component pinout description
associated to different package pinouts
Note: a component can be available in different packages. The pinout
of these can be different, so that more than one physical model can be
required for the same component. PRESTO searches the component in
the library data base using a key composed by the component and the
package name, so that the model can be correctly identified.
Physical library
16-2

Physical Model
Describes:
– the pinout of the component package
– the function of the pin (driver, receiver, power supply, etc)
– the name of the electrical model to utilize during the
simulation
1
2
3
4
5
6
7
8
9
FILE_TYPE=HDT_PLIB;
TIME=Thu Dec 10 10:45:33 1992
FAMILY=FACT;
PACKAGE SOIC14;
FACTORY=DEFAULT;
TYPE=IC;
NPINS=14;
BEGIN_PIN
FACT_DR24=2,4,6,8,10,12;
FACT_RC=1,3,5,9,11,13;
FACT_GND=7;
FACT_VCC=14;
END_PIN;
BEGIN_FUNCTION
DRIVER=2,4,6,8,10,12;
RECEIVER=1,3,5,9,11,13;
POWER_FACT=14;
GROUND_FACT=7;
END_FUNCTION;
END.
Physical library
16-3

Physical model types
• Resistors, capacitors, inductors, diodes
• Integrated circuits
• Programmable logic devices
• Connectors
• Special components
Physical library
16-4

Physical model definition
The model description is done by means of the Physical Model Editor
window. The resulting description can be saved directly in the
physical library or exported in a file having the Physical Model
Description format (ASCII file with .pmd extension)
Model parameters (library,
component name, pin number
and packages list)
Model description
Physical library
16-5

Physical Model Description format (PMD)
FILE_TYPE=HDT_PLIB;
TIME= xxxxxxxxxx
COMPONENT=component_name;
FAMILY=xxxxxxxx;
PACKAGE=xxx;
FACTORY=DEFAULT;
TYPE=xxxxx;
NPINS=nn;
BEGIN_PIN
model_name=pin_list;
END_PIN;
BEGIN_FUNCTION
function_name=pin_list;
END_FUNCTION;
BEGIN_POWER
power_name=pin_list;
END_POWER
BEGIN_CLASS
net_class_name=pin_list;
END_CLASS;
BEGIN_DR_LIST
driver_list;
END_DR_LIST;
BEGIN_VSET
voltage_value=pin_list;
END_VSET;
END.
Header
pin to electrical_model assignment
pin function (Driver, Receiver, Bidirectional, etc)
pin to power pin association: describes which
power/ground pin powers the other functions (driver,
receiver, etc) pins
default net class to pin assignment (not mandatory)
driver list (only if bidirectional, 3-state or open collector
functions are present in the model)
power supply voltage assignment (connectors only)
Physical library
16-6

R,L,C, Diodes
• These are two-pin models
• Only one electrical model can be associated to
the physical models
1 RECEIVER myresistor
2 RECEIVER myresistor
RES
DEFAULT
R 2
RES is the name of the
physical component
Default is the package
type for which
the model applies
“R” is the TYPE that applies
for resistors
The description requires the
pin name, the function
(always RECEIVER for these
components) and the name of
the electrical model (myresistor
in this case).
Physical library
16-7

Integrated circuits
• One electrical model has to be assigned to each
pin of the component functioning as DRIVER or
RECEIVER.
• Two electrical models have to be assigned to
each pin functioning as BIDIR, 3STATE, OPCOL
(one driver and one receiver models).
• An electrical model must be assigned to each pin
functioning as POWER. This model is utilized
during the analysis of the special nets (power and
ground nets) behavior.
Physical library
16-8

Example of IC description
1 RECEIVER ac_rc vcc gnd
2 RECEIVER ac_rct vcc gnd
3 DRIVER ac_dr8 vcc gnd
4 BIDIR ac_bd8 ac_rc vcc gnd
5 POWER vcc_mod vcc
6 POWER gnd_mod gnd
7 POWER gnd_mod gnd
8 ...
9 ...
MYIC
DIP14
IC 14
pin 1 has function RECEIVER, the electrical model to utilize is
“ac_rc” and the power pins of the electrical model must be
powered through the pins 5 and 6 (the package model will be
automatically connected).
pin 3 has function DRIVER and the electrical model to utilize is
“ac_dr8” (8mA driver in this case).
pin 4 is bidirectional, so two electrical models must be
specified: one will be used when pin 4 acts as DRIVER and the
other one when the pin acts as RECEIVER.
pins 5 and 6 are power and ground pins. They have a power
electrical model associated and a power name (vcc for pin 5
and gnd for pin 6 in this case)
1
2
3
4
5
6
7 8
9
1 0
1 1
1 2
1 3
1 4
v c c
g n d
(the package model is
not shown)
Physical library
16-9

