Infinite impulse response or IIR filters are designed using well-established designs for continuous-time filters. In this series of eight lessons you will learn the characteristics of the four widely used types of IIR filters and the principles of converting a continuous-time prototype filter to a discrete-time filter that satisfies your design specifications. In practice the steps of the design process are normally performed using a software package such as MATLAB. You will learn the rationale behind and limitations of IIR filter design methodology. Examples of both good and poor quality filter designs are provided so you can recognize when your design is effective and when it is problematic.