ADF4355-3 Analog Devices Integrated Circuit (Quad Flat No-Lead) In Stock
Analog Devices ADF4355-3 is a wideband microwave PLL frequency synthesizer with integrated VCO covering 3.3 GHz to 6.6 GHz output frequency range, featuring fractional-N and integer-N modes with SPI control in a 40-pin QFN package. Ideal for local oscillator generation in microwave, radar, and wireless infrastructure equipment.
- Manufacturer
- Analog Devices
- Package
- Quad Flat No-Lead
- Pin Count
- 33
- Lifecycle
- ACTIVE
- Datasheet
- ADF4355-3 Datasheet PDF
- Category
- Integrated Circuit
- RoHS
- Compliant
- Lead Time
- 3–7 business days
- Shipping
- DHL Express · Worldwide
Key Features
- Integrated VCO with output frequency range of 3.3 GHz to 6.6 GHz enabling wideband local oscillator synthesis without external VCO
- Fractional-N and integer-N synthesizer modes with 10-bit modulus for fine frequency resolution down to sub-Hz steps via SPI programming
- Low phase noise performance suitable for demanding radar and point-to-point microwave backhaul carrier applications
- Compact 40-pin QFN package integrating PLL, VCO, and output dividers for reduced BOM in high-frequency RF front-end designs
Applications
The ADF4355-3 microwave PLL synthesizer is used as a local oscillator source in point-to-point microwave backhaul radios and millimeter-wave test equipment operating in the 3 GHz to 7 GHz frequency bands. Its integrated VCO and wide tuning range allow frequency agility across multiple communication channels in 5G NR sub-6 GHz radio units, direct-conversion receivers, and FMCW radar waveform generators. Defense electronic warfare systems and satellite communication ground terminals also employ this device for its low-noise synthesis capability and SPI-programmable frequency step resolution.
Compliance & Regulatory
| RoHS Status | Compliant |
| Lead-Free | Yes (Pb-Free) |
Alternate & Equivalent Parts
Compatible alternatives and drop-in replacements for ADF4355-3:
Frequently Asked Questions
What output frequency range does the ADF4355-3 cover and how is the frequency programmed?
The ADF4355-3 VCO directly covers an output frequency range of 3.3 GHz to 6.6 GHz, and internal divide-by-N output dividers extend the usable output range down to lower sub-GHz frequencies. Frequency programming is performed via a 3-wire SPI interface by writing to the on-chip integer and fractional registers, allowing frequency step resolution in the sub-Hz range at a 100 MHz reference input with a 10-bit fractional modulus.
What reference clock frequency is required to operate the ADF4355-3 and what is the minimum phase detector frequency?
The ADF4355-3 accepts a reference input frequency from 10 MHz to 600 MHz. The phase detector frequency, which equals the reference frequency divided by the R counter, can range from a minimum of approximately 125 kHz up to 100 MHz for integer-N operation. Higher phase detector frequencies such as 50 MHz to 100 MHz improve phase noise performance by narrowing the PLL loop bandwidth relative to the VCO noise floor.
For a 5G sub-6 GHz radio design, why would an engineer select the ADF4355-3 over a fixed-frequency crystal oscillator?
A 5G NR radio must hop across multiple carrier frequencies spanning 3.3 GHz to 4.2 GHz (n77/n78 bands) and up to 6 GHz (n41 and n258 candidate bands), which fixed crystal oscillators cannot cover. The ADF4355-3 synthesizes any frequency in the 3.3 GHz to 6.6 GHz range with sub-kHz step resolution, enabling software-defined frequency agility within 50 µs lock time, which is essential for fast channel switching in TDD-NR frame structures.
How does the ADF4355-3 QFN package affect PCB thermal management in a high-frequency RF module?
The ADF4355-3 40-pin QFN package includes an exposed thermal pad on its bottom side, which must be soldered to a PCB copper plane for effective heat dissipation. At full VCO operation near 6.6 GHz with a 3.3V supply, total supply current is typically 100 mA to 150 mA, resulting in 330 mW to 495 mW of power dissipation. The thermal pad connected to at least a 25 mm² ground copper area keeps junction temperature below 85°C in a 25°C ambient environment without a heatsink.
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About Analog Devices
Analog Devices (ADI) is a global leader in high-performance analog, mixed-signal, and digital signal processing integrated circuits used in virtually all types of electronic equipment.
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