LTC6948IUFD-4

Clock Generators, PLLs, Frequency Synthesizers Overview

The LTC6948IUFD-4 is a fractional-N phase-locked loop synthesizer with an integrated voltage-controlled oscillator (VCO). It operates within a VCO frequency range of 4.20 GHz to 6.39 GHz and supports output frequencies from 0.700 GHz to 6.390 GHz via a programmable divider (1–6). Key electrical parameters include a reference input frequency up to 425 MHz, a charge pump current range of 1 mA to 11.2 mA, and supply voltages of 3.3 V for digital/RF sections and 5 V for the VCO and charge pump. The device utilizes a 4th-order delta-sigma modulator to minimize spurious tones.

Clock Generators, PLLs, Frequency Synthesizers Feature Summary

• Integrated VCO with a frequency range of 4.20 GHz to 6.39 GHz
• Ultralow noise performance with –226 dBc/Hz normalized in-band phase noise floor
• Advanced 4th-order delta-sigma modulator eliminates fractional spurs
• Programmable output divider with integer settings from 1 to 6

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 suffix (#PBF or #TRPBF) against the required packaging format (tube or tape and reel). Confirm that the design accommodates the distinct power supply requirements: 3.3 V for VREF+, VD+, and VRF+, and 5 V for VCP+ and VVCO+. Ensure the PCB layout supports the thermal dissipation of the exposed pad on the QFN package.

Clock Generators, PLLs, Frequency Synthesizers Selection Notes

Select the LTC6948IUFD-4 variant specifically when the application requires a VCO frequency range between 4.20 GHz and 6.39 GHz. Other variants in the family cover lower frequency bands (e.g., LTC6948-1 covers 2.24–3.74 GHz). The choice of output divider setting directly impacts the final output frequency range and phase noise characteristics.

Clock Generators, PLLs, Frequency Synthesizers Part Context

The LTC6948 series comprises four variants differentiated by their internal VCO frequency ranges. The IUFD-4 model targets the highest frequency band among the options, extending up to 6.39 GHz. It shares the same 28-lead QFN package and control interface as the -1, -2, and -3 models, allowing for pin-compatible design flexibility across different frequency requirements.

Clock Generators, PLLs, Frequency Synthesizers Replacement Considerations

Publicly confirmed substitute part numbers are not available in the provided documentation.