Integrated circuit, system, method and machine readable media embodiments
adjust a slew rate and/or a transmit pre-emphasis of an output signal at
selected phases during a bit time. A timing circuit provides a plurality
of delayed data signals in response to a clock signal. A plurality of
adjustable impedance circuits, including a plurality of select circuits,
output a plurality of selected delayed data signals to form the output
signal having an adjusted slew rate. Delay elements in the timing circuit
are also biased from a current of a lock loop circuit to further adjust
slew rate of the output signal. Transmit pre-emphasis of the output
signal is adjusted by selecting a polarity of a selected delayed data
signal in each of the plurality of adjustable impedance circuits. Each
adjustable impedance circuit also includes a predriver and driver for
adjusting impedance in response to a signal indicating an impedance
value. In an embodiment, an integrated circuit is able to operate in
multiple modes of operation depending upon the type of output signal,
frequency range of the output signal, physical packaging and/or system
configuration.