A method and a device of sampling an analog signal (U(t)) by obtaining first sequences of discrete sample values (S1I(t), (S1q(t)) of In-phase (I) and Quadrature-phase (Q) components (Ui(t), Uq(t)) of the analog signal (U(t)) and second sequences of discrete sample values (S2I(t), (S2q(t)) of the I and Q components (Ui(t), Uq(t)), by sampling of the I and Q components with sampling sequences (Ζ1(t), Ζ2(t)) having equal sampling rate (φs) and a mutual phase shift of 90° relative to their sampling rate period (T). The sample values of the I component of the first sequence (S1I(t)) and the sample values of the Q component of the second sequence (S2q(t)) are summed (9) to form a third sequence of sample values S3(t). The sample values of the Q component of the first sequence (S1q(t)) and the sample values of the I component of the second sequence (S2I(t)) are summed (10) to form a fourth sequence of sample values (S4(t)). The third and fourth sequences of sample values (S?3(t), (S4¿(t)), are further processed during an interval of a particular period (T) of the third and fourth sequences (S?3(t), (S4¿(t)) and starting after the sample values of the first and second sequences (S1I(t), (S2I(t), (S1q(t)), (S2q(t)) of said period (T) are available.