LTC6948IUFD-2

Clock Generators, PLLs, Frequency Synthesizers Overview

The LTC6948IUFD-2 is a fractional-N phase-locked loop synthesizer with an integrated voltage-controlled oscillator (VCO) from Analog Devices. It operates within a VCO frequency range of 3.08 GHz to 4.91 GHz. The device features a 4th-order delta-sigma modulator for low spurious performance and a programmable output divider ranging from 1 to 6. Key electrical specifications include a reference input frequency up to 425 MHz, a charge pump current range of 1 mA to 11.2 mA, and normalized in-band phase noise floors of –225 dBc/Hz (fractional) and –274 dBc/Hz (1/f). It is housed in a 28-lead 4mm x 5mm QFN package.

Clock Generators, PLLs, Frequency Synthesizers Feature Summary

• Integrated VCO with a frequency range of 3.08 GHz to 4.91 GHz
• Advanced 4th-order delta-sigma modulator eliminates discrete spurs
• Programmable output divider (O_DIV) from 1 to 6 extends frequency coverage
• Normalized in-band phase noise floor of –225 dBc/Hz

Clock Generators, PLLs, Frequency Synthesizers Applications

• Wireless basestations (LTE, WiMAX, W-CDMA, PCS)
• Microwave data links
• Military and secure radio systems
• Test and measurement equipment

Clock Generators, PLLs, Frequency Synthesizers Procurement Notes

Verify the specific ordering suffix against manufacturer documentation. The #PBF suffix indicates lead-free finish and tube packaging, while #TRPBF indicates tape and reel packaging. Confirm that the IUFD suffix corresponds to the industrial temperature range of –40°C to 105°C. Ensure the component matches the 28-lead QFN physical dimensions.

Clock Generators, PLLs, Frequency Synthesizers Selection Notes

Select the LTC6948IUFD-2 variant when the required VCO frequency falls between 3.08 GHz and 4.91 GHz. Other variants cover different ranges: LTC6948-1 (2.24–3.74 GHz), LTC6948-3 (3.84–5.79 GHz), and LTC6948-4 (4.20–6.39 GHz). Utilize the output divider settings to extend the usable output frequency range beyond the base VCO limits.

Clock Generators, PLLs, Frequency Synthesizers Part Context

The LTC6948 series comprises four distinct models differentiated by their internal VCO frequency ranges. The IUFD-2 specifically targets the 3.08 GHz to 4.91 GHz band. All models share identical architecture, including the integrated VCO, charge pump, and digital control interface, differing only in the tuned frequency characteristics of the on-chip oscillator.

Clock Generators, PLLs, Frequency Synthesizers Replacement Considerations

Publicly confirmed substitute part numbers are not available in the provided datasheet or local source material.