Approaches for preparing a design of a digital multirate filter. Air jet interactions are generated at cooling passage intersections when air is passed through the cooling passages. The method sets a transmitting antenna or receiving antenna of the transmitting end or receiving end to a smart antenna solely, or sets them to smart antennas simultaneously. As a result, by using a separate mask and by selecting a period of time for etching to active gates, gate contact openings can be formed during manufacture of ICs, semiconductors, MOS memory cells, SRAM, flash memory, and various other memory cells. In one embodiment, multiple versions of the reference signal are generated having different phases relative to one another, and these multiple versions are combined to form an output signal having a frequency that is a multiple of the frequency of the reference signal.