A network device is provided which includes a device input, at least one
port, a frequency doubler, a data I/O device, and a programmable delay
locked loop. The frequency doubler is coupled to the input and configured
to receive an input signal and output an output signal having double the
frequency of the input signal. The data I/O device is configured to
output data based upon a reference clock signal. The programmable delay
locked loop is coupled to the device input and configured to receive an
input signal and to automatically output an output signal being a
predetermined amount out of phase from the input signal. An external
clock signal received at the device input is input to the frequency
doubler. The output of the frequency doubler is input to the data I/O
device as a reference clock. Data (e.g., from internal device logic) is
output from the data I/O device to the at least one port. The external
clock signal is input to the programmable delay locked loop, which
outputs an output clock signal having a frequency equal to the frequency
of the external clock signal, in synchronization with the data being
output.