1. A source driver, comprising: N primary latching circuits, for respectively receiving N pixel data; a multiplexing device, coupled to the N primary latching circuits, for controlling signal transmitting routes of the N primary latching circuits; N digital-to-analog converting circuits, respectively having positive or negative signal outputs, each digital-to-analog converting circuit having a signal output polarity different from a signal output polarity of an adjacent digital-to-analog converting circuit, the N digital-to-analog converting circuits respectively generating N driving voltage signals according to the N pixel data; a switching device, coupled to the N digital-to-analog converting circuits, for controlling signal transmitting routes of the N digital-to-analog converting circuits; and N output circuits, for receiving the N driving voltage signals, and outputting N source driving signals to N pixels, successively; wherein the multiplexing device and the switching device alternatively switch polarities of a plurality of specific source driving signals respectively output by a plurality of adjacent output circuits within the N output circuits according to a polarity switching signal, respectively, where: the polarities of the specific source driving signals are positive, negative, negative and positive during a first period, respectively; and the polarities of the specific source driving signals are negative, positive, positive and negative during a second period, respectively.