Programmable Logic Devices (PLD)
• Their I/O description is not fixed but design dependent
(driver and receiver configuration is programmable).
• The same design can contain more than one PLD
device having identical part name but different pin
configuration (a different instance name of course)
• The description is similar to IC description but the
component name must contain the design and the
instance name with a special syntax.
part_name@instance_name@design_name
ex: IDTxxx@IC21@MYDES
Only the first 5 characters of the design name are necessary.
Physical library
16-10

Connectors (CON)
• Like PLD, the connector configuration is design
dependent
• While the previous models describe the drivers and
receivers inside the design, connector models allow the
description of drivers and receivers outside the design
and their interconnection to the circuitry inside the
design under test.
• If the external connections are known, connector
models allow you to accurately simulate also the
behavior of the interface interconnections.
• If the external connections are unknown, the
description of this model can be avoided using the
Default Models
Physical library
16-11

Connectors (2)
• Specific electrical models can be utilized to take into
account the actual external interconnections of
driver/receiver.
design under test
connector
physical
model
standard driver or
receiver
Special driver or receiver
with its actual
interconnection description
(RLC, TLM, behavioral, ...)
Physical library
16-12

Connectors (3)
• The component name of connectors is specified like
that of PLD devices (design-dependent components)
part_name@instance_name@design_name
e.g.: CONN5PIN@IP21@MYDES
Only the first 5 characters of the design name are required.
• One additional section of the description is utilized to
specify the power and ground supply of
driver/receivers models. In this way, it is also possible
to simulate ground voltage shift between the design
under test and the external circuitry and its effects on
signal integrity.
Physical library
16-13

Example of connector model
1 RECEIVER ac_rc 5 0
2 RECEIVER ac_rct 5 0
3 DRIVER ac_dr8 5 0.2
4 BIDIR ac_bd8 ac_rc 5.2 0
5 GENPOWER vee -4.5
6 GENPOWER gnd 0.0
7 ...
8 ...
9 ...
CON15@J1@TUTOR
CONN15PIN
CON 15
pin 1 is connected to a RECEIVER, the electrical model to
utilize is “ac_rc” and its power pins are connected to a 5/0V
power supply.
pin 3 is connected to a DRIVER and the electrical model to
utilize is “ac_dr8” (8mA driver in this case). The power pins
are connected to a 5/0.2 power supply
pin 4 is bidirectional, so two electrical models have to be
specified: one will be used when pin 4 acts as DRIVER and the
other one when the pin acts as a RECEIVER.
pins 5 and 6 are power and ground supply pins (GENPOWER
function). They have a power supply electrical model
associated and a supply voltage.
1
2
3
4
5
1 5
- 4 . 5 V
p o w e r n e t
d e s i g n
u n d e r
t e s t
e x t e r n a l
w o r l d
c o n n e c t o r
g r o u n d n e t0 V
6
5 V
0 V
5 V
5 V
5 . 2 V
0 V
0 V
0 . 2 V
Vset+ Vset-
Physical library
16-14

Special components
• These models describe the component as a black box,
and their internal structure is described by a SPRINT
netlist without explicit driver/receiver declaration. The
number of pins of the physical description must match
that of the related electrical model.
• SC modeling allows wide flexibility in modeling of the
internal functionality of the device. For example, it is
possible to build up models taking into account logic
and timing behavior of the core of the device (see
Electrical library section).
Physical library
16-15

Library management
• To insert a model in library:
– Create a model description.
– Choose Save in Library specifying:
» the target library
» the component name
» the package name
– If the library doesn’t already exist, a new one will be created.
• To extract a model from library:
– Choose Load Component Data specifying:
» the target library
» the component name
» the package name
– The model will be then displayed in the Model Editor window.
Physical library
16-16

Importing and exporting models
• To import a model from an ASCII file (PMD syntax):
– Select the Import command and specify the file to load.
– The model description will be loaded in the Component Editor
window.
• To write a model on an ASCII file (PMD syntax):
– Select the Export command and specify the output file name.
– The model description will be saved on the specified file.
16-17
Physical library

Electrical library
17-1
• Library Setup
• Special Nets
• Aliases setup
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19

Electrical library
• Contains the electrical model descriptions
(driver, receiver, passive components, etc).
• It is organized as a data base.
• Library management is fully supported by the
PRESTO graphical interface.
• Model architecture is fully user-definable
• Models are MODENV compatible
Electrical library
17-2

