A data transmission circuit comprises a plurality of data preparation circuits and a combiner. Each data preparation circuit receives a respective data stream and generates a respective sub-channel signal. Each respective data stream has a respective symbol rate and a respective Nyquist bandwidth. The combiner combines the respective sub-channel signals to generate a data transmission signal having an associated bandwidth. The bandwidth associated with the data transmission signal is greater than or equal to the sum of the Nyquist bandwidths for the respective data streams. Each data preparation circuit comprises a programmable linear equalizer that equalizes the respective sub-channel signal across the bandwidth of the data transmission signal.
