Physical Medium Attachment isomers circuitry for an integrated circuit device

An integrated circuit comprising a physical medium attachment or access ( "PMA") circuitry, which includes a transceiver channels for two different types of serial data signals 5. A transceiver adapted to transmit and receive channels of relatively low speed serial data signal. Another channel transceiver adapted to transmit and receive a relatively high-speed serial data signals. Alternatively, the high-speed channel 10 may be phase-locked loop ( "PLL") circuitry for providing a clock signal used by the other high and / or low-speed channels. Alternatively, the low-speed channel clock signal may be obtained from a separate low-speed PLL circuit.