RF Filters

Part Number	Description / PDF	Quantity
B259MC1S Knowles DLI	26.0GHZ SURFACE MOUNT BANDPASS F	0
B039NC5S Knowles DLI	RF FILTER 3.95GHZ BANDPASS 2SMD	0
H100XHXS Knowles DLI	RF FILTER HIGH PASS 10GHZ 2SMD	27
B274MB1S Knowles DLI	RF FILTER BANDPASS	71
L185XF4S Knowles DLI	LOW PASS FILTER	90
B116NC5S Knowles DLI	BANDPASS	58
B120MB1S Knowles DLI	RF FILTER BAND PASS 12GHZ 8SMD	184
B102MC1S Knowles DLI	BANDPASS	10
B138LA2S Knowles DLI	BANDPASS	10
B148LA2S Knowles DLI	BANDPASS	6
L117XH4S Knowles DLI	RF FILTER LOW PASS 11.7GHZ 6SMD	37
H080XHXS Knowles DLI	RF FILTER HIGH PASS 8GHZ 8SMD	9
B052NC5S Knowles DLI	RF FILTER 5.2GHZ BANDPASS 2SMD	22
L095XG9S Knowles DLI	RF FILTER LOW PASS 9.5GHZ 6SMD	173
B033ND5S Knowles DLI	RF FILTER BAND PASS 3.3GHZ 6SMD	6
B055NC5S Knowles DLI	RF FILTER 5.5GHZ BANDPASS 2SMD	53
B040MB5S Knowles DLI	RF FILTER 4GHZ BAND PASS 2SMD	0
AEQ05469-10 Knowles DLI	RF FILTER GAIN EQUALIZER 2SMD	680
B145LB1S Knowles DLI	BANDPASS	10
B065NC5S Knowles DLI	RF FILTER 6.5GHZ BANDPASS 2SMD	41

RF Filters

1. Overview

RF Filters are passive components that selectively allow or block specific frequency ranges in radio frequency (RF) systems. They are critical for signal integrity in wireless communication by eliminating interference, enhancing signal clarity, and ensuring compliance with regulatory standards. Modern applications include 5G networks, Wi-Fi systems, radar, and IoT devices.

2. Main Types and Functional Classification

Type	Functional Characteristics	Application Examples
Bandpass Filter	Allows frequencies within a specific range	Cellular base stations, Wi-Fi routers
Low-pass Filter	Passes frequencies below cutoff frequency	Power amplifiers, GPS systems
High-pass Filter	Attenuates frequencies below cutoff frequency	Satellite communication systems
Band-reject Filter	Blocks specific frequency bands	Medical imaging equipment
SAW Filter	Uses surface acoustic waves for precise filtering	Smartphones, automotive radar
BAW Filter	Employs bulk acoustic resonators for high-frequency operation	5G mmWave devices, WLAN modules
Cavity Filter	Metallic resonant cavities for high Q-factor	Radio astronomy, military communication

3. Structure and Components

Typical RF filter structures include:

Resonant Elements: Determine passband frequencies (e.g., quartz crystals in SAW filters)
Transmission Lines: Microstrip or coplanar waveguides for signal propagation
Dielectric Materials: Substrates like alumina or LTCC for impedance control
Enclosure: Metal housing for EMI shielding (cavity filters) or surface-mount packages
Ports: Input/output connectors (SMA, N-type) or PCB pads

Advanced designs integrate MEMS tuning mechanisms or LTCC multilayer structures for miniaturization.

4. Key Technical Specifications

Parameter	Description	Importance
Frequency Range	Operational bandwidth (e.g., 2.4-2.5 GHz)	Determines application compatibility
Insertion Loss	Signal attenuation in passband (e.g., <1.5 dB)	Impacts system sensitivity
Bandwidth (3dB)	Passband width at half-power points	Defines frequency selectivity
Rejection Ratio	Stopband attenuation level (e.g., >40 dB)	Interference suppression capability
Power Handling	Maximum input power (e.g., 20W CW)	Prevents component damage
Temperature Stability	Frequency drift vs temperature (e.g., 50 ppm/ C)	Ensures operational reliability

5. Application Fields

Telecommunications: 5G NR base stations, fiber optic networks
Aerospace: Avionics navigation systems, satellite transponders
Medical: MRI RF coils, ultrasound imaging equipment
Automotive: V2X communication modules, 77GHz radar systems
Industrial: Wireless sensor networks, RFID readers

6. Leading Manufacturers and Products

Manufacturer	Representative Product	Key Features
Murata Manufacturing	SAWLF5G30D	3.3-4.2 GHz BAW filter for 5G
Qorvo	QPM2515	2.3-2.7 GHz bandpass filter, 100W power rating
Skyworks Solutions	SKY13460	DC-6 GHz SPDT switch with integrated filters
Mini-Circuits	BFCN-1100+	Cavity filter with 1050-1300 MHz range
TE Connectivity	RFHF35-2.92M	High-frequency coaxial filter up to 40 GHz

7. Selection Guidelines

Key considerations:

Frequency Requirements: Match passband with system operating bands
Power Handling: Ensure ratings exceed maximum system power
Environmental Conditions: Temperature (-40 to +85 C), humidity resistance
Form Factor: SMD for compact designs vs. coaxial for high-power applications
Cost vs. Performance: Trade-off between ceramic filters (low-cost) and cavity filters (high-stability)

Case Study: Selecting a BAW filter for 5G mmWave devices requires <0.5 dB insertion loss, 28 GHz operation, and compliance with 3GPP TS 38.141-1 standards.

8. Industry Trends and Future Outlook

Key development trends:

Higher Frequency Operation: mmWave filters for 5G/6G (24-100 GHz) using photonic bandgap structures
Miniaturization: Wafer-level packaging reducing SAW filter size to 0.4x0.2 mm
Integrated Solutions: Filter+LNA modules for IoT devices (e.g., Qorvo's QM33013)
Advanced Materials: Lithium niobate on silicon (LiNoSi) substrates improving temperature stability
Software-Defined Radio: Tunable RF filters with MEMS or ferroelectric materials

The market is projected to grow at 9.8% CAGR (2023-2030), driven by automotive radar and satellite internet demand.