Passive band pass filter

What is a band pass filter? 

A bandpass filter is an electronic circuit that allows a specific range of frequencies to pass through while attenuating frequencies outside that range. It is commonly used in audio and radio frequency applications to selectively filter out unwanted frequencies and isolate the desired signal. 

Reference: https://eepower.com/technical-articles/how-to-create-bandpass-filters/# 

1.     Passive Low Pass Filter

Figure 1. Passive Low Pass Filter at https://www.electronics-tutorials.ws/filter/filter_2.html

Circuit for passive low pass filter

·         Cut-off Frequency and Phase Shift

2.     Passive High Pass Filter

 

Figure 2. Passive High Pass Filter at  https://www.electronics-tutorials.ws/filter/filter_3.html

·         Circuit for passive high pass filter

·         Cut-off Frequency and Phase Shift

3.     Passive Band Pass Filter

 

Figure 3. Reference source for passive band pass filter design: https://www.electronics-tutorials.ws/filter/filter_4.html

·         Circuit for band pass filter

·         Formula for capacitors and resistors

C₁ = 1 / 2πf_LR

C₂ = 1 / 2πf_HR

As shown in the figure 5 above, the signals with frequencies between f_L and f_H will be allowed to go through in an electronic circuit for further processing. Signals falling outside of this range would be attenuated or died out.

This passive band pass filter circuit is a common circuit in many electronic circuit boards to eliminate signal noise. The circuit consists of resistors and capacitors; thus, designers could refer to the web pages above to calculate required values of those components based on required cut off frequencies.

Another article shows how to calculate components and design a passive band pass filter: https://www.electronicshub.org/passive-band-pass-rc-filter/

List of filters with calculations and explanations: https://www.electronicshub.org/filters/