Alessandro ARNULFO R&D Application Engineer

PRESTO_POWER

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Now PRESTO is able to take into account noise

propagation in any shape copper area.

PRESTO_POWER is an high performance

software tool to simulate high speed PCB taking

into account EMC phenomena as bouncing on

power plane.

PRESTO POWER

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CAD

Extraction

Sim. Set Up

Creation of

SPRINT netlist

SPRINT

Display

Results

SUBCIRCUITS of each

copper area are linked to

the other circuit elements.

Extraction of

copper areas and

planes shape

Possibility to model

planes or not

PRESTO ver. 3.2 New features implemented

in PRESTO_POWER

PRESTO_POWER flow

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• Power plane modelling

- ground bouncing (noise propagation)

- filtering (bypass C placing optimisation )

• Gridding algorithm

•Conclusion

NEXT STEPS

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Power planes modelling is necessary to

simulate effects such as:

• noise propagation and ground bounce

influence on signals

• simulation of power plane filtering effect

• optimisation of bypass capacitors

placement on PCB

POWER PLANES MODELLING

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Power planes modelling is

necessary to simulate the

noise propagation and

ground bounce effect on

signals

NOISE PROPAGATION

& GROUND BOUNCE

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Gate

Very large

power

supply

inductance

Power supply

input drops to zero

The gate may no

longer work or

break into

oscillation

POWER PLANE FILTERING

POWER

SOURCE

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- Bypass capacitor insertion

- Filtering through interplane capacitance between

power planes

SOLUTIONS:

Gate POWER

SOURCE

POWER PLANE FILTERING

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WHAT IF ANALISY FOR

BYPASS CAPACITOR

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Power planes modelling is

necessary to:

• simulate the power planes

filtering effect

• optimise bypass capacitors

placement on PCB

POWER PLANE FILTERING

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The model, used to describe the area, is a grid of

losses transmission lines. This requires a mesh

with square cells. This choice guarantees the

same propagation delay for all transmission line.

GRID OF LOSSY

TRASMISSION LINE

UNIFORM Td

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Flexibility:

each metal area can have a

different, optimised grid step

Parameters related to the grid step:

• Tstep : minimum time resolution

• max N_row : user-defined grid row limits

• max N_col : user-defined grid column limits

MESH GENERATOR

5V

3.3V

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Propagation speed (cross-section of PCB)

Tstep (set up in simulation)

dstep (spatial resolution)

Single cell must

have dimensions

multiple of dstep

micro-grid

dstep

GRID CHOICE ANALISY

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Result after the

meshing algorithm.

The rectangular

boundary is gridded

with a regular mesh.

0% 88% 100% 0%

AN EXAMPLE OF GRIDDED AREA

ZOOM

IN

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POWER PLANE MODEL (ZOOM)

grid on which is built

TL network

grid_step dstep

micro-grid linked to tstep

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COPPER AREA GRIDDED

Completely filled

Partially filled

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User can choose to model:

• POWER NET: PLANES SPLITTED PLANES

• SIGNAL NET

Areas connections topology:

• SEGMENT - AREA

• VIA - AREA

• PIN - AREA

POWER PLANES MODELLING

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The user can choose to model or

not signal and/or power areas

Gridding settings

AREAS SETTING

USER INTERFACE

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POWER PLANES MODELLING

FOR MERITA PROJECT

When several gates switch

simultaneously, a large amount of noise

is injected into power and ground pins

The power planes model is used to

evaluate noise voltage on power and

ground planes.

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CONCLUSION

MOST IMPORTANT ACHIEVEMENT

Copper areas modelling integration in

PRESTO

FUTURE STEP

Taking into account coupling effects

between copper area