RF Band Pass Filters are high frequency filters that are used to block unwanted signals in the wireless system. Band pass filters have a center frequency and a bandwidth, they only allow signals which lie within the specified bandwidth to pass through. Signals outside this bandwidth are attenuated considerably.  A band pass filter can be thought of as a combination of low pass and high pass filters and has two cut-off frequencies. The first cut-off frequency is taken from the high pass filter, that gives the higher frequency limit of the passband band. Similarly, the second cut-off frequency is from the low pass filter which determines the lower limit of the passband.

Bandpass filters are widely used in wireless transmitters and receivers for removing unwanted/noise signals.

Important parameters to consider when looking for Bandpass Filters:

● Type: There are many types of BPF filters - SAW, Cavity, Notch, and Ceramic. The type is normally selected based on the application and configuration of the required system.

● Passband (MHz/GHz): Passband it the frequency range that the BPF allows to pass through it with minimal attenuation. Any frequency above or below the passband will be heavily attenuated. Passband can also be specified with center frequency and the bandwidth.

● Insertion Loss (dB): It is the reduction in output power due when a BPF is introduced in the circuit. The lower the insertion loss, the better is the performance of the filter.

● Input Power Handling (dBm/W): It is the magnitude of input power that the BPF can handle while maintaining its electrical characteristics.

● Return Loss (dB): Return loss is a parameter to evaluate the filter performance characteristic providing the relative amount of power reflected from load.