SI4122-BT - 1.5 GHz Dual-Band RF Synthesizer | Silicon Labs
MPN: SI4122-BT ✗ End of Life| Qty | Unit Price | Extended |
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| 1 | $0 | $0.00 |
| 10 | $0 | $0.00 |
| 100 | $0 | $0.00 |
| 500 | $0 | $0.00 |
| 1,000 | $0 | $0.00 |
SI4122-BT Overview
A frequency synthesizer is a clock-and-timing IC that generates a stable output frequency from a reference signal. This synthesizer supports wireless-communication RF signal chains, where programmable frequency generation is used for local oscillators, transceivers, and related RF functions. Its 1.5 GHz headline specification identifies the supported synthesis range in the distributor data, while the dual-band architecture supports wireless RF signal-generation requirements.
The SI4122-BT is identified as a frequency-synthesizer IC with a 1:2 input-to-output ratio in the available distributor records. The available data also reports 18 mA typical supply current, 1 µA standby current, 3.6 V operation, and integrated VCO, loop-filter, varactor, and resonator functions. These features are useful where designers want to minimize external RF support components and simplify the synthesizer implementation.
The 24-TSSOP package has a 0.173 inch, or 4.40 mm, width according to the DigiKey result. It is a surface-mount package, and the available distributor data identifies a 24-pin TSSOP with SMD/SMT mounting. Exact pin names, operating-temperature limits, phase-noise figures, frequency ranges by band, and full electrical limits were not supplied in the verified data and are therefore not inferred here.
Typical applications include wireless-communication transmitters and receivers, RF transceiver local-oscillator paths, dual-band RF signal generation, and embedded RF systems requiring a programmable synthesizer. Designers should confirm the complete pinout, reference requirements, loop-filter configuration, and band-specific operating limits against the manufacturer datasheet before layout or firmware release.
For implementation, preserve the supplied 24-pin TSSOP footprint and validate the reference and RF routing according to the manufacturer’s layout guidance. The integrated resonator and VCO functions can reduce external component count, but RF layout, grounding, decoupling, and keep-out requirements remain critical.
This page consolidates verified distributor specifications, sourcing links, packaging information, and design considerations while clearly identifying parameters that still require datasheet confirmation.
Drop-in alternatives for SI4122-BT — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with SI4122-BT (same form factor and footprint) — differing in Mounting Type, Package, Standby Current, Typical Supply Current, External Components Required.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
No drop-in alternatives available for this product.
Request AlternativesSI4122-BT Specifications
| Product Type | Frequency synthesizer IC |
| Frequency | 1.5 GHz |
| Supply Voltage Range | 2.7 V to 3.6 V |
| Typical Supply Current | 18 mA |
| Standby Current | 1 µA |
| Architecture | Dual-band RF synthesizer |
| Integrated Blocks | Integrated VCOs, loop filters, varactors, and resonators |
| External Components Required | 2 minimum |
| Input-to-Output Ratio | 1:2 |
| Operating Mode | 3.6 V operation |
| Package | 24-pin TSSOP |
| Package Width | 0.173 in (4.40 mm) |
| Mounting Type | SMD/SMT |
| Category | Clock/Timing - Clock Generators, PLLs, Frequency Synthesizers |
| Manufacturer | Silicon Labs |
| MSL Level | Level 3, 168 hours |
| HTSUS Code | 8542.39.0001 |
SI4122-BT 0.173 in (4.40 mm) Pin Configuration Guide
Pin configuration for SI4122-BT (0.173 in (4.40 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 SI4122-BT.
Refer to the datasheet for full pin configuration.
Typical Applications
SI4122-BT is suitable for 6 applications: Dual-Band Wireless RF Signal Generation, RF Transceiver Local Oscillator, Wireless Communications Transmitter, RF Receiver Frequency Generation, Programmable RF Test and Measurement Equipment, Embedded Wireless Sensor and IoT Module.
Dual-Band Wireless RF Signal Generation
The SI4122-BT fits dual-band wireless RF signal-generation paths because the verified data identifies a dual-band RF synthesizer with integrated VCOs, loop filters, varactors, and resonators. The 1.5 GHz frequency specification provides a defined RF operating point for wireless designs, while the 2.7 V to 3.6 V supply range suits low-voltage systems. Place the synthesizer according to the manufacturer layout guidance, provide controlled reference routing, and verify the selected RF band, output impedance, and loop-filter configuration before release.
Recommended
RF Transceiver Local Oscillator
The SI4122-BT can support RF transceiver local-oscillator requirements when the selected synthesis band matches the transceiver architecture. Its integrated synthesizer blocks reduce the number of external RF-support components reported by the available listing, while the 18 mA typical supply current provides a concrete power-budget reference for portable equipment. Validate reference phase noise, spur requirements, output power, and isolation because those parameters were not included in the verified data and must come from the manufacturer documentation.
