In embodiments of the present disclosure, weighting on a direct current component coefficient dci′ of an I-channel signal and a direct current component coefficient dcq′ of a Q-channel signal is performed based on spatial leakage factors k1 and k2 of a microwave chip and a current attenuation amount of a tunable attenuator, to determine a corrected direct current component coefficient dci of the I-channel signal and a corrected direct current component coefficient dcq of the Q-channel signal, and a direct current component superimposed to the I-channel signal of the microwave chip and a direct current component superimposed to the Q-channel signal of the microwave chip are respectively determined based on the corrected direct current component coefficient dci of the I-channel signal and the corrected direct current component coefficient dcq of the Q-channel signal.