Analyzing finite-wordlength effects in block state space filters

Periodically time-varying distortions arising in block state space (BSS) filter structures due to coefficient quantization may contribute significantly to the total amount of distortions observed in the output signal. A theoretical concept for analyzing both aliasing/imaging and roundoff noise in BSS structures is discussed. The measurement method reported by R.L. Reng and H.W. Schuessler (1992) is applied to BSS filters implemented with unbiased rounding and two´s complement truncation. With a data path wordlength of 16 bits the measurement results are in excellent agreement with the theoretical results. The measurement method is also applicable if the assumption of inserting uncorrelated noise at the rounding points is not valid.<>