SATA clock details required

[marrirohit]

can any one say that why do we go for 37.5 MHz system clock frequency in case of SATA-I (1.5 Gbit/s data transfer rate) mode and at 75 MHz in case of SATA-II (3.0 Gbit/s data transfer rate) mode. apart from system(cpu) clock.....

can any one post a verified phy layer of SATA...