A transceiving circuit, which comprises: a transmitting circuit, configured to transmit a test signal; a receiving circuit, comprising a mixer configured to receive a plurality of predetermined DC bias voltage groups, wherein the receiving circuit generates a plurality of output signals according to the test signal while the mixer operates at the predetermined DC bias voltage groups; a frequency domain analyzing circuit, configured to transform the output signals to a plurality of frequency domain signals; and a DC bias voltage generating circuit, configured to generate a function according to the frequency domain signals and the predetermined bias voltage groups, and configured to generate a first DC bias voltage group to the mixer according to the function.