An electronic device may be provided with wireless circuitry and a display. A display driver integrated circuit in the display may have a spectrum analyzer circuit. An antenna may monitor for wireless signals. The display driver integrated circuit may use the spectrum analyzer circuit to analyze the wireless signals and determine whether there is a potential for visible display artifacts. In the presence of conditions that can lead to display artifacts, the display driver integrated circuit may adjust a gate driver control signal. Adjustments to the gate driver control signal may be made using adjustable signal dividers. The adjustments to the gate driver control signal eliminate the visible display artifacts.