FSF-5050-420M~427M8 IF SAW Filters 420–427.8MHz

Product Overview: 420–427.8 MHz 5×5 mm IF SAW Filter Family

FSF-5050-420M~427M8 is a 5.0×5.0 mm IF SAW filter family from FCom Fuji Crystal, optimized for ~400 MHz IF applications. It includes multiple closely spaced center frequencies at 420 MHz, 423.75 MHz, 424 MHz, 426.1 MHz and 427.8 MHz. By combining single-ended and differential interfaces in the same 5×5 platform, RF engineers can tune IF frequency, bandwidth and topology without changing the PCB footprint.

FSF-5050-420M, FSF-5050-423M75, FSF-5050-424M and FSF-5050-426M1 target 50 Ω single-ended IF chains with low insertion loss and strong stopband attenuation. FSF-5050-427M8 adds a 200 Ω balanced-to-balanced differential interface with wider IF bandwidth, ideal for systems that emphasize common-mode rejection, dynamic range and robust interference immunity.

At a glance: 420M (420 MHz, 50 Ω SE), 423M75 (423.75 MHz, 50 Ω SE), 424M (424 MHz, 50 Ω SE), 426M1 (426.1 MHz, high-selectivity narrow IF), 427M8 (427.8 MHz, 200 Ω differential).

Target Systems & Typical IF Placement

Target Systems

Telemetry and remote control receivers using ~400 MHz IF architectures
Industrial wireless / SRD-style radios requiring strong adjacent rejection
Receiver front ends sensitive to blocker-driven compression and intermodulation

Typical IF Placement

Post-mixer IF bandpass filtering to define channel mask and image suppression
Between IF gain stages to improve dynamic range by limiting out-of-band energy
In differential IF chains (427M8) to leverage common-mode rejection

Key Features

Unified 5.0×5.0 mm SMD package with SM5050 pad layout for platform designs.
Multiple 420–427.8 MHz IF points for flexible IF planning and standards alignment.
50 Ω single-ended and 200 Ω differential interfaces for mixed receiver architectures.
Low insertion loss and high stopband attenuation for robust selectivity and sensitivity.
Controlled ripple / group delay behavior to support modulation quality and spectral masks.
Lead-free, RoHS-compliant package compatible with standard reflow processes.

Typical Applications

Narrowband and wideband 400 MHz wireless IF bandpass filtering.
IF filtering for telemetry / remote control modules in industrial environments.
ISM band data transceivers and wireless sensor node RF/IF front ends.
IF channel selection in measurement instruments and RF front end modules.
System stacks combining SAW filters + timing devices (TCXO/VCXO/OCXO) for overall RF integrity.

Key Specs (Quick View)

Test conditions vary by part number; use the datasheet limits and S-parameter files for final design validation.

Frequency Options

420 / 423.75 / 424 / 426.1 / 427.8 MHz

Interfaces

50 Ω single-ended, 200 Ω differential (balanced-to-balanced)

Package

5.0×5.0 mm SMD (SM5050 footprint)

Supply Model

Samples, volume production, and customization support via RFQ

Detailed Specifications: FSF-5050-420M / 423M75 / 424M / 426M1 / 427M8

The following table summarizes representative electrical parameters for initial device selection. For guaranteed production limits and test conditions, refer to the latest official datasheets and S-parameter files.

Part Number	Center Frequency Fc (MHz)	Interface & Impedance	Passband / Bandwidth (Representative)	Insertion Loss IL (Typ / Max, dB)	Max Input Power (dBm)	Recommended Operating Temp (°C)
FSF-5050-420M	420	50 Ω single-ended input / output	~18–21 MHz (2 dB passband), suited for medium-bandwidth IF applications	~1.4 / ≤ 2.8	10	0 to +50
FSF-5050-423M75	423.75	50 Ω single-ended input / output	Approx. 421.5–426 MHz passband, suitable for wide IF and multi-channel systems	~2.0 / ≤ 3.5	15	−40 to +85
FSF-5050-424M	424	50 Ω single-ended input / output	~18–21.4 MHz (2 dB passband), similar to FSF-5050-420M	~1.4 / ≤ 2.8	20	0 to +50
FSF-5050-426M1	426.1	50 Ω class with matching recommended	Very narrow passband (~0.138 MHz), targeting high-selectivity IF/channelized designs	~2.5 / ≤ 3.5	10	−10 to +60
FSF-5050-427M8	427.8	200 Ω differential (balanced-to-balanced)	Approx. 5 MHz wide IF passband	~2.05 / ≤ 3.6	10	+15 to +35 (typ. controlled environments)

Note: Values are representative for comparison. Always validate your chain with the latest datasheet limits and S-parameter files.

