![]() The peak at which the output gain stays maximum is called as the resonant frequency. ![]() When the input frequency is less than the lower cut-off frequency (f-low) the output remains less than -3dB and when it exceeds that frequency, the output reaches the maximum and stays there until the frequency exceeds the higher cut-off frequency (f-high). ![]() The graph is plotted against the input frequency in the X-axis and the output in decibels in the Y-axis. The Frequency response a.k.a Bode Plot curve for a 2 nd order passive Bandpass filter is shown below. Hence the Bandwidth of the filter can be calculated by Bandwidth = fc HIGH- fc LOW ![]() In other words the output frequency can be given by fc HIGH- fc LOW, the frequency that lies in between this region is called as bandwidth. Now, when an input signal frequency is supplied to this filter it outputs a frequency which is higher than fc LOW and lower than fc HIGH. A band pass filter could be a 2 nd order filter or of higher order since a minimum of two resistor and capacitor is needed for proper functioning of the circuit. This type of filter circuit is called as 2 nd order filter because it has two resistors and two capacitors. The value of low cut-off frequency can be calculated using the formulae fc LOW = 1 / 2 π*R2*C2 The second half of the circuit is the Low-Pass filter circuit which filters the higher frequencies and allows only the frequency that is lower than the set low cut-off frequency (fc LOW). The value of this high cut-off frequency can be calculated using the formulae fc HIGH = 1 / 2 π*R1*C1 The first half of the circuit is a High-Pass filter which filters the low frequencies and allows only the frequency that is higher than the set high cut-off frequency (fc HIGH). A sample circuit diagram of a simple passive Bandpass filter is shown below. It is a combination of the high pass filter and low pass filter. Apart from this classification, the other aspects on which the filter can be classified, will be briefed in this article.Īs told earlier we will discuss the Passive Bandpass Filter which is constructed using resistor and capacitor. In this article we will discuss more on the passive bandpass filter. then the circuit is called as Active bandpass filter and if the circuit does not involve any active components and consists only passive components like resistor, capacitor and inductor then the circuit is called as Passive bandpass filter. If the circuit involves some kind of external source of power (active devices) like transistors etc. There are two types of band pass filters. It has a huge application in audio amplifier circuits and wireless transceivers where the speaker has to play only the desired set of frequencies and ignore the rest. A bandpass filter can be obtained by cascading both high and low pass filters. A filter that allows only the frequencies that are higher than it is called as high pass filter and the filter that allows the frequencies that are only lower than it is called as low pass filter. It is a combination of a high pass filter and a low pass filter. It will filter of all the frequency that is below the set value and above the set value. So in this tutorial, we will learn about this Band Pass filter, the theory behind it and how it can be used in practical circuits.Ī bandpass filter circuit/device is used to allow only a pre-defined set of frequencies to pass through it. There are many types of filter circuit, but the most commonly used and efficient one is the Band Pass Filter which can be easily constructed using a pair of resistor and capacitors. As the name suggests, this circuit will filter out the unwanted signals (noise) from the actual signal. Out of the many ways to remove noise from a circuit, the most used one is called a Filter Circuit. When it comes to switching circuits or Audio amplifiers or frequency signal circuits there is a very good chance for the circuit to be affected by noise signals. Every analog designer’s nightmare would be to deal with noise in his circuit.
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