RGMII

　　簡(jiǎn)化的吉比特媒體獨(dú)立接口稱(chēng)為RGMII（Reduced Gigabit Media Independent Interface）。采用RGMII的目的是降低電路成本，使實(shí)現(xiàn)這種接口的器件的引腳數(shù)從22個(gè)減少到12個(gè)。
　　RGMII is a reduced pin count interface that can simplify design by reducing the interface pin count from the 25pins used in the GMII interface to 12. It can lower system cost compared to existing GMII or TBI interfaces by reducing the number of layers required to route high density networking solutions. Using RGMII, fewer pins are required for the MAC/switch ASIC, which can reduce the MAC/switch cost by enabling smaller die sizes than would be possible with GMII or TBI. However, the RGMII specification calls for a timing delay on both the receive signal and the transmit signal for each port that must be implemented in a board level trace. These trace lengths are typically arranged in a spiral on the board that takes approximately one square inch of board space per trace. Broadcom offers an alternative timing solution that eliminates the need for the timing delay traces. Assuming a one-inch space requirement per trace for both transmit and receive signals on 48 ports, elimination of the timing delay traces can save 96 square inches of layout space.

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