A digital channelizer unit is proposed for a satellite digital payload capable of processing multiple digital input signals. The input signals are downsampled and converted to complex baseband signals for processing with the digital channelizer unit. Each complex baseband signal is then channelized into multiple channels. A routing module rearranges the channels, which are then reconstructed as new complex baseband signals. The new complex baseband signals are upsampled to a higher data rate and converted to digital passband signals.