ETS-Lindgren 7405 E & H Near Field Probe Set - Manual (Page 43)

www.ets-lindgren.com Common Diagnostic Techniques 43
 Increasing decoupling of power to ground.
 Reduce lead or trace inductance by reducing their length or making
them wider.
 Inserting ground and power grids or planes.
 Shielding, using a ground separate from signal ground.
 Relocating I/O cables to a lower impedance area on the ground
structure.
 Placing common mode filters on the output lines using dissipating
elements.
Pre-Screening Alternate Solutions
Pre-screening allows you to sort through ideas, formulate test plans, and take
several viable solutions to the range. Pre-screening also provides empirical
evidence that a noise reduction technique has been correctly applied, and
indicates when you have properly analyzed the problem to the point of designing
an effective solution.
Testing alternate solutions can save time when troubleshooting an
electromagnetic problem. For example, for a common mode problem that
involves radiation from the end of a unit with the I/O connections, possible
solutions could include the following:
 Improve the decoupling on the board.
 Improve the power and ground grading or put in a ground plane.
 Decouple the end with the I/O connections to chassis ground.
 Place a common model choke on the output I/O.
The most economical solution may be a hybrid of these options applied in
conjunction. Each option could be implemented a number of ways, and the
physical mechanization of an approach will directly impact overall effectiveness.