An important step in the development of a digital filter is the determination of a realizable transfer function G(z) approximating the given frequency response specifications. If an IIR filter is desired,it is also necessary to ensure that G(z) is stable. The process of deriving the transfer function G(z) is called digital filter design. After G(z) has been obtained, the next step is to realize it in the form of a suitable filter structure. In chapter 8,we outlined a variety of basic structures for the realization of FIR and IIR transfer functions. In this chapter,we consider the IIR digital filter design problem. The design of FIR digital filters is treated in chapter 10.
First we review some of the issues associated with the filter design problem.


在一個(gè)數(shù)字濾波器發(fā)展的重要步驟是可實(shí)現(xiàn)的傳遞函數(shù)G（z）的接近給定的頻率響應(yīng)規(guī)格。如果一個(gè)IIR濾波器是理想，它也有必要確保了G（z）是穩(wěn)定的。該推算傳遞函數(shù)G（z）的過(guò)程稱為數(shù)字濾波器的設(shè)計(jì)。然后G（z）有所值，下一步就是實(shí)現(xiàn)在一個(gè)合適的過(guò)濾器結(jié)構(gòu)形式。在第8章，我們概述了為轉(zhuǎn)移的FIR和IIR的各種功能的實(shí)現(xiàn)基本結(jié)構(gòu)。在這一章中，我們考慮的IIR數(shù)字濾波器的設(shè)計(jì)問(wèn)題。FIR數(shù)字濾波器的設(shè)計(jì)是在第10章處理。
首先，我們回顧與濾波器設(shè)計(jì)問(wèn)題相關(guān)的一些問(wèn)題。一種廣泛使用的方法來(lái)設(shè)計(jì)IIR濾波器的基礎(chǔ)上，傳遞函數(shù)原型模擬到數(shù)字的轉(zhuǎn)換傳遞函數(shù)進(jìn)行了討論下一步。典型的設(shè)計(jì)實(shí)例來(lái)說(shuō)明這種方法。然后，我們考慮到另一種類型，它是由一個(gè)函數(shù)代替復(fù)雜的變量z達(dá)到了一個(gè)IIR濾波器的傳遞函數(shù)z的類型轉(zhuǎn)換四種常用的轉(zhuǎn)換進(jìn)行