SI4122-D-GT - Dual-Band RF Synthesizer | Silicon Labs
MPN: SI4122-D-GT ✗ End of LifeSI4122-D-GT Overview
An RF synthesizer is a frequency-generation IC that combines a phase-locked loop, frequency dividers, and one or more VCOs to produce coherent high-frequency signals. In the broader electronics hierarchy, it belongs to clock and timing ICs, frequency synthesizers, and phase-locked-loop devices. Its integrated VCOs reduce the need for external oscillators, varactor diodes, and associated passive networks in cost-sensitive wireless transmitters and receivers.
Key operating characteristics include an output-power range of -14 dBm to 1 dBm, harmonic content from -26 dBc to -20 dBc, and supply-current consumption between 18 mA and 27 mA. The 1.5 GHz device designation and dual-band coverage support RF communication architectures operating near the upper GSM, DCS1800, and PCS1900 frequency regions. The 24-pin TSSOP body is approximately 4.40 mm wide according to the distributor data.
The SI4122-D-GT uses phase-locked-loop signal generation to establish the required output frequency and phase relationship. Its RF2/IF output arrangement is intended for wireless communication systems requiring a local oscillator or intermediate-frequency signal. Exact phase-noise, reference-input sensitivity, tuning-step, lock-time, and temperature-coefficient values are not present in the supplied verified results and must be checked against the manufacturer datasheet before final design release.
Typical applications include GSM and DCS-style cellular equipment, dual-band wireless transceivers, RF up-converter and down-converter local-oscillator paths, intermediate-frequency generation, and cost-sensitive industrial RF modules. The integrated-VCO architecture can shorten RF design cycles while reducing external component count and improving integration against environmental interference.
When laying out a replacement board, preserve the 24-pin TSSOP footprint, verify every exposed and supply connection against the original pinout, and place support components according to the manufacturer reference circuit. The 2.7 V to 3.6 V operating range leaves little margin for supply excursions, so regulation, bypass placement, grounding, and VCO loop stability require careful review.
This product record consolidates verified distributor availability, frequency-band data, package information, and same-package cross-reference candidates with practical selection guidance. It highlights verified differences among related Silicon Labs parts so engineers can distinguish true footprint matches from devices that merely share the same package family.
Drop-in alternatives for SI4122-D-GT — 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-D-GT (same form factor and footprint) — differing in Package, Architecture, Manufacturer, Product Type, Mounting Type.
SI4112-BT
✅ Drop-InContact for price
View Datasheet →SI4113-D-GTR
✅ Drop-InContact for price
View Datasheet →SI4122-BT
✅ Drop-InContact for price
View Datasheet →SI4123-D-GTR
✅ Drop-InContact for price
View Datasheet →SI4136-BT
✅ Drop-InContact for price
View Datasheet →SI4122-D-GT Specifications
| Product Type | Dual-band RF synthesizer with integrated VCOs |
| Manufacturer | Silicon Labs / Skyworks Solutions, Inc. |
| Lower RF Frequency Range | 750 MHz to 1500 MHz |
| Upper RF Frequency Range | 900 MHz to 1800 MHz |
| Reference Input Frequency Range | 2 MHz to 26 MHz |
| Supply Voltage Range | 2.7 V to 3.6 V |
| Supply Current | 18 mA to 27 mA |
| Output Configuration | RF2/IF output |
| Output Power | -14 dBm to 1 dBm |
| Harmonic Content | -26 dBc to -20 dBc |
| Device Frequency | 1.5 GHz |
| Architecture | Phase-locked loop with integrated VCOs |
| Package | 24-pin TSSOP, 4.40 mm width |
| Mounting Type | Surface mount |
| Application | Wireless communications |
SI4122-D-GT 24-pin tssop, 4.40 mm width Pin Configuration Guide
Pin configuration for SI4122-D-GT (24-pin tssop, 4.40 mm width 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-D-GT.
Refer to the datasheet for full pin configuration.
Typical Applications
SI4122-D-GT is suitable for 6 applications: Dual-Band Cellular RF Transceiver, RF Up-Converter Local-Oscillator Path, Intermediate-Frequency Signal Generator, Cost-Sensitive Wireless Remote Control, Industrial RF Control Module, Instrumentation RF Signal Source.
Dual-Band Cellular RF Transceiver
The SI4122-D-GT fits a dual-band cellular signal source because its verified RF coverage spans 750 to 1500 MHz and 900 to 1800 MHz. The device can generate a local or intermediate-frequency signal from a 2 MHz to 26 MHz reference while drawing 18 mA to 27 mA from a 2.7 V to 3.6 V supply. Its integrated VCO architecture reduces the external oscillator and varactor network required by a discrete implementation. The principal design qualification is phase noise: the supplied results do not quantify in-band phase noise or spur performance, so both must be checked against the cellular transmitter and receiver masks before production use.
Recommended
RF Up-Converter Local-Oscillator Path
SI4122-D-GT can supply the local-oscillator signal required by a dual-band RF up-converter, with its RF2/IF output positioned as the intended synthesized output. The verified operating bands provide coverage around 750 to 1800 MHz, while the reference input accepts 2 MHz to 26 MHz. Its output-power range of -14 dBm to 1 dBm should be included in the mixer drive budget and downstream gain-control analysis. Because coupling into adjacent channels depends on phase noise and reference purity, the board should use a clean reference source, controlled return paths, and manufacturer-recommended loop-filter components.