Matching & Integration Notes: Single-Ended and Differential IF Chains

The FSF-5050-420M~427M8 family lets you adjust IF frequency, bandwidth and interface while preserving a common 5×5mm footprint. Use the following guidance to reduce re-spin risk and to improve first-pass RF performance:

50 Ω single-ended IF chains: 420M / 423M75 / 424M are typically placed between 50 Ω mixers and IF amplifiers. Add minimal LC matching only when measurement or simulation indicates return-loss or ripple issues.
High selectivity narrowband IF: 426M1 is intended for channelized architectures and demanding image/adjacent suppression. Matching networks are commonly used to optimize return loss and to control passband shape.
200 Ω differential IF chains: 427M8 is designed for differential IF amplifiers and balanced front ends. In 50 Ω systems, use a balun plus matching to convert SE↔diff and validate group delay/ripple against your demod/EVM target.
Layout fundamentals: Keep RF traces short and symmetric where applicable, use a solid ground plane with via fences, and avoid unnecessary test pads or ESD structures directly on RF nodes unless validated.

For practical selection and integration references, see: How to Choose the Optimal SAW Filter for Your System and SAW Filter PCB Layout & ESD Design in Practice.

Ordering Code / Options

Select the part number primarily by IF center frequency and interface type. For production qualification, also confirm operating temperature, bandwidth mask, and any screening/packaging requirements during RFQ.

Frequency options: 420 / 423.75 / 424 / 426.1 / 427.8 MHz
Interface options: 50 Ω single-ended (420M/423M75/424M/426M1) and 200 Ω differential (427M8)
Temperature grade: confirm per part number and application environment
Customization: frequency, bandwidth shaping, impedance/interface, temperature range (subject to feasibility review)

Selection Path / Upgrade Options: If your IF plan shifts or you need nearby center frequencies within the same 5×5 footprint, review: FSF-5050 Family Overview, FSF-5050-413M~415M4, FSF-5050-433M~435M, FSF-5050-440M~446M.

Documents & Downloads

Datasheets (PDF)

Tip: Use the datasheet limits plus S-parameter simulation to validate insertion loss, ripple and group delay vs. your receiver mask.

Package Outline

Outline image for footprint planning and documentation.

Frequently Asked Questions (FAQ)

Q1: How should I choose between FSF-5050-420M, 423M75, 424M, 426M1 and 427M8?

A: Choose 420M / 423M75 / 424M for 50 Ω single-ended IF chains based on your IF plan and channel mask. Use 426M1 when you need a very narrow, high-selectivity IF passband. Choose 427M8 when your design uses a 200 Ω balanced-to-balanced differential IF path and you want strong common-mode rejection with wide IF bandwidth.

Q2: Can the 200 Ω differential FSF-5050-427M8 work in a 50 Ω single-ended system?

A: Yes. Use a balun plus a matching network to convert 50 Ω single-ended to 200 Ω differential, or interface the filter directly to a suitable differential IF amplifier. Keep the balun/matching close to the filter pads and verify insertion loss, return loss and group delay with S-parameter simulation and VNA measurements.

Q3: Do you provide samples, and what are typical MOQ and lead time?

A: Yes—samples are available for evaluation. MOQ and lead time depend on the exact part number, screening and packaging. Please send your target frequency, bandwidth and operating temperature to request an RFQ with MOQ and lead time.

Q4: Do you support customization (frequency, bandwidth, impedance, temperature grade)?

A: Yes. For projects requiring a specific IF frequency, bandwidth shape, impedance/interface, or temperature range, FCom can review requirements and propose a customized SAW filter solution. Contact technical support with your system block diagram and target mask.

Q5: Why is there no list price, and how do I request pricing?

A: These are B2B components and pricing depends on volume, specs, qualification and delivery terms. Submit an RFQ via Contact with part number(s), estimated annual volume and required documentation to receive a formal quotation.

Q6: Can you provide packaging details and quality certificates?

A: Yes. We can provide packaging information and supporting quality documentation upon request. FCom operates ISO9001 and ISO14001 management systems; references are available via ISO9001 and ISO14001.

Request RFQ / Samples / Technical Support
For samples, volume supply, customization review, or the latest S-parameter support, contact FCom Fuji Crystal: Contact Us or submit details via Online Inquiry. You can also email Fcom@fujicrystal.com with your target IF, bandwidth mask, interface (50 Ω SE / 200 Ω diff), operating temperature, and estimated volume.

FSF-5050-420M~427M8 IF SAW Filter Series