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There are many types of band pass filter circuits are designed. Let’s explain the major types of filter circuits in detail.

Active Band Pass Filter

The active band pass filter is a cascading connection of high pass and low pass filter with the amplifying component as shown in the below figure.

Block Diagram of Active Band Pass Filter

The circuit diagram of Active Band Pass Filter is divided into three parts. The first part is for a high pass filter. Then the op-amp is used for the amplification. The last part of the circuit is the low pass filter. The below figure shows the circuit diagram of Active Band Pass Filter.

Circuit Diagram of Active Band Pass Filter

Passive Band Pass Filter

The passive filter used only passive components like resistors, capacitors, and inductors. Therefore, the passive band pass filter is also used passive components and it does not use the op-amp for amplification. So, like an active band pass filter, the amplification part is not present in a passive band pass filter.

The passive band pass filter is a combination of passive high pass and passive low pass filters. Hence, the circuit diagram also contains circuits of high pass and low pass filters.

Circuit Diagram of Passive Band Pass Filter

The first half of the circuit is for the passive high pass filter. And the second half is for the passive low pass filter.

RLC Band Pass Filter

As the name suggests RLC, this band pass filter contains only resistor, inductor and capacitor. This is also a passive band pass filter.

According to the connection of RLC, there are two circuit configurations of the RLC band pass filter. In the first configuration, the series LC circuit is connected in series with the load resistor. And the second configuration is parallel LC circuit is connected in parallel with a load resistor.

Circuit Diagram of RLC Band Pass Filter

The bandwidth for the series and parallel RLC band pass filter is as shown in the below equations.

Bandwidth for series RLC filter

The equation of corner frequency is the same for both configurations and the equation is

Bandwidth for parallel RLC filter

Wide Band Pass Filter

According to the size of bandwidth, it can divide into a wide bandpass filter and a narrow bandpass filter. If the Q-factor is less than 10, the filter is known as a wide pass filter. As the name suggests, the bandwidth is wide for the wide bandpass filter.

In this type of filter, the high pass and low pass filter are different sections as we have seen in the passive band pass filter. Here, both filters are passive.

Another circuit arrangement can be done by using an active high pass and an active low pass filter. The circuit diagram of this filter is as shown in the below figure where the first half is for active high pass filter and the second half is for active low pass filter.

Circuit Diagram of Wide band Pass Filter

Because of the different parts of filters, it is easy to design the circuit for a wide range of bandwidth.

Narrow Band Pass Filter

The band pass filter which has a quality factor greater than ten. The bandwidth of this filter is narrow. Therefore, it allows the signal with a small range of frequencies. It has multiple feedback. This band pass filter uses only one op-amp.

This band pass filter is also known as multiple feedback filter because there are two feedback paths.

In this band pass filter, the op-amp is used in non-inverting mode. The circuit diagram of band pass filter is as shown in the below figure.

Circuit Diagram of Narrow Band Pass Filter

Below figure differentiate the frequency response between wide pass and narrow pass filter.

Frequency Response of Wide Band Pass and Narrow Band Pass Filter