A wireless receiver includes a radio frequency (RF) receiving unit and a baseband receiving unit. A first path of the RF receiving includes a first filter, and is arranged for receiving an input RF signal and generating a first baseband input signal; a second path is arranged for receiving the input RF signal and generating a second baseband input signal. The baseband receiving unit is arranged for receiving the first baseband input signal and the second baseband input signal to generate a baseband decoded signal. One of the first path and the second path is an in-phase path, and the other is a quadrature-phase path. When the RF receiving unit operates in a first mode, the RF receiving unit only uses the first path to receive the input RF signal.