New low roundoff noise realizations of second-order digital filter sections

New structures for second-order filter sections are proposed that yield lower output roundoff noise than many well known structures and are free of zero-input limit cycle oscillations. These new low-roundoff structures are based on these suggested by Bomar (1989) and are obtained by putting the constraint that some of the state-space coefficients be sum-of-two power-of-two terms. Numerical results are included to illustrate the performance of the proposed structures for narrow-band filters and to compare them with other structures