Signality Solutions

Signal Integrity and EMC

Analogue and high speed digital design, Signal Integrity (SI) and EMC and power supply are all different aspects of the same analogue world.

Electronic components and systems are getting faster. Bandwidths are increasing; Data rates are increasing; Edge speeds are increasing; Component densities are increasing; Time to market is reducing.

As bandwidths, data rates, edge speeds and component densities climb, signals can no longer be treated in isolation. Digital signals can no longer be treated as simple logic ones and zeroes. Schematic capture and PCB design cannot be separated. The combined effects of device parasitics, crosstalk and transmission line behaviour can no longer be ignored if a design is to be successful.

Failure to understand and properly manage these effects can result in:

• erratic circuit behaviour
• excessive radiated emissions (RFI)
• poor radiated and conducted immunity

At best that leads to costly redesigns.

At worst your product can fail to reach the market in a timely manner.

Signality Solutions can help you avoid these pitfalls by providing specialist expertise for key areas of your product design from concept through design, simulation, schematic capture, PCB design and test.

SI is an increasingly important aspect of electronic design. Even apparently low speed circuitry can be adversely affected by:

• Crosstalk from;
• adjacent traces;
• signals crossing plane breaks;
• switching power supplies;


• Reflections from;
• signal transitions between different PCB layers;
• incorrect trace or termination impedances;

Failure to correctly manage SI can mean that an apparently error free schematic and PCB layout will not work together, creating a debugging nightmare.

Whilst SI management can significantly improve EMC performance, steps taken to improve EMC in isolation can actually degrade SI.

By understanding that SI and EMC are just different aspects of analogue design and applying modelling and simulation techniques to study pre- and post- layout circuit behaviour, successful design for SI and EMC can be built in from the beginning of a project. Potential problems can be fixed before you commit to PCB, saving costly redesigns and respins.

However, design for SI and EMC is only one part of the process. The use of correct measurement techniques is crucial to SI. Poor measurement techniques can hide true signal behaviour, falsely indicate - or even be the cause of - bad SI in a circuit.

Signality Solutions can advise on measurement techniques and has developed specialist modelling techniques to ensure that simulation results can be realistically compared with measured results.

If you want to get your signal integrity right by design then please contact us.