RF filter innovations in compact systems
As RF systems become smaller and more densely integrated, designers face a familiar engineering challenge. In particular, they must reduce component size without sacrificing the electrical performance that made the original design successful.
Mini-Circuits has addressed that trade-off with a new generation of ceramic resonator bandpass filters. This approach benefits the RF filter by reducing size by about 45 to 60 percent while improving RF characteristics.
The new CBP2 family represents a redesign of established Mini-Circuits ceramic resonator filters rather than simply repackaging existing devices. Advances in filter design, tuning, and manufacturing technology allow filters to use available volume more efficiently while maintaining—and, in key areas, improving—RF performance.
The result is a family aimed at applications where PCB area, system volume, and filtering performance are all at a premium, including defense and military electronics, aviation, aeronautical radio navigation, test and measurement, Bluetooth and LAN systems.
More Performance from Less Volume
Miniaturizing an RF filter presents challenges, since smaller dimensions affect resonator behavior, coupling, insertion loss, and selectivity. Mini-Circuits’ development effort focused not only on reducing package dimensions, but also on improving energy transfer through the filter. It also provides tighter control over filter characteristics.
The redesigned products offer lower insertion loss for improved signal transmission efficiency, stronger close-in rejection to suppress adjacent-channel interference, higher out-of-band attenuation, and sharper selectivity. Improvements in manufacturing processes and tighter production controls also provide greater consistency from unit to unit.
These characteristics are important at the system level. Lower passband loss helps preserve link budget, while improved rejection reduces the level of unwanted signals reaching downstream components. Achieving both in a substantially smaller package gives designers more flexibility in increasingly space-constrained RF assemblies.
Smaller with Improved Rejection
One example is the CBP2-2250CC+, a 2000 to 2500 MHz bandpass filter developed as the next-generation version of the CBP-2250A+. The new filter measures only 0.6 × 0.5 × 0.12 in., compared with 1.04 × 0.55 × 0.185 in. for the previous product.
The CBP2-2250CC+ provides typical insertion loss of 1.2 dB and typical return loss of 16 dB. Its combination of compact size and broadband filtering performance makes it suitable for defense and military electronics, aviation, and test and measurement systems.
Figure 1. Broadband insertion-loss comparison of the CBP2-2250CC+ and previous-generation CBP-2250A+ (a) and zoomed-in insertion loss comparison (b).
The broadband response shows that miniaturization has not been achieved by simply accepting reduced rejection performance. The CBP2-2250CC+ maintains a well-defined 2-2.5 GHz passband while exhibiting good attenuation outside the operating band.
A second example, the CBP2-2400CC+, covers 2200 to 2600 MHz and provides just 1.1 dB typical insertion loss with 16 dB typical return loss. It uses the same 0.6 × 0.5 × 0.12 in. package and is intended for applications including test and measurement, Bluetooth and LAN equipment.
High Rejection in an Even Smaller Package
The size reduction is particularly evident in the CBP2-1350CR+. Designed for a 1300 to 1400 MHz passband, the filter measures just 0.39 × 0.47 × 0.11 in., compared with 0.75 × 0.75 × 0.21 in. for the CBP-1350C+ it replaces.
Despite this reduction, the new design provides a typical insertion loss of 1.2 dB and a typical rejection of 55 dB. Applications include aeronautical radio navigation and defense and military systems, where strong rejection of unwanted signals can be critical.
Figure 2: Broadband insertion-loss comparison of the CBP2-1350CR+ and CBP-1350C+, illustrating the passband and out-of-band rejection characteristics.
The response comparison demonstrates the design philosophy behind the new family: use miniaturization as an opportunity to improve the filter rather than simply shrink it. The CBP2-1350CR+ exhibits a sharply defined passband together with substantial attenuation outside the desired frequency range.
Extending the Approach Across the Portfolio
Mini-Circuits is applying the same architecture to additional frequency ranges. The CBP2-1630CS+ covers 1500 to 1760 MHz with a typical insertion loss of 1.2 dB and a typical rejection of 50 dB. The CBP2-1820CS+ extends coverage from 1680 to 1960 MHz, with a typical insertion loss of 1.3 dB and a typical rejection of 50 dB. Both measure 0.58 × 0.45 × 0.12 in., a significant reduction from the 1.05 × 0.875 × 0.24 in. packages of their respective previous-generation models, the CBP-1630F+ and CBP-1820F+. Here is a list of the initial products that are released: Miniature Ceramic Resonator Filters. You can find all of the Mini-Circuits filters on the product page here: RF Filters – Bandpass Filter | Low-pass Filter | High-pass Filter | Band-stop Filter | Diplexers and Triplexers – Mini-Circuits.
The CBP2-2250CC+ is already available in the Mini-Circuits catalog. The CBP2-2400CC+ and CBP2-1350CR+ are planned for Q3 2026 release, followed by the CBP2-1630CS+ and CBP2-1820CS+ in Q4. For RF designers, the significance of the redesign goes beyond smaller components. By combining major reductions in physical volume with low insertion loss, stronger rejection and improved selectivity, the new generation of ceramic resonator filters can free valuable system space while preserving the RF performance required in increasingly dense and demanding systems.
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