LTC6948IUFD-1#PBF

Clock Generators, PLLs, Frequency Synthesizers Overview

The LTC6948IUFD-1#PBF is a fractional-N phase-locked loop (PLL) synthesizer with an integrated voltage-controlled oscillator (VCO). It operates within a VCO frequency range of 2.24 GHz to 3.74 GHz and supports output frequencies from 0.373 GHz to 3.74 GHz via a programmable divider (O_DIV = 1 to 6). The device features a 4th-order ΔΣ modulator for low spurious performance, an ultralow noise charge pump, and reference input frequencies up to 425 MHz. It utilizes a 28-lead QFN package and requires supply voltages of 3.15V to 3.45V for digital/RF sections and 4.75V to 5.25V for the VCO.

Clock Generators, PLLs, Frequency Synthesizers Feature Summary

• Integrated VCO with frequency range of 2.24 GHz to 3.74 GHz
• Advanced 4th-order ΔΣ modulator eliminates discrete spurious tones
• Programmable output divider (1 to 6) extends frequency coverage down to 0.373 GHz
• Ultralow normalized in-band phase noise floor of –226 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 suffix '#PBF' indicates lead-free packaging compliant with RoHS standards. Confirm the 'I' grade designation corresponds to the –40°C to +105°C operating junction temperature range. Ensure the ordering part number matches the required frequency band option (LTC6948-1) for the intended application design.

Clock Generators, PLLs, Frequency Synthesizers Selection Notes

Select this component when a wide tuning range with minimal spurs is required. The LTC6948-1 variant is specifically designed for lower frequency bands compared to variants -2, -3, or -4. Consider the need for external loop filtering on the TUNE and CP pins. Verify that the system can support the required VCO supply voltage (up to 5.25V) separate from the 3.3V logic supplies.

Clock Generators, PLLs, Frequency Synthesizers Part Context

This part belongs to the LTC6948 family of ultralow noise fractional-N synthesizers. The IUFD-1 suffix identifies the industrial temperature grade, plastic QFN package, and the specific VCO frequency range option (2.24–3.74 GHz). Other variants in the series offer higher frequency ranges up to 6.39 GHz.

Clock Generators, PLLs, Frequency Synthesizers Replacement Considerations

Publicly confirmed substitutes include other members of the LTC6948 family: LTC6948IUFD-2#PBF, LTC6948IUFD-3#PBF, and LTC6948IUFD-4#PBF. These share identical pinouts and functionality but differ in the internal VCO frequency range specifications.