One of the most-used filter forms is the biquad. A biquad is a second order (two poles and two zeros) IIR filter. It is high enough order to be useful on its own, and—because of coefficient sensitivities in higher order … Continue reading →

Here’s a Java applet that illustrates pole-zero placement. It lets you design a filter with two poles and two zeros, while showing the resulting frequency response and filter coefficients. It’s also handy for learning more about how poles and zeros … Continue reading →