Electromagnetic Interference (EMI) plays a significant role on degraded image quality under specific operating conditions. During our product characterizations, we analyzed an event that shows bright vertical chain‐like spots on mobile Organic Light‐emitting Diode (OLED) display due to the transmit operation of Global System for Mobile (GSM) phone nearby the device under test (DUT). The cause of the event is laid out as follows. The transmitted Radio Frequency (RF) power travels through Flexible Printed Circuit (FPC) to Display Driver Integrated Circuit (DDIC). Then the transistors respond to RF power as unintended RF diodes, which generate unexpected Direct Current (DC) voltage, which pushes the panel‐driving buffer Operational Amplifier's (OPAMP) output drifted.