Modeling capabilities
• The models are described as .SUBCKT circuits in SPRINT syntax.
• The model architecture is user-definable.
• A set of default architectures is available for typical situations.
• All SPRINT primitives can be utilized within the model and in
particular:
– resistors, inductors, capacitors;
– non linear resistors
– time/voltage/current controlled resistors (switches)
– independent or voltage/current dependent sources
– dynamic or static transfer functions
– transmission lines
– time domain scattering parameters (including measure-based data).
• PRESTO allows the definition of hierarchical modeling (max. two
nesting levels).
Electrical library
17-3

Model types
• Driver/Receiver
– 4-pin models
– Suitable for ICs/PLDs/CONNECTORS I/O descriptions
– Selectable package
• R,L,C,Diodes, nonlinear resistors, voltage generators
– 2-pin models
– Suitable to model 2-pin passive components, IC power pins (to simulate the
behavior of supply nets, voltage power supply, etc)
• Special Components (SC)
– n-pin (n >= 1) models.
– utilized to model the behavior of a whole device, for example a resistive
array or an operational amplifier.
– allows the creation of complete electrical/logic/timing descriptions of
simple components.
Electrical library
17-4

Receiver Model
sources,
passive elem.,
measures,
power node
ground node
input node at "analog"
"logic" levels
"0" and "1"
0
1
output node atelectrical levels"V1" "V2"
V2
V1
etc
Input pin is automatically
connected to its external net
and acts as an electrical
load
Output pin provides a
digital signal (0 1)
obtained by an internal
threshold
Power and ground pins are
automatically connected to
the power and ground nets
supplying the device.component
power rail
ground rail
Electrical library
17-5
package

Example of simple CMOS receiver model
in
out
vcc
gnd
Cin
STF
Pvcc
Pgnd
1
2
10
20
E1
.SUBCKT name 1 2 10 20
CIN 1 0 value
PVCC 1 10 vcc_static_char C=1P
PGND 1 20 gnd_static_char C=1P
E1 2 0 1 20 THR( 2.5 0 1 )
.ENDS name
name is the name identifying the electrical model in the Sprint netlist,
value is the value of the input capacitance,
vcc_static_char is the static characteristic of the vcc clamping diode and
gnd_static_char is the static characteristic of the gnd clamping diode.
Usually, the static characteristic of the diode is expressed as a Piece Wise Linear fitting of its
actual V,I characteristic.
Electrical library
17-6

Driver model
sources,
passive elem.,
measures,
power node
ground node
input node at
"logic" levels
"0" and "1"
0
1
output node at "analog"
electrical levels"V1" "V2"
V2
V1
etc.
component
power rail
ground rail
Output pin is
connected to its net
and acts as a
generator
Power and ground pins are
automatically connected to
the power and ground nets
supplying the device.
Input pin is used by
Presto to connect the
driver to a digital
stimulus (0-1 levels) that
defines the switching
sequence
Electrical library
17-7
package

Example of CMOS driver model
out
vcc
gnd
Cout
2
10
20
Pvcc
Vcomp
E1
RSWvcc
+
+
Pgnd
RSWgnd
+
E0
Td
STF
STF DTF
DTF
1
in
SUBCKT name 1 2 10 20
COUT 2 0 value
RSWVCC 7 2 1 0 PWL(0V 1E6 1V 0 2V 0) C=2P
PVCC 7 8 1_static_char C=2P
E1 8 9 1 0 dtf stf 0.1NS
VCOMP 10 9 DC(5)
RSWGND 17 2 1 0 PWL(-1V 0 0V 0 1V 1E6) C=2P
PGND 17 18 0_static_char C=2P
E0 18 19 1 0 dtf stf 0.1NS
TD 19 20 C=6P
.ENDS name
name is the name of the electrical model within the Sprint netlist,
value is the value of the output capacitance,
1_static_char is the static characteristic of the output at "1" logic level,
0_static_char is the static characteristic of the output at "0" logic level,
stf is the static transfer function of the output and
dtf is the dynamic transfer function of the output.
Electrical library
17-8

Special components
component
power rail
ground rail
core
Any Sprint
netlist using
any Sprint
primitive
1
3
5
7
n -1
2
4
6
8
n
• PRESTO doesn’t provide automatic driver/receiver management for SC
• The internal description has to be complete and the output signals (to the external
nets) depend only by the input signals (coming from the external nets) or by signal
generated internally by means of user-defined voltage/current sources
• Allows the modeling of crosstalk between pins belonging the same package
Electrical library
17-9
package

