Department of Microelectronics,

Indian Institute of Information Technology, Allahabad

SUBMITTED BY:

Prashant singh(imi2011003)Rahul Patidar(imi2011011)

Introduction Classification Types Structures Digital Vs Analog filters Refrences

Electronic circuits which perform signal processing functions, remove unwanted frequency component, to enhance wanted ones, or both.

Digital filter-Performs mathematical operations on a sampled,discrete time signal to reduce or enhance certain aspects of that signal.

Filters generally do not add frequ- ency components to a signal. Boost or attenuate selected frequ- ency regions.

Digital Fil tering

Magnitude response consideration. Four basic types of ideal filters with magnitude responses as shown

below

π

1

ω0 ωc –ωc

HLP(e jω)

− π π ω

0 ωc –ωc

1

HHP (e jω)

− π

π− π ω

11–

–ωc1 ωc1 –ωc2 ωc2

HBP (e jω)

− π π ω

1

–ωc1 ωc1 –ωc2 ωc2

HBS(e jω)

Depending on the form of the filter equation (a) Linear filters versus nonlinear filters.

(b) Time-invariant filters versus time-varying filters.

(c) Adaptive filters versus non-adaptive filters. (d) Recursive versus non-recursive filters.

Depending on the structure of implementation(a) Direct-form, cascade-form, parallel-form and lattice structures.

A class of linear filters whose behavior does not change over time- Linearity implies that the filter meets the scaling and superposition properties.

Two types1.FIR filter

-Operate only on previous values of the input

2.IIR filter-Operates on previous values of input & output both

A recursive filter has feedback from output to input, and in general

its output is a function of the previous output samples and the present and past input samples

A non recursive filter has no feedback from output to input, and in general its output is a function of the present and past input samples

Direct Form

Direct Filter Structure

Cascade Form

Cascade Filter Structure

Parallel Form

Parallel Form Structure

DIGITALHigh AccuracyLinear Phase (FIR Filters)Flexible, Adaptive Filtering PossibleEasy to Simulate and DesignComputation Must be Completed inSampling Period - Limits Real Time OperationRequires High Performance ADC,DAC & DSP

ANALOGLess Accuracy–Component Tolerances

Non-Linear PhaseAdaptive Filters DifficultDifficult to Simulate and DesignAnalog Filters Required at High Frequencies and for Anti-Aliasing FiltersNo ADC, DAC, or DSP Required

Introduction to Speech Processing | Ricardo Gutierrez-Osuna | CSE@TAMU, chapter 10 of [Taylor, TTS synthesis, 2009]. An Introduction to Digital Filters,application note,january1999, Intersil and Design is a trademark of Intersil Corporation. |

Copyright©Intersil Corporation 2000 Digital Filters and Z Transforms,Copyright © Richard C. Bailey and David M. Harrison, 1998, 1999 http://en.wikipedia.org/wiki/Digital_filter