A frequency converter comprising a frequency transposition block for samples (11Q_1, 11Q_2), a filtering block (12Q_1, 12Q_2), the filtered samples y(n) verifying y(n)=c(0)·x(n)+c(1)·x(n−1)+c(2)·x(n−2)+ . . . +c(p−1)·x(n−p+1)+c(p)·x(n−p)+c(p−1)·x(n−p−1)+ . . . + . . . +c(1)·x(n−2·p+1)+c(0)·x(n−2·p), wherein x( ) are the transposed samples and c(0), . . . c(p) are the real coefficients of the filter; and being adapted for, during a cycle for determining the value of the filtered sample y(n): calculating the first terms c(0)·x(n), c(1)·x(n−1), c(2)·x(n−2), . . . , c(p)·x(n−p) by multiplying the respective coefficients and transposed samples, and storing in memory said first calculated terms; reading the second terms c(p−1)·x(n−p−1), . . . , c(1)·x(n−2·p+1), c(0)·x(n−2·p), calculated and stored in memory during previous cycles for determining the value of filtered samples y(n−m); and determining y(n) by summation of the first and second terms.