LTC6948IUFD-4#PBF

Clock Generators, PLLs, Frequency Synthesizers Overview

The LTC6948IUFD-4#PBF 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). The device features a 4th-order delta-sigma modulator for low spurious performance, an input reference frequency up to 425 MHz, and an 18-bit fractional denominator. Electrical specifications include –226 dBc/Hz normalized in-band phase noise floor and –274 dBc/Hz normalized 1/f noise. It utilizes a 28-lead QFN package and requires supply voltages of 3.3 V for digital/RF sections and 5 V for the VCO and charge pump.

Clock Generators, PLLs, Frequency Synthesizers Feature Summary

• Integrated VCO with frequency range of 4.20 GHz to 6.39 GHz
• Advanced 4th-order delta-sigma modulator eliminates fractional spurs
• Programmable output divider (O_DIV) ranging from 1 to 6
• Normalized in-band phase noise floor of –226 dBc/Hz

Clock Generators, PLLs, Frequency Synthesizers Applications

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

Clock Generators, PLLs, Frequency Synthesizers Procurement Notes

Verify the specific suffix #PBF indicates lead-free tube packaging when sourcing. Confirm the -4 variant matches the required 4.20 GHz to 6.39 GHz VCO range. Ensure the ordering information aligns with the 28-lead QFN physical dimensions and thermal requirements specified in the datasheet.

Clock Generators, PLLs, Frequency Synthesizers Selection Notes

Select the LTC6948IUFD-4#PBF when the application requires a VCO operating between 4.20 GHz and 6.39 GHz. Consider the output divider setting if lower output frequencies are needed, as the device supports ranges down to 0.700 GHz. Verify that the system can accommodate the separate 3.3 V and 5 V power supply rails required for optimal performance.

Clock Generators, PLLs, Frequency Synthesizers Part Context

This component belongs to the LTC6948 family of ultralow noise fractional-N synthesizers. The -4 suffix designates the specific internal VCO tuned for the highest frequency band among the four available options. Other variants in the series cover lower frequency ranges such as 2.24 GHz to 3.74 GHz or 3.84 GHz to 5.79 GHz.

Clock Generators, PLLs, Frequency Synthesizers Replacement Considerations

Direct replacements within the same family include the LTC6948IUFD-1#PBF, LTC6948IUFD-2#PBF, and LTC6948IUFD-3#PBF, which share identical pinouts but offer different VCO frequency ranges.