Recommended
Wireless Communications Transmitter
The SI4122-BT is described as a dual-band RF synthesizer for wireless communications, making it relevant to programmable transmitter chains that require accurate frequency generation. The integrated VCO, loop filter, varactor, and resonator functions can simplify RF implementation compared with a discrete synthesizer approach. Designers should still budget for reference routing, supply decoupling, impedance matching, shielding, and output-buffer requirements, and should confirm the exact band-plan compatibility with the transmitter requirements.
Recommended
RF Receiver Frequency Generation
The SI4122-BT may be used in receiver architectures that need programmable RF frequency generation for tuning or local-oscillator functions. Its 1.5 GHz listed frequency and dual-band description provide the starting point for matching the receiver’s RF plan. The available data does not include phase-noise, tuning-step, spur, or sensitivity figures, so the receiver’s adjacent-channel and blocking requirements must be verified before selecting the device.
Recommended
Programmable RF Test and Measurement Equipment
The SI4122-BT can be considered for programmable RF test equipment when the instrument needs a compact, integrated frequency-synthesizer function. Its 2.7 V to 3.6 V operating range and 18 mA typical supply current are useful constraints for compact instrument designs. For measurement accuracy, validate output level, frequency accuracy, tuning resolution, phase noise, spurious response, and calibration requirements; these specifications were not available in the verified search data.
Recommended
Embedded Wireless Sensor and IoT Module
The SI4122-BT may suit embedded wireless modules that require programmable RF generation within a compact 24-pin TSSOP footprint. The listed package width of 4.40 mm and integrated synthesizer functions can help reduce board-level RF component count, while the 1 µA standby current is relevant to low-power designs. Confirm whether the standby state preserves required state, how firmware controls power-down, and whether the RF performance meets the module’s emission and reception requirements.
Recommended
Recommended Products Summary
Engineering reference data for SI4122-BT — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | SI4122-D-GT | SI4112-BT | SI4133-BT | SI4136-BT | SI4122-D-GTR |
|---|---|---|---|---|---|---|
| Package | 24-pin TSSOP | TSSOP-24 | TSSOP-24 | TSSOP-24 | TSSOP-24 | TSSOP-24 |
| Brand | Silicon Labs | Skyworks Solutions | Skyworks Solutions | Silicon Labs | Silicon Labs | Skyworks Solutions |
| Product Type | Frequency synthesizer IC | RF synthesizer | RF synthesizer | RF synthesizer | RF synthesizer | RF synthesizer |
| Mounting Style | SMD/SMT | SMD/SMT | SMD/SMT | SMD/SMT | SMD/SMT | SMD/SMT |
Key Differentiators
- Integrated dual-band RF synthesis architecture (vs SI4122-D-GT)
- Low reported standby current (vs SI4112-BT)
- Integrated RF support blocks (vs SI4133-BT)
- Documented 1:2 input-to-output ratio (vs SI4136-BT)
Design Notes
Treat the RF synthesizer as a high-frequency RF layout block rather than a general-purpose digital IC. Keep the reference, VCO, resonator, and output paths short and controlled, provide a continuous ground reference, and follow the manufacturer’s recommended decoupling and keep-out geometry. The verified data does not include a complete reference PCB layout, so these details must be taken from the current datasheet.
Budget the supply rail around the reported 2.7 V to 3.6 V operating range and 18 mA typical supply current. Add local high-frequency decoupling close to the device and verify startup, standby, and power-down behavior in firmware. Estimated: using the reported 18 mA typical current at 3.3 V gives a nominal 59.4 mW operating power, before regulator losses, I/O loading, and frequency-dependent effects.
Do not substitute a generic TSSOP-24 frequency synthesizer solely because the package matches. Confirm pin assignment, reference-input requirements, frequency bands, RF output topology, loop-filter implementation, supply sequencing, and calibration requirements. The supplied cross-reference data identifies related TSSOP-24 parts but does not establish manufacturer-confirmed pin-to-pin equivalence.
RF synthesizer outputs can create unwanted harmonics and conducted or radiated emissions, especially when the reference and RF paths are poorly isolated. Use controlled return paths, maintain separation between sensitive receiver nodes and synthesizer RF routing, and validate the assembled board with the intended reference clock and antenna or load. The available data does not provide conducted-emission, spur, or phase-noise limits.
Compliance Information
The verified data identifies MSL Level 3 with a 168-hour floor life and HTSUS code 8542.39.0001. RoHS, REACH, lead-free, halogen-free, and conflict-minerals statuses were not supplied and remain unknown.
