Reduce Inductive Coupling From Diesel Ford Injection Control Module PCB Design
As with most other noise sources, as soon as we define the working principle, we can see ways of Reduce Inductive Coupling From Diesel Ford Injection Control Module PCB Design. In this case, reducing any or all of the terms in the equations in below Figure reduces the coupling. Reducing the frequency or amplitude of the current causing the interference may be impracticable, but it is frequently possible to reduce the mutual inductance between the interfering and interfered with circuits by reducing loop areas on one or both sides and, possibly, increasing the distance between them.
Basic Principles of Inductive Coupling
A layout solution is illustrated by below Figure. Here two circuits, shown as Z1 and Z2, are minimized for coupling by keeping each of the loop areas as small as is practical.
Proper Signal Routing and Layout Can Reduce Inductive Coupling
As also illustrated in below Figure, mutual inductance can be a problem in signals transmitted on cables. Mutual inductance is high in ribbon cables, especially when a single return is common to several signal circuits (top). Separate, dedicated signal and return lines for each signal circuit reduces the problem (middle). Using a cable with twisted pairs for each signal circuit as in the bottom picture is even better (but is more expensive and often unnecessary).
Mutual Inductance and Coupling Within Signal Cabling
Shielding of magnetic fields to reduce mutual inductance is sometimes possible, but is by no means as easy as shielding an electric field with a Faraday shield (following section). HF magnetic fields are blocked by conductive material provided the skin depth in the conductor at the frequency to be screened is much less than the thickness of the conductor, and the screen has no holes (Faraday shields can tolerate small holes, magnetic screens cannot).
LF and DC fields may be screened by a shield made of mu-metal sheet. Mu-metal is an alloy having very high permeability, but it is expensive, its magnetic properties are damaged by mechanical stress, and it will saturate if exposed to too high fields. Its use, therefore, should be avoided where possible from PCB Reverse Engineering.
