DS42BR400,pdf datasheet (Quad

The DS42BR400 is a quad 250 Mbps – 4.25 Gbps CML
transceiver, or 8-channel buffer, for use in backplane and cable
applications. With operation down to 250 Mbps, the
DS42BR400 can be used in applications requiring both low
and high frequency data rates. Each input stage has a fixed
equalizer to reduce ISI distortion from board traces. The
equalizers are grouped in fours and are enabled through two
control pins. These control pins provide customers flexibility
where ISI distortion may vary from one direction to another.
All output drivers have four selectable steps of de-emphasis
to compensate against transmission loss across long FR4
backplanes. The de-emphasis blocks are also grouped in
fours. In addition, the DS42BR400 also has loopback control
capability on four channels. All CML drivers have 50Ω termination
to VCC. All receivers are internally terminated with
differential 100Ω.