SI4133-D-GT - 1.8 GHz Dual-Band RF Synthesizer | Skyworks
MPN: SI4133-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 |
SI4133-D-GT Overview
A frequency synthesizer is a phase-locked-loop component that combines a voltage-controlled oscillator with a phase detector, loop filter, dividers, and reference path to generate stable programmable frequencies. In the broader semiconductor hierarchy, the SI4133 is an RF synthesizer, a phase-locked-loop device, a clock-and-timing IC, and an integrated transceiver support component. Its integrated VCO architecture is intended to reduce external passive count and eliminate separate external VCOs and varactor diodes.
The SI4133 includes three VCOs supporting RF1, RF2, and IF synthesis. Verified distributor information identifies it as a frequency-synthesizer IC with one RF1/RF2/IF output function and a 1.8 GHz headline frequency. A separate source excerpt gives a maximum input frequency of 26 MHz, a 2.7 V to 3.6 V supply range, three circuits, low phase noise, programmable power-down, and 1 µA standby current; these values should be confirmed against the manufacturer datasheet before design release.
RF integration simplifies wireless RF front-end design by placing the synthesizer functions on one monolithic device. The internal dividers and phase detectors support programmable dual-band RF generation, while the loop filters regulate feedback around each VCO. Compared with a discrete synthesizer implementation, this integrated approach can reduce board area and external RF components, but loop-filter values, reference quality, output power, spur behavior, and supply decoupling remain critical system-level considerations.
Typical uses include wireless personal communications, dual-band radio equipment, IF synthesis, RF transceiver local-oscillator generation, and other frequency-generation systems operating within the device's specified limits. The TSSOP-24 package supports conventional PCB assembly, but RF trace routing, controlled ground return paths, and compact decoupling layouts remain important because supply and reference disturbances can affect phase noise and spur performance.
The most important design step is to follow the manufacturer reference design for pin termination, ground connection, loop-filter implementation, reference input conditioning, and RF output matching. Do not infer unreported package pin functions from distributor summaries. Verify the complete SI4133 pinout, recommended decoupling, operating temperature, RF output specifications, and register/programming requirements against the manufacturer datasheet before PCB release.
This page combines verified distributor identification, the official manufacturer overview, and clearly marked data gaps. It also distinguishes genuinely supported drop-in evidence from unreleased packaging or terminal-style variants, helping engineers avoid treating a similar RF synthesizer as a PCB-compatible replacement without footprint and function verification.
Drop-in alternatives for SI4133-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 SI4133-D-GT (same form factor and footprint) — differing in Integrated VCO Count, Mounting Type, Package, Product Type, Standby Current.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
SI4133-BT
✅ Drop-In✓ In Stock
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View Datasheet →SI4133-D-GT Specifications
| Product Type | Monolithic dual-band RF frequency synthesizer |
| Maximum Stated Synthesizer Frequency | 1.8 GHz |
| Maximum Input Frequency | 26 MHz |
| Supply Voltage | 2.7 V to 3.6 V |
| Integrated VCO Count | 3 VCOs |
| Synthesizer Outputs | RF1, RF2, and IF |
| Circuit Count | 3 circuits |
| Standby Current | 1 µA |
| Power-Down Modes | Programmable |
| Loop-Filter Integration | Integrated |
| Phase-Detector Integration | Integrated |
| Divider Integration | Reference and VCO dividers integrated |
| External VCO Requirement | None; external VCOs and varactor diodes eliminated |
| Package | 24-pin TSSOP, 0.173 inch by 4.40 mm width |
| Mounting Type | Surface mount |
SI4133-D-GT 24-pin tssop, 0.173 inch by 4.40 mm width Pin Configuration Guide
Pin configuration for SI4133-D-GT (24-pin tssop, 0.173 inch by 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 SI4133-D-GT.
Refer to the datasheet for full pin configuration.
Typical Applications
SI4133-D-GT is suitable for 6 applications: Dual-Band Wireless Communications, RF Transceiver Local Oscillator, IF Signal-Chain Frequency Generation, Wireless Personal Communications, Low-Power RF Test and Measurement, Compact RF Communication Modules.
Dual-Band Wireless Communications
The SI4133-D-GT fits dual-band wireless communications because Skyworks identifies it as a dual-band RF synthesizer with three integrated VCOs and RF1, RF2, and IF outputs. Placing RF1 and RF2 synthesis on one IC can reduce external VCO, varactor, and passive-component count compared with a discrete implementation. The 1.8 GHz maximum stated synthesizer frequency and 2.7 V to 3.6 V supply excerpt should be checked against the band plan and RF power budget. Designers should use the manufacturer reference circuit and validate reference-noise coupling, channel spacing, spur levels, and output matching on the final PCB.
Recommended
RF Transceiver Local Oscillator
SI4133-D-GT is suitable for RF transceiver local-oscillator generation when a design needs programmable RF1 and RF2 outputs from an integrated synthesizer. The three-VCO architecture supports distinct synthesis functions, while the integrated phase detectors, dividers, and loop filters reduce the number of external RF components. The 1.8 GHz headline specification must be reconciled with the actual LO range and harmonic requirements of the selected transceiver. Keep the reference input and RF outputs away from noisy switching nodes, and verify phase noise, spur isolation, output drive, and impedance matching with the manufacturer’s recommended layout.
