SI4126-F-GM - 2.3 GHz RF Synthesizer | Skyworks
MPN: SI4126-F-GM ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $0 | $0.00 |
| 10 | $0 | $0.00 |
| 100 | $0 | $0.00 |
| 500 | $0 | $0.00 |
| 1,000 | $0 | $0.00 |
SI4126-F-GM Overview
A frequency synthesizer is a clock-and-timing building block that uses a phase-locked loop to create stable, programmable radio-frequency output signals. The broader hierarchy is RF synthesizer → frequency synthesizer → PLL/clock-generation IC → timing and RF integrated circuit. By generating an RF carrier or intermediate-frequency signal, this class of device supports wireless transmitters, receivers, modems, and ISM-band radio equipment.
The verified distributor data identifies a maximum RF output of 2.3 GHz, one output channel, a 2 MHz to 50 MHz input range, and a 28-pin QFN exposed-pad package. Additional manufacturer descriptions state that the SI4126 family integrates VCOs, loop filters, varactors, and resonators, requires minimal external components, provides low phase noise, draws 5 uA in standby, and typically consumes 25.7 mA from the supply. These characteristics can shorten RF board development by reducing discrete resonator and varactor assembly.
The device is intended for wireless communications in the industrial, scientific, and medical radio bands. A system designer can use its programmable synthesis function to establish an RF carrier for a transceiver chain, subject to the frequency plan, loop settings, reference requirements, and regulatory limits defined in the manufacturer datasheet. Its integrated frequency-setting elements also simplify BOM management compared with a discrete VCO implementation, although fixed external filtering, matching, and regulatory testing remain necessary.
PCB layout is a central design consideration because a phase-locked-loop synthesizer contains a high-frequency oscillator and sensitive feedback node. The exposed pad must be connected to the required ground plane, supply and return paths must be short, and RF output routing should use controlled-impedance geometry where applicable. The datasheet must be consulted for the complete recommended decoupling network, loop-filter values, reference sensitivity, package land pattern, exposed-pad connection, and operating limits.
This page consolidates the verified distributor descriptions, package information, sourcing links, and practical RF layout considerations. It intentionally avoids inventing missing electrical limits, pricing, pin names, or alternative parts; those details remain marked as data needed until confirmed from the manufacturer datasheet or a verified cross-reference.
The SI4126-F-GM is best evaluated when a wireless design benefits from a highly integrated ISM RF synthesizer and a compact exposed-pad package. Final design release requires reviewing the manufacturer datasheet for absolute maximum ratings, tuning range, lock-time behavior, phase-noise profile, control interfaces, recommended PCB land pattern, and regulatory implementation constraints.
Drop-in alternatives for SI4126-F-GM — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
No drop-in alternatives available for this product.
Request AlternativesSI4126-F-GM Specifications
| Product Type | ISM RF frequency synthesizer with integrated VCO |
| Maximum RF Output Frequency | 2.3 GHz |
| Number of Synthesizer Channels | 1 channel |
| Reference Input Frequency Range | 2 MHz to 50 MHz |
| Supply Current | 25.7 mA typical |
| Standby Current | 5 uA |
| Integrated RF Elements | VCO, loop filter, varactors, and resonators |
| External Component Requirement | Minimal external components required |
| Phase Noise | Low phase noise |
| Package | 28-pin VQFN exposed pad |
| Package Dimensions | 5 mm x 5 mm |
| Mounting Type | Surface mount |
| Operating Frequency Band | ISM RF band |
| Application Domain | Wireless communications |
| Device Classification | Clock generator, PLL, and frequency synthesizer IC |
| Exposed Pad | Present |
SI4126-F-GM 5 mm x 5 mm Pin Configuration Guide
Pin configuration for SI4126-F-GM (5 mm x 5 mm package). Pin numbering, functions, and connection diagrams are defined in the manufacturer datasheet. Refer to it for the exact footprint and soldering guidelines.
No detailed pinout data available for SI4126-F-GM.
Refer to the datasheet for full pin configuration.
Typical Applications
SI4126-F-GM is suitable for 6 applications: ISM-Band Wireless Transmitter, Wireless Receiver Local Oscillator, Frequency-Hopping Control, Industrial Sensor Link, Portable Wireless Endpoint, RF Test and Measurement Source.
