FCom Fuji Crystal · FSF-5050 Series · IF SAW Filter
280 MHz & 285 MHz IF SAW Filters
FSF-5050-280M · FSF-5050-285M
Two frequency options for receiver IF filtering in a 5.0 × 5.0 mm SMD package. Select by center frequency, specified signal band and matching network.
Two Frequencies · Model-Specific Matching
Choose the filter for your IF band
Both models specify loss and ripple over Fc ±4 MHz. Their typical 3 dB bandwidths and matching components differ; use the network and limits for your selected model.
IF SAW Filter · 280 MHz
FSF-5050-280M
280.0 MHz · typ.
3 dB BW: 12.5 MHz typ. · minimum 8.0 MHz
- Specified interval for IL and ripple
- 276–284 MHz
- Insertion loss
- 3.0 dB typ. / 4.5 dB max.
- Amplitude ripple
- 0.8 dB typ. / 2.0 dB max.
- Matching (each port)
- 9 pF series C + 47 nH shunt L
- Operating temperature
- −10 to +50 °C
IF SAW Filter · 285 MHz
FSF-5050-285M
285.0 MHz · typ.
3 dB BW: 12.0 MHz typ. · minimum 8.0 MHz
- Specified interval for IL and ripple
- 281–289 MHz
- Insertion loss
- 2.5 dB typ. / 4.5 dB max.
- Amplitude ripple
- 1.2 dB typ. / 2.0 dB max.
- Matching (each port)
- 8.2 pF series C + 40 nH shunt L
- Operating temperature
- −10 to +50 °C
Check the bandwidth definition. The 8 MHz interval over which IL and ripple are specified is separate from the measured 3 dB bandwidth. For 280M, the 3 dB points are relative to the minimum passband loss, ILmin; the 285M document cites JIS C6703 for measurement definitions.
Six Key Selection Parameters
Electrical specifications
Read insertion loss and amplitude ripple over each model’s stated frequency interval. The specifications use 50 Ω source and load with the model-specific matching network described below.
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FSF-5050-280M
| Parameter | Min. | Typ. | Max. | Unit | Definition / condition |
|---|---|---|---|---|---|
| Center frequency | — | 280.0 | — | MHz | Typical value. No frequency-tolerance limits are added. |
| Specified interval for IL and ripple | 276–284 | MHz | Fc ±4 MHz. Interval over which insertion loss and amplitude ripple are specified. The endpoints are range boundaries, not Min./Max. limits. | ||
| 3 dB bandwidth | 8.0 | 12.5 | — | MHz | Minimum is a specified limit; typical is for design guidance. Referenced to ILmin +3 dB, not a 0 dB absolute reference. |
| Insertion loss | — | 3.0 | 4.5 | dB | Over 276–284 MHz with 50 Ω source/load and the 280M matching network. |
| Amplitude ripple | — | 0.8 | 2.0 | dB | Over 276–284 MHz with 50 Ω source/load and the 280M matching network. |
| Operating temperature | −10 | — | +50 | °C | Operating range. Electrical-characteristic test temperature is not stated. |
FSF-5050-285M
| Parameter | Min. | Typ. | Max. | Unit | Definition / condition |
|---|---|---|---|---|---|
| Center frequency | — | 285.0 | — | MHz | Typical value. No frequency-tolerance limits are added. |
| Specified interval for IL and ripple | 281–289 | MHz | Fc ±4 MHz. Interval over which insertion loss and amplitude ripple are specified. The endpoints are range boundaries, not Min./Max. limits. | ||
| 3 dB bandwidth | 8.0 | 12.0 | — | MHz | Minimum is a specified limit; typical is for design guidance. Retain the source’s BW3dB designation and the JIS C6703 measurement reference. |
| Insertion loss | — | 2.5 | 4.5 | dB | Over 281–289 MHz with 50 Ω source/load and the 285M matching network. |
| Amplitude ripple | — | 1.2 | 2.0 | dB | Over 281–289 MHz with 50 Ω source/load and the 285M matching network. |
| Operating temperature | −10 | — | +50 | °C | Operating range. Electrical-characteristic test temperature is not stated. |
Center frequencies are typical values; no frequency-tolerance limits are added. The electrical-characteristic test temperature is not stated. Typical values are for design guidance and do not become guaranteed limits throughout the operating range.
Complete stopband intervals and limits are in the combined product document. Both models specify absolute stopband attenuation relative to 0 dB; evaluate the stated limits at the required blocker frequencies and do not treat them as additional rejection relative to the passband loss.
