A transmitter includes a first wireless communication module, a second wireless communication module, a multiplexer, a digital-to-analog converter and a filter. The multiplexer selectively outputs a first digital signal derived from a digital output of the first wireless communication module or a second digital signal derived from a digital output of the second wireless communication module as a selected output. The digital-to-analog converter converts the selected output into an analog signal. The filter processes the analog signal and includes an adjustable resistive element. When the multiplexer selects the first digital signal as the selected output, the adjustable resistive element is adjusted to have a first resistance value such that the filter has a first bandwidth. When the multiplexer selects the second digital signal as the selected output, the adjustable resistive element is adjusted to have a second resistance value such that the filter has a second bandwidth.