A power efficient and reduced electromagnetic interference (EMI) emissions transmitter
for unshielded twisted pair (UTP) data communication applications. Transmit data
is processed by a digital filter. The digital filter output data is converted to
a current-mode analog waveform by a digital-to-analog converter (DAC). The digital
filter is integrated with the DAC binary decoder in a memory device such as a ROM
with time multiplexed output. DAC line driver cells are adaptively configurable
to operate in either a class-A or class-B mode depending on the desired operational
modality. A discrete-time analog filter is integrated with the DAC line driver
to provide additional EMI emissions suppression. An adaptive electronic transmission
signal cancellation circuit separates transmit data from receive data in a bidirectional
communication system operating in full duplex mode. For a multi-transmitter system,
timing circuitry staggers the time base of each transmitter to reduce the aggregate
EMI emissions of the multi-transmitter system.