Integrated circuits often include cascade Metal-Oxide-Semiconductor (MOS) devices. The cascade MOS devices may be used in power circuits. In some circuits, each of the MOS devices (referred to as large MOS devices hereinafter) is implemented by connecting a plurality of MOS devices (referred to as small MOS devices hereinafter) in parallel, which means that sources of all of the small MOS devices are interconnected, gates of all of the small MOS devices are interconnected, and drains of all of the small MOS devices are interconnected.
For example, when there are two large MOS devices cascaded, the source of the first large MOS device is connected to the drain of the second large device. The first large MOS device is implanted by connecting a first plurality of small MOS devices in parallel. The second large MOS device is implanted by connecting a second plurality of small MOS devices in parallel. The sources of the first plurality of small MOS devices are thus connected to the drains of the second plurality of small MOS devices, for example, through metal lines, vias, and/or contact plugs.