250+ TOP MCQs on Active Filters and Answers Online Quiz MCQs and Answers

The frequencies that separate the different pass and attenuation bands are called the cut-off frequencies. This filter allows the frequencies of a signal in a particular range i.e., above and below the cut-off frequency. The stopband represents the attenuated frequencies, ranges between the two cut-off frequencies.

TOP MCQs on Active Filters and Answers Online Quiz

• The Frequency response of a practical low pass filter, when it works as an Integrator is as shown below.
• The low pass filter allows the frequencies below its cut-off frequency while the high pass filter allows the frequency above its cut-off frequency.
• While the two passbands the frequencies below and above the cut-off frequencies of low pass and high pass filter circuits.

Since the circuit does not allow the input to pass, the output voltage will be 0 V. According to the operating frequency range, the filters may be classified as audio ­frequency (AF) or radio-frequency (RF) filters. The filter that performs the opposite to the band-pass filter is the band-reject filter, as stated in option a. Hence, a resistor of 4kilo ohms is required to design the RC bandstop filter with 120Hz center frequency and 0.33 micro Farads capacitance. Find the resistance required for an RC band stop filter with a center frequency of 120Hz and, the capacitance of 0.33micro farads.

Band Stop Filter Design

The ideal characteristics of the band-stop filter, which are opposite characteristics of band pass filter are shown below. The frequency response of the band stop filter is shown in the below figure. The frequency response of an ideal band stop filter is shown in fig. Hence a LPF with large time constant produces an output that is proportional to the integral of an input.

The passband gain of this filter should be equal to the gain of the low pass and high pass filter. The bandwidth of the band pass filter is therefore, equal to fc2-fc1, where fc1 and fc2 are lower and higher cutoff frequencies respectively. The frequency response of an ideal band pass filter is shown in fig.

Band Stop Filters Question 5

The type of elements used dictates the operating frequency range of the filter.. Electrical filters are used in practically all circuits which require separation of signals according to their frequencies. The band stop or band reject filter performs exactly opposite to the band pass filter. The high pass filter has a zero gain starting from zero to a frequency fc, called the cutoff frequency, and above this frequency, the gain is constant. The filter circuit may be so designed that some frequencies are passed from the input to the out­put of the filter with very little attenuation while others are greatly attenuated.

It is widely used to reject the specific frequency bands in reducing electrical noise, graphical equalizers, synthesizers, communications, biomedical applications, and many more. The input voltage is applied across the resistor and the output voltage is obtained across the inductor and the capacitor. This filter allows all the high and low-frequency components with respect to the cut-off frequency. At low-frequency range, the capacitor becomes an open circuit and the inductor becomes a short circuit. At the high-frequency range, the capacitor becomes a short circuit and the inductor becomes an open circuit.

The low pass filter allows the frequencies below its cut-off frequency while the high pass filter allows the frequency above its cut-off frequency. These two cut-off frequencies are predetermined based on the component values used in the circuit. The bandstop filter doesn’t allow the frequencies between these two cut-off frequencies and are attenuated or rejected. The final output from the high pass filter and low pass filter is amplified by using an operational amplifier (op-amp) to improve the voltage gain. The voltage gain i.e. the ratio of output voltage to input voltage is constant over a frequency range from zero to cutoff frequency fc. A notch filter is a band-stop filter with a narrow stopband (high Q factor).

• This filter is designed with the low pass filter and high pass filter, which are connected in parallel to allow high and low-frequency components.
• The output voltage Vout drops at the high frequency of the high pass filter and at a low frequency of the low pass filter.
• The passband gain of this filter should be equal to the gain of the low pass and high pass filter.
• The frequencies between fL and fH are attenuated, which represents the stopband.
• Depending on the type of techniques used in the process of analog signals the filters may be analog or digital.

Basic Filter Effects

The filter is sometimes called a high-cut filter, or treble-cut filter in audio applications. The band stop filter theory can be understood by using the block diagram shown below. The frequencies between fL and fH are attenuated, which represents the stopband.

It allows all the frequencies below and above the cut-off frequency of low pass and high pass filter circuit. Since which filter performs exactly the opposite to the band-pass filter this circuit is designed using low pass and high pass filter circuits. This type of filter is mainly used to reduce the distortion in the signal. The band stop filter is a type of frequency selective circuit, that works exactly opposite to the bandpass filter. The name itself shows that it stops or rejects the particular range of frequencies of a signal. This filter is designed with the low pass filter and high pass filter, which are connected in parallel to allow high and low-frequency components.

In our next articles we will study about each type of passive and active filters in detail. Filters may be of any type such as electrical, mechanical, pneumatic, hydraulic, acous­tical etc. but the most commonly used filters are of the electrical type. Now that we have looked at what filters do to an audio signal, let’s look at how they can be created. Hence,the output will be available faithfully from 0 to fc with constant gain.

Band Stop Filters Question 1 Detailed Solution

It blocks the frequency components between the low and high-frequency ranges. When the input signal is applied, the high frequencies are passed through a high pass filter and low frequencies are passed through a low pass filter. The output voltage Vout drops at the high frequency of the high pass filter and at a low frequency of the low pass filter. These two filters are connected in parallel to allow all the high and low frequencies of a signal without any obstruction. The range of frequencies between the fL and fH is attenuated. An electric filter is a network designed to attenuate certain frequencies but pass others without attenuation.

The band stop filter allows frequency components below the cut-off frequency and above the cut-off frequency. The cut-off frequency of the low pass filter is denoted as fL and the cut-off frequency of the high pass filter is denoted as fH. As the band stop filter contains two cut-off frequencies for low and high-frequency ranges, it depends on the components used in the circuit. This article gives a complete description of the band stop filter.

A filter that provides a constant output from dc upto a cut-off frequency fc and then passes no signal above that frequency is called an ideal low-pass filter. The ideal response of a low-pass filter is illustrated in fig. The filter that allows above and below the particular range of frequencies and rejects all other frequencies of a given input signal, is known as band stop filter. It is also known as a band-reject filter or band elimination filter or notch filter.

How does an LPF work as an integrator?

While the two passbands the frequencies below and above the cut-off frequencies of low pass and high pass filter circuits. When the filter circuit passes signals that are above one cutoff frequency and below a second cutoff frequency, it is called a band pass filter. A filter that provides or passes signals above a cut-off frequency is a high-pass filter, as idealized in fig.b. The high-pass filter has a zero gain starting from zero to a frequency fc, called the cut-off frequency, and above this frequency, the gain is constant, as illustrated in fig. Thus signal of any frequency beyond fc is faithfully reproduced with a constant gain, and frequencies from 0 to fc will be attenuated.

This filter passes all frequencies equally well, i.e., output and input voltages are equal in amplitude for all frequencies. The important feature of this filter is that it provides predictable phase shift for frequencies of different input signals. This filter allows a particular range of frequencies, which are above and below the cut-off frequencies of high pass and low pass filter circuits.