The document discusses different types of digital filters including Infinite Impulse Response (IIR) filters and multirate filters. IIR filters use feedback and have an infinite impulse response. They are potentially unstable but more efficient than FIR filters. IIR filters are usually designed to duplicate analog filter responses and implemented as cascaded second-order sections. Multirate filters involve changing the sample rate, such as decimation which decreases the sample rate, and interpolation which increases the sample rate. Adaptive filters can modify their transfer function based on an optimization algorithm to model non-stationary signals and are used for applications like echo cancellation.

3. Bandpass and Bandstop Filters Designed from Lowpass And Highpass Filters

5. Hardware Implementation Of Second-order IIR Filter (Biquad) Direct Form 1

6. IIR Biquad Filter Direct Form 2

7. IIR Biquad Filter Simplified Notations

11. Comparison Between FIR and IIR Filters

12. Decimation Of a Sampled Signal By a Factor of M

13. Decimation Combined With FIR Filtering

14. Interpolation by a Factor Of L

15. Effects of Interpolation on Frequency Spectrum

17. Sample Rate Converters

18. Adaptive Filter

19. Digital Transmission using Adaptive Equalization

20. Linear Predictive Coding (LPC) Model of Speech Production

21. LPC Speech Companding System

22. All Pole Lattice Filter

23. Estimation of Lattice Filter Coefficients in Transmitting DSP