SI4123-D-GT - 1.8 GHz Dual-Band RF Synthesizer | Skyworks Solutions
MPN: SI4123-D-GT ✗ 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 |
SI4123-D-GT Overview
An RF frequency synthesizer is a phase-locked-loop device that generates stable, programmable RF or IF carrier signals for wireless transmitters, receivers, and related communication equipment. The SI4123-D-GT belongs to the RF synthesizer family and integrates two VCOs, allowing dual-band operation without requiring external VCOs or varactor diodes. Its intended role is local oscillator or carrier generation in systems requiring accurate frequency selection and low-noise RF performance.
Verified product information lists a 900 MHz to 1.8 GHz primary frequency range and a 750 MHz to 1.5 GHz secondary range, an output-power range of -14 dBm to +1 dBm, and harmonic levels from -26 dBc to -20 dBc. The specified supply-voltage range is 2.7 V to 3.6 V, with current consumption from 18 mA to 27 mA. These values position the device for compact, low-power wireless products operating near direct-conversion or low-IF architectures.
The integrated VCO approach reduces external passive-component count compared with discrete oscillator implementations. It can also simplify RF board layout by eliminating external varactor tuning networks, although loop-filter selection, reference routing, supply decoupling, output matching, and phase-noise requirements remain essential to achieve predictable RF performance.
Typical applications include wireless personal communications, dual-band cellular equipment, RF transceivers, IF-generating receiver paths, and compact RF communication modules. The device is most appropriate when the system operates from a 2.7 V to 3.6 V supply and needs programmable synthesis across either of the verified frequency bands.
Designers should verify the manufacturer’s reference circuit and pin-specific programming requirements before layout. Keep the reference, synthesizer, and RF output paths short, provide the required bypass capacitors at the supply pins, and preserve controlled impedance routing for high-frequency outputs. Because exact pin names, register behavior, loop-filter values, and absolute phase-noise data were not supplied in the verified data, those details must be confirmed from the manufacturer datasheet.
This page consolidates the verified manufacturer description, distributor package information, frequency, power, supply, and current data into an application-oriented engineering summary. It also distinguishes true drop-in alternatives from functional RF substitutes, preventing redesign-level parts from being presented as pin-compatible replacements.
Drop-in alternatives for SI4123-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 SI4123-D-GT (same form factor and footprint) — differing in Package, RoHS Status, Device Type, Input-to-Output Ratio, Integrated VCOs.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
No drop-in alternatives available for this product.
Request AlternativesSI4123-D-GT Specifications
| Device Type | Dual-band RF frequency synthesizer with integrated VCOs |
| Primary Frequency Range | 900 MHz to 1800 MHz |
| Secondary Frequency Range | 750 MHz to 1500 MHz |
| Maximum Stated Frequency | 1.8 GHz |
| Output Power Range | -14 dBm to +1 dBm |
| Harmonic Level Range | -26 dBc to -20 dBc |
| Supply Voltage Range | 2.7 V to 3.6 V |
| Supply Current Range | 18 mA to 27 mA |
| Integrated VCOs | 2 integrated VCOs |
| Package | 24-pin TSSOP, 0.173 inch width, 4.40 mm width |
| Mounting Type | Surface mount |
| Product Category | Phase-locked loop / RF synthesizer |
| Application Domain | Wireless personal communications |
| RoHS Status | RoHS indicated for SI4123-D-GT in verified comparison data |
SI4123-D-GT 24-pin tssop, 0.173 inch width, 4.40 mm width Pin Configuration Guide
Pin configuration for SI4123-D-GT (24-pin tssop, 0.173 inch width, 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 SI4123-D-GT.
Refer to the datasheet for full pin configuration.
Typical Applications
SI4123-D-GT is suitable for 6 applications: Dual-Band Wireless Transceiver, Cellular RF Signal Generation, Low-IF Receiver, Compact RF Communication Module, Wireless Personal Communications, RF Test and Measurement Front End.
Dual-Band Wireless Transceiver
The SI4123-D-GT is suitable for dual-band wireless transceiver platforms that need programmable RF synthesis in a compact 2.7 V to 3.6 V design. Its integrated VCOs eliminate external VCOs and varactor diodes, reducing the external component count described by Skyworks Solutions. The verified 900 MHz to 1800 MHz and 750 MHz to 1500 MHz ranges make it relevant for systems supporting two RF bands. The designer must still set the loop-filter components and confirm phase noise, reference requirements, and output power for each channel.