Typical Applications
Band selection within the receiver IF path
Receiver IF filtering
Select the 280 MHz or 285 MHz model to match the receiver’s intermediate-frequency plan.
Channel-band selection
Assess wanted-signal loss and ripple over Fc ±4 MHz, with the required signal bandwidth defined separately.
Out-of-band rejection
Evaluate rejection before downstream IF amplification or conversion using the selected model’s stopband limits.
- IF source stage
- Input matching
- FSF-5050 SAW filter
- Output matching
- IF amplifier / converter
Illustrative signal path. Matching is included at both ports; this diagram does not specify component placement or a validated PCB circuit.
Integration Notes
Use the matching network for the selected model
The 50 Ω source/load test system is separate from the SAW device-port impedance. Check the actual source, load, component tolerances and PCB layout before finalizing the interface.
Source, load and matching network
50 Ω source and 50 Ω load.
FSF-5050-280M · each signal port: series 9 pF capacitor + shunt 47 nH inductor.
FSF-5050-285M · each signal port: series 8.2 pF capacitor + shunt 40 nH inductor.
Device-port impedance and maximum ratings
Device-port impedance is separate from the test terminations. 280M: not specified. 285M: both ports 150 Ω ∥ 0 pF at Fc.
Both models: RF input power 0 dBm max., DC voltage 5 V max., operating −10 to +50 °C, storage −40 to +85 °C. Maximum ratings are limits, not recommended operating targets.
The 285M impedance entry is the specified port model at the center frequency; it does not establish zero physical parasitic capacitance. “—” means not specified.
Package & Pin Assignment
5.0 × 5.0 mm SMD package
Shared package format for both FSF-5050 280M and 285M models.
5.0 × 5.0 mm · 1.5 mm maximum height · 8-pad SMD, no lead
These dimensions and pin functions apply to both models in the FCom document. Confirm pad orientation and the applicable footprint before PCB release.
The function table does not assign an unverified view orientation. For other pin configurations, contact FCom to discuss the requirement.
| Pin(s) | Function |
|---|---|
| 2 | Input / Output |
| 6 | Input / Output |
| 1, 3, 5, 7 | Ground |
| 4, 8 | Case Ground |
Selection and Design-In Support
Share your IF band and interface requirements
Include the selected frequency, passband endpoints, bandwidth definition, source/load requirements and operating temperature. Add sample quantity, estimated usage and blocker-frequency targets to support a model-specific discussion.
Confirm the complete ordering code and applicable specification with FCom before ordering.
Engineering Questions
Frequently asked questions
How does the 8 MHz specified interval relate to 3 dB bandwidth?
Insertion loss and ripple apply over Fc ±4 MHz: 276–284 MHz for 280M and 281–289 MHz for 285M. Each interval spans 8 MHz. Separately, both models specify a minimum 3 dB bandwidth of 8.0 MHz; typical values are 12.5 MHz for 280M and 12.0 MHz for 285M. The interval endpoints are not specified as measured 3 dB cutoff frequencies. For 280M, the 3 dB reference is ILmin; the 285M document cites JIS C6703 for measurement definitions.
Can I use the same matching components for both models?
The specified test networks differ. With 50 Ω source and load, 280M uses a series 9 pF capacitor and a shunt 47 nH inductor at each signal port; 285M uses a series 8.2 pF capacitor and a shunt 40 nH inductor at each signal port. Evaluate the selected network with the actual source, load and PCB layout before finalizing the design.
Does the 50 Ω test system mean the device ports are 50 Ω?
No. Source/load test impedance and device-port impedance are separate quantities. For 285M, both device ports are specified as 150 Ω in parallel with 0 pF at the center frequency. Device-port impedances are not specified for 280M. Keep the model-specific matching networks when interpreting the electrical data.
What input-power and temperature limits apply?
Both models have a maximum RF input power of 0 dBm and a maximum DC voltage of 5 V. Their operating temperature range is −10 to +50 °C; storage is −40 to +85 °C. Maximum ratings are limits, not recommended operating targets, and storage limits do not extend the operating range.
Are 280M and 285M direct replacements for each other?
Direct interchangeability is not established. The center frequency, specified loss/ripple interval, typical bandwidth, matching values and stopband frequency intervals differ. A shared 5.0 × 5.0 mm package does not establish equivalent electrical performance. Confirm the selected model, pin orientation and circuit interface before substitution.
What should I include in a technical inquiry?
Provide the selected model or center frequency, required passband and bandwidth definition, source/load requirements, operating temperature, sample quantity and estimated usage. Include blocker frequencies and rejection targets when relevant. Confirm the complete ordering code and applicable specification with FCom before ordering.