differential mode noise

what causes differential mode noise..can u explain with reference any
power converter...buck,boost any?
how it is generated and how it propagates to source
thanks

 

[John Popelish]

krishmaniac@hotmail.com wrote:

what causes differential mode noise..can u explain with reference any
power converter...buck,boost any?
how it is generated and how it propagates to source
thanks

If you have a signal line referred to a common, and any voltage gets
added (put in series) between them, that is a differential noise. One
of the most common causes is the signal to common loop encloses
changing magnetic field, which induces voltage in the loop. It is
also possible for changing electric field that terminates on both
signal and common lines to cause currents that produce different
voltages due to different impedances in the path of each of the
currents, and this will cause differential noise.

In power converter circuits, the magnetic and electric fields can
originate in the converter, itself, and contaminate voltage reference
or voltage or current measurement signals. More often, differential
noise is caused just by the large current and rate of change of
current in traces and planes that cause these conductors (that are
often expected to be zero drop nodes) to have significant voltage
differences between different locations due to resistance and inductance.