A filtering device, applicable in a transceiver, includes: a capacitive circuit coupled to an amplifying circuit by a first capacitive configuration or by a second capacitive configuration; and a resistive circuit coupled to the amplifying circuit by a first resistive configuration or by a second resistive configuration; wherein when the capacitive circuit is the first capacitive configuration, the filtering device is used to perform a first filtering process upon a receiving signal of the filtering device, and when the capacitive circuit is the second capacitive configuration, the filtering device is used to perform a second filtering process upon a transmitting signal of the filtering device.