In modern wireless communication systems, miniaturized MMIC microwave bandpass filters are required to reduce the cost and decrease the RF system design time, especially for a single RF transceiver chip. (MicroWave Journal)

Two-way signal splitting and combining to define the two channels may be performed with in-phase splitters and combiners, for example, or diplexer circuits, each composed of two bandpass filters with different characteristics but overlapping frequency responses and preferably approximately equal center frequencies. (Defence Technical Information Center)

Design a bandpass filter that will yield a resonant frequency of 10 kHz, with a maximum gain of 10, and a bandwidth of no more than 500 Hz. (The MathWorks)