An optical plate includes a first surface, a second surface opposite to the first surface, a plurality of substantially parallel arc-shaped depressions defined in the first surface and a plurality of elongated arc-shaped protrusions and elongated V-shaped protrusions protruding out from the second surface. Example embodiments may include preventing snap-back current in a circuit including a first NMOS transistor having an associated parasitic bipolar transistor. The magnetic field generating device includes a plurality of magnetic regions having alternating magnetic directions such that magnetic flux generated by the magnetic field generating device is enhanced on a first side of the magnetic field generating device and inhibited on a second side of the magnetic field generating device.