A self-contained hinge is disclosed for use in a flip-style device, such as a personal digital assistant. In one aspect, the OLED display includes a display substrate, an encapsulation substrate formed over the display substrate, and a window formed over the encapsulation substrate, wherein the window includes a surface facing the display substrate. The reference circuit includes a loop gain adjusting circuit having a switch for switching a gain. The plurality of circuits are arranged into a first and second set of circuits. The unit under test is insensitive to the interference signal and receives the result signal.