Based on 4-level pulse amplitude modulation (PAM) technology, 28 nm Models BCM82040 and BCM82004 enable transmission rates of 40/50 Gbps serially over multiple physical media, including direct attach cables and optical fiber. PAM-4 enables transmission of 40 Gbps at baud rate of 20 Gbaud. Housed in 7 x 7 mm package, both devices can transmit and receive data over 2 pairs of media versus 8 pairs of media using existing 4 x 10G quad small form-factor pluggable cables.