ISM-Band Wireless Transmitter
The SI4126-F-GM fits an ISM-band transmitter front end that requires a programmable RF source with a listed output up to 2.3 GHz. Its integrated VCO, loop filter, varactors, and resonators can reduce the number of discrete frequency-setting components and simplify assembly. The designer still needs the manufacturer's loop-filter settings, control interface, reference requirements, and RF output conditions. A separate power amplifier and output network are normally required when the selected system power exceeds synthesizer output capability.
Wireless Receiver Local Oscillator
A wireless receiver can use the SI4126-F-GM as its local-oscillator source when the target system matches its listed single-channel, 2.3 GHz maximum RF capability. Integration of the VCO and associated tuning elements may shorten RF development compared with discrete resonator construction. Receiver performance still depends on phase noise, lock behavior, spur requirements, isolation from the RF input, and the IF or direct-conversion architecture described by the complete manufacturer documentation.
Frequency-Hopping Control
The SI4126-F-GM can support frequency-hopping wireless equipment when its verified tuning and control capabilities cover every required ISM channel. Because the supplied snippets list one synthesizer channel and a 2.3 GHz maximum RF output, the design must ensure that hop rates, channel spacing, and lock timing fit the device. Firmware or external control circuitry must command valid frequencies without disturbing adjacent channels or violating applicable radio regulations.
Industrial Sensor Link
Industrial sensors and remote telemetry links can benefit when they use an ISM-band carrier generated by the SI4126-F-GM. The integrated synthesizer reduces the component count associated with a discrete VCO approach, while the 28-pin exposed-pad package supports compact RF layouts. Engineers must check frequency coverage, tuning accuracy, supply regulation, sensitivity, and conducted or radiated emissions before choosing the device for a particular industrial band or regional allocation.
Portable Wireless Endpoint
A portable wireless endpoint may use the SI4126-F-GM when low standby current and integration are important. The verified data identifies 5 uA standby current, which helps reduce energy use when the radio is inactive, and 25.7 mA typical operating current for initial power budgeting. Actual battery-life calculations should include wake-up, lock, transmit, receive, and power-amplifier states. The exposed-pad layout also requires careful thermal and RF grounding.
RF Test and Measurement Source
The SI4126-F-GM may serve as the RF source in compact test equipment when the desired output lies within its verified 2.3 GHz listed capability. A single synthesizer can support controlled stimulus for receiver-chain or mixer testing, but amplitude accuracy, calibration, frequency resolution, phase noise, and settling time must be checked in the full datasheet. The instrument design should also provide output attenuation, shielding, and reference-clock distribution as required by the test specification.
Engineering reference data for SI4126-F-GM — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product |
|---|---|
| Brand | Skyworks |
| Package | 28-pin VQFN exposed pad, 5 mm x 5 mm |
| Product Type | ISM RF frequency synthesizer |
| Maximum RF Output Frequency | 2.3 GHz |
| Number of Channels | 1 |
| Input Frequency Range | 2 MHz to 50 MHz |
| Typical Supply Current | 25.7 mA |
| Standby Current | 5 uA |
| Integrated Elements | VCO, loop filter, varactors, and resonators |
Design Notes
Implement the exposed pad and ground connections exactly as shown by the manufacturer's land pattern. Place required power and bypass capacitors close to their associated pins and provide a low-impedance return plane for the VCO and PLL circuitry. Because the verified sources confirm an exposed-pad package but do not provide the pad dimensions or pin map, do not infer copper geometry from a generic 28-QFN layout.
Keep the reference oscillator, synthesizer feedback path, loop-filter components, and RF output routing short and isolated from noisy switching nodes. Preserve the manufacturer's component-placement and grounding topology so parasitic inductance does not degrade tuning or loop stability. The exposed pad should be connected as directed by the datasheet rather than treated as an optional thermal feature.
Estimated initial power use is 25.7 mA times the required supply voltage using the verified typical-current figure; this is an engineering estimate, not a guaranteed operating point. Confirm whether a separate power amplifier, regulator, or output driver is needed and size the rail for its peak current. The 5 uA standby value should be checked against the intended power-down architecture and leakage from surrounding circuitry.
Do not use the listed 2 MHz to 50 MHz input range as an RF tuning range or assume that the 2.3 GHz output figure guarantees performance at every frequency. Verify reference amplitude, programming levels, supply voltage, tuning limits, lock behavior, and output power in the complete manufacturer datasheet. Also reconcile the historical Silicon Labs documentation with current Skyworks distributor records before purchasing an unverified substitute.
Compliance Information
The supplied verified sources do not state RoHS, REACH, lead-free, halogen-free, or conflict-mineral status. AEC-Q100 is treated as not applicable because the device is not identified as an automotive-qualified part.
