What is a Filter Circuit?: A network designed to attenuate certain frequencies but pass others without attenuation is called a filter. A filter circuit thus possesses at least one pass band, which is a band of frequencies in which the output … (Read More)

What are Passive Filters?: Passive filters are mainly networks using inductors, capacitors and resistors. The classical theory employed was based on the image parameter theory which in turn was based on the filter’s characteristics and performance. Its component values were calculated … (Read More)

Types of Filters in Electronics: Types of filters in electronics may be of any physical form—electrical, mechanical, pneumatic, hy­draulic, acoustical, etc. The most commonly used filters are of the electrical type. Types of filters in electronics may be classified as follows. Low … (Read More)

Classification of Active Filters: An electric filter is often a frequency selective circuit that passes a specified band of frequencies and blocks or attenuates signals of frequencies outside this band. Classification of Active Filters are as follows. Analog or digital filters Passive or … (Read More)

Low Pass Filter Circuits: The Low Pass Filter Circuits of Fig. 15.7 is commonly used for low pass active filters. The filtering is done by the use of an RC network. The opamp is used as a unity gain amplifier. The … (Read More)

Second Order Low Pass Butterworth Filter Derivation: A stop band response having a 40 db/decade roll off is obtained with a Second Order Low Pass Butterworth Filter Derivation A second order filter can be obtained by coupling two active filters having a … (Read More)

First Order High Pass Butterworth Filter Derivation: First Order High Pass Butterworth Filter Derivation – High pass filters are often formed by interchanging frequency determining resistors and capacitors in a low pass filter. A first order high pass filter is formed from … (Read More)

Second Order High Pass Butterworth Filter Derivation: As in the case of a first order filter, a second order high pass filter can be formed from a second order low pass filter by simply interchanging the fre­quency determining resistance and capacitor. … (Read More)

Higher Order Filter Design: From the preceding discussion on filters we can conclude that in the stop band the gain of the filter changes at the rate of 20 db/decade for first order filters and 40 … (Read More)

Band Pass Filter Circuit Diagram: A Band Pass Filter Circuit Diagram designed to pass signals only in a certain band of frequencies while rejecting all signals outside this band. There are basically two types of Band Pass Filter Circuit Diagram, Wide band … (Read More)

Band Reject Filter Circuit: In this Band Reject Filter Circuit, frequencies are attenuated in the stop band and passed outside it, as shown in Fig. 15.20(b). As with band pass filters, band reject filters can also be classified as (i) wide … (Read More)

All Pass Filter Design: The All Pass Filter Design is one that passes all frequency components of the input signal without attenuation. Any ordinary wire can be used to perform this char­acteristic but the most important factor in an all pass … (Read More)

Universal Active Filter using Op Amp: With the advance of integrated circuit technology, integrated circuits with improved capabilities are appearing in ever increasing numbers. Innovative design methods and fabrication procedures have not only helped to produce a large variety of new … (Read More)

Types of Active Filters: There are basically four useful Types of Active Filters. Namely Butterworth Filter Chebyschev Filter Bessel Filter Elliptic Filter Butterworth Filter: The Butterworth filter has an essentially flat amplitude versus frequency response up to the cutoff frequency. The sharpness of the cutoff can be … (Read More)

Introduction to Digital Filtering: It has been seen that control of the band width of a circuit or signal is of paramount importance in optimizing the measurement of a signal. Formerly band width control was implemented using frequency, selective active or … (Read More)

Properties of Linear Digital Filters: The properties of linear digital filters defined as transformations of discrete functions are described in the following. Discrete Functions Equation are defined only for discrete values of their variables, that is, they are sequences of numbers. … (Read More)

Sampling Theorem Formula 1-D: One of the most important applications of digital filtering is the processing of sequences of samples derived from continuous or analog signals. This is made possible due to the results and implications of the Sampling Theorem Formula. This … (Read More)

What is Digital System?: Fundamental Properties of 1-D Digital System : A digital system can be defined as an operator which transforms an input sequence { x(n)} to an output sequence {y(n)} A system of this type is said to be linear, … (Read More)

Frequency Domain Representation: A very important representation of discrete time systems can be obtained in terms of sinusoidal or complex-exponential signals. This is possible because the linear shift invariant systems have the interesting property that the response to … (Read More)

Fast Fourier Transform Formula: The Fast Fourier Transform Formula is a computational tool which facilitates signal analysis, such as power spectrum analysis and filter simulation using digital computers. In digital analysis of signals, the continuous waveform to be analysed is first sampled … (Read More)

FIR 1-D Digital Filter Design (The Window Method): We describe the Fourier series technique as the first design method of 1-D FIR digital filters . In this Digital Filter Design Window Method, given a frequency function H(ejω) with period 2π, an … (Read More)

IIR Digital Filter Design Methods: Fettveis first suggested the use of one port reflection coefficients for the tran­fer of analog filter properties from the analog domain to the digital filter domain, and thus produced the … (Read More)

IIR Filter Design 1-D: In this section some practical considerations relating to the methods for the design of IIR Filter Design filters are presented. In particular, the bilinear transform is considered along with its application to the digitization of rational transfer … (Read More)

Digital Filtering Processor: The implementation of any digital filtering consists of a series of multiplications of samples of the input and/or output signals by constants, and of the additions of these products. Thus the main building blocks which have to be … (Read More)

Typical Digital Filtering Operations: Digital filters in fact can be applied in many different parts of a signal and image processing transmission system. Two typical examples of systems in which Typical Digital Filtering Operations can be inserted are Local digital processing systems … (Read More)

Bandpass Analysis: There exist many practical situations in which multiple filtering and band pass analysis are required. In multiple filtering, one specific operation (for example low pass, high pass, band pass, etc.) is required to be performed on many signal channels … (Read More)

Modern Radar Systems Analysis: Modern Radar System are of great importance for both military and civil applications. The main problem of a typical radar system is the detection of return pulses; this substantially corresponds to determining the presence or absence of a … (Read More)

CT Scan Working Principle: Biomedicine is one area in which the use of digital signal processing techniques had had great impact. Computer tomography A recent advance in diagnostic analysis is represented by computer tomography (CT) scanning. While in … (Read More)

Recursive and Non Recursive Realisation: In recursive realisations, the present output value depends on the input (past and present values), as well as the previous value of the output. It can usually be recognized by the presence of both a and … (Read More)