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.


在一個數(shù)字濾波器發(fā)展的重要步驟是可實現(xiàn)的傳遞函數(shù)G（z）的接近給定的頻率響應規(guī)格。如果一個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）的過程稱為數(shù)字濾波器的設計。然后G（z）有所值，下一步就是實現(xiàn)在一個合適的過濾器結(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)字濾波器的設計問題。FIR數(shù)字濾波器的設計是在第10章處理。
首先，我們回顧與濾波器設計問題相關(guān)的一些問題。一種廣泛使用的方法來設計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)進行了討論下一步。典型的設計實例來說明這種方法。然后，我們考慮到另一種類型，它是由一個函數(shù)代替復雜的變量z達到了一個IIR濾波器的傳遞函數(shù)z的類型轉(zhuǎn)換四種常用的轉(zhuǎn)換進行