Study of Finite Word Length Effects in Some Special Classes of Digital Filters

摘要

One of the main problems in digital filter implementation is that all practical devices are of finite precision. Therefore, the finite word length effect of digital filters is an area of high interest. There are various types of digital filter structures. Due to the effect of finite word length registers, each digital filter structure gives a slightly different output response for the same transfer function. Therefore, it is important to find the best filter structure which has the lowest affect on the output response for the same transfer function. In this paper, six IIR (Infinite Impulse Response) digital filters and six FIR (Finite Impulse Response) digital filters are investigated, theoretically, for the low sensitivity due to a finite work length register. In addition, the six FIR digital filters are simulated by computer to obtain practical results. Finally, it will be shown that NS (Nested Structure) digital filter produce the 'best' response if minimum sensitivity is the figure of merit. (Author)