Improvement of the noise behaviour of digital filters by transfer functioninvariant transformation of the flow graph matrix

In order to reduce the roundoff noise and to enhance the dynamic range of g eneral digital filters their flow graph matrix can be changed with transfor mation matrices. To do so, a suitable matrix representation of the filter i s introduced and the constraints for the transformation matrices for a tran sfer function invariant alteration are listed. After that, a procedure of n oise reduction on the basis of the introduced matrices is presented. As an example a block digital filter with 3 in- and outputs is used, for which th e roundoff noise could be improved from 9.8 dB to 4.0 dB with the given met hod.