Recommended
IF Signal-Chain Frequency Generation
The IF output makes SI4133-D-GT applicable to wireless signal chains that require synthesized intermediate-frequency signals alongside RF outputs. Its integrated loop filters, reference and VCO dividers, and phase detectors provide the core functions needed for programmable frequency generation in one monolithic IC. The supplied data lists a 2.7 V to 3.6 V supply range and 26 MHz maximum input frequency, but does not provide IF output power or tuning range. Engineers should confirm those values, then validate IF frequency accuracy, spur performance, and reference phase-noise contribution against the receiver or transmitter requirements.
Recommended
Wireless Personal Communications
Skyworks specifically describes the SI4133-D-GT for price-sensitive, low-power, high-performance personal wireless communications. Its integrated VCOs eliminate external VCOs and varactor diodes, while the integrated loop filters and phase detectors can simplify RF synthesis implementation. This makes the device relevant to compact transceivers and personal wireless equipment where component count and board area matter. The 1 µA standby-current excerpt is useful for power-state planning, but active current and shutdown behavior must be checked in the full datasheet. Confirm the required frequency plan, output levels, locking time, and temperature range before design commitment.
Recommended
Low-Power RF Test and Measurement
SI4133-D-GT can serve as a compact RF frequency source in test and measurement equipment requiring RF1, RF2, or IF synthesis. The integrated VCO and divider structure avoids the discrete component count of a traditional RF synthesizer, helping reduce board area in portable instruments. The device’s 1.8 GHz maximum stated frequency is suitable only where the required output lies within the verified limits, and the 26 MHz maximum input-frequency excerpt may constrain some reference architectures. Engineers should characterize phase noise, close-in spurs, lock time, output power, temperature stability, and RF shielding before using it as a measurement source.
Recommended
Compact RF Communication Modules
The SI4133-D-GT is a candidate for compact RF communication modules where board area and external RF component count are constrained. Its monolithic integration combines three VCOs, loop filters, reference and VCO dividers, and phase detectors in a 24-pin TSSOP package. This can simplify RF synthesis assembly compared with a discrete VCO, varactor, and feedback network. However, a TSSOP package does not remove RF-layout sensitivity: keep the reference route short, provide the manufacturer-recommended supply bypass network, maintain a continuous ground plane, and validate isolation from module power supplies and digital switching nodes.
Recommended
Engineering reference data for SI4133-D-GT — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | SI4133-BT |
|---|---|---|
| Brand | Skyworks Solutions Inc. | Silicon Laboratories / Skyworks-related listing |
| Package | 24-TSSOP, 4.40 mm width | 24-TSSOP, 4.40 mm width |
| Product Function | Dual-band RF and IF frequency synthesizer | Frequency synthesizer IC |
| Pin-to-Pin Compatibility | Reference design basis | Not verified by supplied data |
Key Differentiators
- Three integrated VCOs in one synthesizer IC (vs SI4133-BT)
- Integrated RF1, RF2, and IF synthesis architecture (vs SI4133-BT)
- Low external RF component count (vs SI4133-BT)
Design Notes
Use the manufacturer application circuit and preserve continuous RF and reference return paths. Keep the reference input route away from RF outputs, switching inductors, and high-current supply nodes. The SI4133-D-GT contains three VCOs and phase-sensitive loop functions, so reference-noise coupling can degrade phase noise or spur performance. A compact layout is not automatically a good RF layout; maintain controlled ground continuity and follow the datasheet’s recommended PCB stack-up and via guidance.
Design the supply network around the verified 2.7 V to 3.6 V excerpt, but confirm the definitive limits in the manufacturer datasheet. Place bypass capacitors close to the device power and ground pins and use the manufacturer-recommended values rather than generic bulk-capacitor substitutions. Estimate rail-current dissipation from the actual active current and voltage drop, then verify startup, shutdown, and standby behavior. The 1 µA standby-current figure does not represent active operating current.
Do not treat every Si4133 suffix as a drop-in equivalent merely because related listings use a 24-TSSOP package. Verify pin names, ground positions, RF output functions, reference-input requirements, programming signals, loop-filter implementation, and electrical limits for the exact MPN. Also verify the PCB land pattern and exposed-terminal treatment. A package-width match is not evidence of pin-to-pin compatibility, especially when the available data does not provide a complete manufacturer pin table.
Reference phase noise and power-supply ripple can influence synthesizer phase noise and spurious products. Keep the reference clock source and distribution network isolated from noisy digital and switching circuitry, and follow the manufacturer’s recommended filtering. During prototype validation, measure output power, lock behavior, phase noise, and spurs under the intended reference and supply conditions. Use the verified 1.8 GHz headline value only as a maximum stated synthesizer-frequency indication, not as proof of every output range or mode.
Compliance Information
The supplied search results include a third-party datasheet page with a RoHS field but do not provide a confirmed compliance statement. Compliance status is therefore unknown rather than assumed.
