New controllable noise suppression methods for near-magnetic field radiations on PCB using small active component circuits

A new method for suppressing near-magnetic field generated around a printed circuit board (PCB) is proposed. To implement this kind of noise suppression device, active components such as a varactor diode are introduced, thus realizing a small noise suppression circuit printed on the PCB with controllable resonant functions. Because the configuration of the small resonant circuit is designed to resonate with external unwanted magnetic fields, their propagation can be prevented on the PCB. Moreover, because of the introduction of active circuit components, the frequency of the field that should be suppressed can be controlled externally by changing the bias voltage. In this paper, the structure and validity of the noise suppression circuit printed on the PCB are clarified.