Types of Active Filters Butterworth, Chebyshev, Bessel and Elliptic filters. There are basically 4 types of active filters. They are butterworth, Chebyshev, Bessel and Elliptic filters. Butterworth Filter: This filter is also called as maximally flat or flat flat filter. This class of filters approximates the ideal filter well in the pass band. Frequency response curves […]
With the advancement in IC technology, a number of manufacturers now offer universal filters having simultaneous low-pass, high-pass, and band-pass output responses. Notch and all-pass functions are also available by combining these output responses in the uncommitted op-amp. Because of its versatility, this filter is called the universal filter. It provides the user with easy
An all-pass filter is that which passes all frequency components of the input signal without attenuation but provides predictable phase shifts for different frequencies of the input signals. The all-pass filters are also called delay equalizers or phase correctors. An all-pass filter with the output lagging behind the input is illustrated in figure. The
The bandpass filÂter passes one set of frequenÂcies while rejectÂing all others. The band-stop filter does just the opposite. It rejects a band of frequencies, while passing all others. This is also called a band-reject or band-elimination filter. Like bandÂpass filters, band-stop filters may also be classified as (i) wide-band and (ii) narrow band reject
Band Pass Filter A band-pass filter is a circuit which is designed to pass signals only in a certain band of frequencies while attenuating all signals outside this band. The parameters of importance in a bandpass filter are the high and low cut-off frequencies (fH and fl), the bandwidth (BW), the centre frequency fc, centre-frequency
Higher Order Filters From the discussion made so far on the filters, it may be concluded that in the stopband the gain of the filter changes at the rate of 20 db/decade for first-order filters and 40 db/decade for second-order filters. This means that as the order of the filter is increased, the actual stopband
In many low-pass filter applications it is necessary that the closed-loop gain is as close to unity as possible within the passband. The Butterworth filter is best suited for such applications. This filter is also called a maximally flat or flat-flat filter. Ideal and the practical frequency responses for three types of Butterworth low-pass filters
The most widely used active filters are (i)Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â low-pass (ii)Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â high-pass (iii)Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â band-pass (iv)Â Â Â Â Â Â Â Â Â Â Â Â Â Â band-stop or band reject (also called the band-elimination or notch) and (v)Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â all-pass filters. All of these filters use op-amps as the active elements and R-C networks. Although the 741 type op-amp operates satisfactorily in these filter circuits, highÂ-speed op-amps like
Active and Passive filters – A Comparison: The simplest approach to building a filter is with passive components (resistors, capacitors, and inductors). In the R-F range it works quite well but with the lower frequencies, inductors create problems. AF inductors are physically larger and heavier, and therefore expensive. For lower frequencies the inductance is to
Introduction to Filters An electric filter is a network designed to attenuate certain frequencies but pass others without attenuation. A filter circuit, therefore, possesses at least one pass band — a band of frequencies in which the output is approximately equal to the input (that is, attenuation is zero) and an attenuation band in which
Series Inductor Filter. In this arrangeÂment a high value inductor or choke L is connected in series with the rectifier element and the load, as illustrated in figure. The filtering action of an inductor filter deÂpends upon its property of opposing any change in the current flowing through it. When the output
The drawbacks of pi-filters are the comparatively larger cost, more weight, bigger size and external field developed by the series inductor. However, these drawbacks can be overcome by replacing the series inductor by a series resistor R. Such a circuit is called the R-C filter circuit and is given in figure. By deliberate design R
A simple series inductor reduces both the peakand effective values of the output current and output voltage. On the other hand a simple shunt capacitor filter reduces the ripple voltage but increases the diode current. The diode may get damaged due to large current and at the same time it causes greater heating of supply
Shunt Capacitor Filter and types of it: This is the most simple form of the filter circuit and in this arrangement a high value capacitor C is placed directly across the output terminals, as shown in figure. During the conduction period it gets charged and stores up energy to it during non-conduction period. Through this process,
We have learnt in rectifier circuits about converting a sinusoidal ac voltage into its corresponding pulsating dc. Apart from the dc component, this pulsating dc voltage will have unwanted ac components like the components of its supply frequency along with its harmonics (together called ripples). These ripples will be the highest for a single-phase half
