Answer
7—The
usual function of a guard ring on a PCB is to protect
sensitive circuit nodes from leakage currents and voltage
fields from nearby nodes by shunting them to ground or
some other reference voltage.
For
example, you might see a guard ring surrounding the input
pins of a high-input impedance op-amp used in a pH meter
and the connections to the probe. This helps prevent leakage
currents caused by surface contamination of the PCB from
affecting the readings.
Contributor: David Tweed
Published
February 2004
