Band Pass Filters

Posted on Feb 6, 2014

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 gain, and the selectivity or Q

Band Pass Filters
Click here to download the full size of the above Circuit.

. There are basically two types of bandpass filters viz wide bandpass and narrow bandpass filters. Unfortunately, there is no set dividing line between the two. However, a bandpass filter is defined as a wide bandpass if its figure of merit or quality factor Q is less than 10 while the bandpass filters with Q > 10 are called the narrow bandpass filters. Thus Q is a measure of selectivity, meaning the higher the value of Q the more selective is the filter, or the narrower is the bandwidth (BW). The relationship between Q, 3-db bandwidth, and the centre frequency fc is given by an equation For a wide bandpass filter the centre frequency can be defined aswhere fH and fL are respectively the high and low cut-off frequencies in Hz. In a narrow bandpass filter, the output voltage peaks at the centre frequency fc. A wide bandpass filter can be formed by simply cascading high-pass and low-pass sections and is generally the choice for simplicity of design and performance though such a circuit can be realized by a number of possible circuits. To form a ± 20 db/ decade bandpass filter, a first-order high-pass and a first-order low-pass sections are cascaded; for a ± 40 db/decade bandpass filter, second-order high- pass filter and a second-order low-pass filter are connected in series, and so on. It means that, the order of the bandpass filter is governed by the order of the high-pass and low-pass filters it consists of. A ± 20...

Leave Comment

characters left:

Related Circuits

  • New Circuits



    Popular Circuits

    Phone in Hold with Music
    200 Watt audio power amplifier
    Overtone crystal oscillator
    Light-Wave Voice-Communication Transmitter Circuit
    Digital Remote Thermometer
    water sensor alarm circuit using ic
    Simple Lightning Detector Circuit
    DC motor speed controller with 555 timer
    the Poppet 500 milliwatt AM transmitter
    Animation with Servos
    Low-pass filter circuit diagram subwoofer
    Pathfinder is one of the blind LM567 KD56022