Recommended
Intermediate-Frequency Signal Generator
The SI4122-D-GT is suitable for generating a coherent IF-related signal in a wireless receiver or transmitter because the verified output configuration includes an IF output. Its two operating bands, 750 to 1500 MHz and 900 to 1800 MHz, allow a single RF synthesis device to support two planbands, while the 24-pin TSSOP package supports compact surface-mount construction. The design must reconcile the -14 dBm to 1 dBm available output power with the receiver gain cascade and mixer requirements. Exact IF tuning resolution, lock time, and reference sensitivity are not supplied and require validation from the manufacturer datasheet.
Recommended
Cost-Sensitive Wireless Remote Control
A compact wireless remote or sensor transmitter can benefit from the SI4122-D-GT because integrated VCOs reduce the number of external high-frequency components in a cost-sensitive RF design. Its 24-pin TSSOP package, 2.7 V to 3.6 V supply range, and 18 mA to 27 mA current span support low-power portable equipment. The two available band ranges must align with the permitted transmit channel and regional allocation, while the -14 dBm to 1 dBm output range must be considered in the antenna and power-amplifier design. Harmonics of -26 dBc to -20 dBc are verified, but the complete emission mask still depends on filtering and PCB parasitics.
Recommended
Industrial RF Control Module
The SI4122-D-GT can serve as the frequency source in an industrial RF control or telemetry module requiring selectable synthesis across the 750 to 1800 MHz region. Its dual-band coverage reduces the need for multiple synthesizer devices, and the integrated-VCO implementation is intended to lower external passive-component count. The 2.7 V to 3.6 V supply requirement calls for a low-noise regulator and local bypass capacitors close to the device. Industrial suitability cannot be confirmed from the supplied results because operating-temperature limits, phase-noise limits, qualification status, and lifecycle status beyond the obsolete indication are not available.
Recommended
Instrumentation RF Signal Source
The SI4122-D-GT may be used in compact RF test and measurement equipment when the required test signal falls within 750 to 1500 MHz or 900 to 1800 MHz and the source can accept a 2 MHz to 26 MHz reference. Its RF2/IF architecture supports coherent generation for receiver characterization, while the documented -14 dBm to 1 dBm power range can serve as the starting point for an adjustable output chain. Measurement accuracy requires attention to reference phase noise, tuning granularity, lock stability, and output-level calibration, none of which are quantified in the supplied search snippets. The obsolete lifecycle indication also makes new instrumentation designs particularly dependent on availability review.
Recommended
Recommended Products Summary
Engineering reference data for SI4122-D-GT — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | SI4112-BT | SI4113-D-GTR | SI4122-BT | SI4123-D-GTR | SI4136-BT |
|---|---|---|---|---|---|---|
| Brand | Silicon Labs / Skyworks Solutions, Inc. | Silicon Labs / Skyworks Solutions, Inc. | Silicon Labs / Skyworks Solutions, Inc. | Silicon Labs / Skyworks Solutions, Inc. | Silicon Labs / Skyworks Solutions, Inc. | Silicon Labs / Skyworks Solutions, Inc. |
| Package | 24-pin TSSOP, 4.40 mm width | 24-pin TSSOP - same | 24-pin TSSOP - same | 24-pin TSSOP - same | 24-pin TSSOP - same | 24-pin TSSOP - same |
| Product Type | Dual-band RF synthesizer with integrated VCOs | RF frequency synthesizer | RF synthesizer with RF1/RF2 output | 1.5 GHz frequency synthesizer | RF synthesizer with RF1/IF output | Clock generator |
Key Differentiators
- Verified dual-band coverage in one RF synthesizer (vs SI4136-BT)
- Target-specific RF2/IF output arrangement (vs SI4113-D-GTR)
- Higher verified maximum reference-input frequency (vs SI4113-D-GTR)
- Integrated-VCO dual-band RF function (vs SI4123-D-GTR)
Design Notes
Use the manufacturer's 24-pin TSSOP land pattern and preserve the documented pin-1 orientation. Place input, output, and supply decoupling components directly beside their associated pins, with the shortest possible ground-return path. RF output routing should avoid parallel runs with sensitive mixer or receiver traces. Because the supplied data confirms a 4.40 mm-wide TSSOP but does not provide a verified pin table or PCB artwork, the package drawing must be cross-checked against the exact D-GT datasheet before fabrication.
The SI4122-D-GT operates from 2.7 V to 3.6 V and consumes 18 mA to 27 mA, so the regulator must remain inside this narrow range under every RF operating condition. Avoid allowing supply ripple or transient overshoot to approach the stated limits. Use low-inductance bypass connections and a quiet reference supply because changes in reference amplitude and supply noise can affect PLL behavior. Exact recommended capacitor values, supply sequencing requirements, and decoupling details require confirmation from the manufacturer application circuit.
Treat the reference input, loop-filter network, VCO-control path, and RF2/IF output as a compact RF subsystem. Keep loop-filter components close to their associated pins, avoid routing the sensitive output over split ground planes, and use a continuous ground reference beneath the device where the package permits. External passive-component placement can materially affect loop stability and RF coupling. Do not substitute arbitrary values for the manufacturer's loop filter or matching network because the supplied results provide no verified component list or tuning procedure.
Do not treat equal package dimensions as proof that a related synthesizer is a drop-in replacement. SI4113-D-GTR and SI4123-D-GTR use different verified output assignments, while SI4136-BT is described as a clock generator. Before substitution, compare all 24 pins, reference frequency, tuning interface, RF output level, supply current, phase noise, and absolute maximum ratings. For a released PCB, retain an original-source SI4122-D-GT where possible; otherwise complete a controlled engineering change with schematic, layout, and RF-performance qualification.
Compliance Information
The supplied verified results do not state RoHS, REACH, AEC-Q100, lead-free, halogen-free, or conflict-minerals status. AEC-Q100 is not applicable to this RF synthesizer based on the provided product description, but the remaining environmental and material-compliance fields remain unknown.