Example of special component model
AC02 (four NOR):
1234567
gnd
vcc
standard
receiver model
8 9 10 11 12 13 14
R
1V
0V
Delay
Delay
Delay
2
3
1
Single NOR model
Four NOR models
A B OUT
0 0 1
1 0 0
0 1 0
1 1 0 standard driver model
pin crosstalk
model
Electrical library
17-10
. ..
timing/logic core

Importing and exporting models
• To import a model from an ASCII file (SPRINT syntax):
– Select a target library.
– Select the Import command and specify the file to load.
– The model description will be loaded in the target library.
• To write a model on an ASCII file (SPRINT syntax):
– Select a source library
– Select a model from the list displayed in the window
– Select the Export command and specify the output file name.
– The model description will be saved on the file.
Electrical library
17-11

• Library Setup
• Special Nets
• Aliases setup
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
18-1
Layout optimisation

Performing a “What-If?” analysis
• Check the effects of small modifications of the
design: “What happens if I try to … ?”
• Action at component level:
– deleting or changing the values of existing components
– inserting new components (e.g. decoupling capacitors,
matching resistors, noise sources)
• Action at layout level:
– deleting existing segments
– adding “physical” segments (with electrical properties defined
by their geometry)
– adding “electrical” segments (with electrical properties set up
by the user)
Layout optimisation
18-2

Friendly Graphic User Interface
Layout optimisation
18-3
Click with the center
button of the mouse on a
layout object (net, pin,
via) to identify it
Select What-If analysis to open the
optimisation window: it’s necessary to
choose if dealing with Components or
with Segments

Component optimisation
Layout optimisation
18-4
Currently deleted/ insereted/ modified
components. They are identified by:
• Component name (it’s the name of the
physical component as found in the library)
• Package name and Factory name
• Instance name
• Value (for passive component only)
• Type
Modification token “Enable/Disable”: this
allows to perform multiple simulation with or
without some modifications in order to point
out the best solution
Component
properties and pin
connection
window

Segment Optimisation
Electrical Segment
insertion window
Currently deleted/ insereted/
modified segments. Their related
net is displayed
Physical Segment
insertion window
18-5
Layout optimisation

• Library Setup
• Special Nets
• Aliases setup
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
19-1
EMI analysis

EmiR analysis flow
EMI analysis
A Signal Integrity
simulation with suitable
stimuli is performed
A Fast Fourier Transform
of the currents flowing
through the traces allows
the simulator to work
in the frequency domain
An analytical method based
on the Green dyadic is used
to evaluate the field
radiated by the traces
19-2

Time domain parameters setup
The simulation time window is completely
defined by the frequency parameters of EmiR:
• Tstart is 100ns, because the analysis in the time domain
must be “transient-free”
• Minimum working frequency: this affects the Tstop
parameter, because the FFT must be performed on a
complete period of the signal
• Maximum working frequency: this affects the
resolution parameter, because the FFT algorithm must
have enough sampled data to provide high frequency
results
• Simulation Time Step: the user can modify this
parameter, but a check is performed and an error
message is displayed if it’s too large compared to the
selected frequency domain
19-3
EMI analysis

EMI simulation characteristic
• The Cross Talk analysis is not compatible with
the EMI one
• Defined stimuli and delay are neglected (all the
nets are driven with a 50% duty cycle waveform
selected according to the minimum EMI
frequency), then:
– the analysis is made at only one digital frequency
– all the nets have signals “in phase”
– the even harmonics of the spectrum are very lower then the
odd ones (this depends on the 50% duty cycle)
19-4
EMI analysis

EmiR setup
Anechoic
chamber
analysis
Run EmiR
analysis
Semi-anechoic
chamber analysis
Near Field
analysis
Far Field
analysis
H-Field
spectrum
EMI Maps
Radiation
Diagram
E-Field
Spectrum
Far Field from
the board
Far Field from the
board with an
attached cable
EMI
ProfilesE-Field
Spectrum
19-5
EMI analysis

Anechoic chamber analysis
Select low frequency
algorithm
Provide all field
components:
(Ex, Ey, Ez)
Select results in Root Mean
Square dBuV/m
Select frequency
for radiation
diagram
19-6
EMI analysis

Semi-anechoic chamber analysis
Use a fixed height for the
antenna or perform a scan,
taking as results the
maximum field calculated at
each step
Define cable parameters.
NOTE: it is supposed to be
solded at the ground plane
of the board
19-7
EMI analysis

Presto training course_1999

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Presto training course_1999