Recommended
Cellular RF Signal Generation
The SI4123-D-GT can provide programmable frequency synthesis for RF sections of compact cellular and personal-wireless equipment. Its dual-band capability supports product variants that must cover the verified 900 MHz to 1800 MHz range and the 750 MHz to 1500 MHz range. The 18 mA to 27 mA operating-current range helps power-conscious designers, while the 2.7 V to 3.6 V supply range simplifies integration with low-voltage RF systems. Exact channel plans, modulation requirements, and regulatory limits must be validated separately.
Recommended
Low-IF Receiver
In a low-IF receiver, the SI4123-D-GT can generate a controlled local oscillator or IF-related carrier for signal conversion. The integrated dual-VCO architecture helps avoid discrete tuning components and can reduce board-level part count. The verified output-power range of -14 dBm to +1 dBm provides a useful starting point for RF path planning, although the actual usable level depends on configuration and matching. Designers should use controlled-impedance routing and keep the reference and sensitive RF nodes away from noisy digital return paths.
Recommended
Compact RF Communication Module
The SI4123-D-GT is appropriate for compact RF communication modules where a dedicated synthesizer is needed without an external VCO assembly. Its integrated VCOs support a lower component count, while the verified TSSOP-24 surface-mount package supports dense PCB construction. The module designer must plan local bypass capacitors, a stable reference source, an approved loop filter, and RF output matching. The 1.8 GHz maximum stated frequency should be checked against the module’s antenna, matching network, enclosure, and regulatory requirements.
Recommended
Wireless Personal Communications
The SI4123-D-GT is explicitly targeted by Skyworks Solutions at wireless personal communications, combining dual-band synthesis with integrated VCOs. It is useful where product variants need different RF ranges without changing the external oscillator architecture. The verified 2.7 V to 3.6 V supply range and 18 mA to 27 mA current range support low-power integration, while the output range of -14 dBm to +1 dBm informs the RF budget. Exact receiver sensitivity and transmitter compliance remain dependent on the complete signal chain, not this IC alone.
Recommended
RF Test and Measurement Front End
The SI4123-D-GT can serve as a programmable RF signal source for selected test and measurement front ends when its verified frequency, supply, and output specifications fit the instrument architecture. Its dual-band coverage allows the same synthesizer platform to address two instrument bands, and the integrated VCOs reduce the complexity of maintaining multiple external oscillators. For measurement-grade performance, the engineer must verify phase noise, tuning accuracy, reference stability, calibration method, and output accuracy from the complete datasheet rather than infer them from maximum frequency alone.
Recommended
Recommended Products Summary
Engineering reference data for SI4123-D-GT — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | SI4113-D-GT |
|---|---|---|
| Package | 24-pin TSSOP, 0.173 inch width, 4.40 mm width | TSSOP-24 |
| Brand | Skyworks Solutions | Skyworks Solutions |
Key Differentiators
- Integrated dual-VCO architecture (vs Discrete VCO implementation)
- Dual-band frequency coverage (vs Single-band RF synthesizer)
- Low-voltage RF integration (vs Higher-voltage RF synthesizer)
- Wireless personal-communications positioning (vs General-purpose clock generator)
Design Notes
Use the manufacturer’s reference layout as the starting point for the 24-pin TSSOP footprint. Keep the reference path, VCO-related connections, supply pins, and RF outputs short, and preserve controlled impedance for RF routes. Maintain a continuous ground reference beneath and around the device where the package and board stackup allow it; inadequate return paths can degrade phase noise and RF isolation even when the nominal component values are correct.
The SI4123-D-GT is verified for a 2.7 V to 3.6 V supply range and 18 mA to 27 mA current range. Place the required bypass capacitors close to the supply pins, verify their voltage and temperature ratings, and keep switching-regulator noise away from the reference and RF paths. Treat 27 mA as a verified upper listed current rather than a complete worst-case design limit, because transient, temperature, and configuration data were not provided.
The integrated VCO architecture reduces external tuning components but does not eliminate RF layout sensitivity. Route the outputs through the intended matching network, minimize discontinuities, and keep the loop-filter and reference components close to their associated pins according to the manufacturer circuit. Validate phase noise, spur levels, output power, and tuning accuracy with the final board and enclosure rather than relying only on nominal synthesizer specifications.
Compliance Information
RoHS status is indicated by the verified SI4123-D-GT comparison listing. No verified REACH, AEC-Q100, lead-free, halogen-free, or conflict-minerals declaration was supplied.
