On the measurement of quantization noise in digital filters

Quantization noise in digital filters caused by magnitude truncationi exhibits a rather strong correlation with the main signal. Therefore, such noise signals are appropriately considered as sums of completely correlated and completely uncorrelated components. The first component can be interpreted as a slight change of the linear transmission characteristic of the filter whereas the second part reflects the genuinely nonlinear properties induced by quantization. Results of measurements are given; these show that the latter part accounts for a relatively small percentage of the total noise. The separation of noise components also applies to controlled rounding which is shown to be reducible to magnitude truncation.