LTC6948IUFD-4#PBF

The LTC6948IUFD-4#PBF is a high‑performance, wideband fractional‑N RF frequency synthesizer from Analog Devices (formerly Linear Technology). It provides a programmable PLL that locks to a reference clock and generates a high‑frequency RF output with fractional‑N tuning. It is controlled over a serial interface (SPI‑like) and supports an external reference, programmable division ratios, and various output configurations. Typical uses include RF transceivers, clock generation, and instrumentation requiring a precise, programmable RF clock.
Packaging note: The -4#PBF suffix indicates packaging/grade: -IUFD denotes Industrial temperature range; -PBF denotes a RoHS‑compliant Plastic Lead Frame package. Exact package type and options are listed in the ADI packaging matrix.
Usage basics: provide VDD, supply the reference, program the N and fractional settings via the serial port, and select an appropriate loop filter per the datasheet. For detailed pinout, specs, and recommended circuits, consult the LTC6948 data sheet on Analog Devices’ website.

I don’t have the exact pin‑by‑pin datasheet memorized, but LTC6948 family parts are high‑performance PLL clock synthesizers. Typical features you should expect:
- Fully integrated fractional‑N (and integer‑N) phase‑locked loop synthesizer
- Programmable dividers (N, R) for wide output frequency range
- External reference input with selectable reference divider and low jitter
- Flexible outputs (single‑ended and differential clock outputs) with low jitter and low skew
- SPI‑type serial control interface for programming, readback, and lock detect
- Phase noise/fast settling suitable for RF clock generation; lock detect and robust holdover
- Power‑down/soft‑start options for power management
- Operates from a modest supply (typical 2.7–3.6 V range)
- RoHS compliant packaging (LQFN/ QFN family, e.g., IUFD variants)
For exact electrical specs, package details, and the precise features of the LT6948IUFD‑4#PBF variant, please refer to the current datasheet.

Pb-free, RoHS-compliant package: 32‑lead Plastic Quad Flat Pack (LQFP).

- Pin count: 20 pins (in the IUFD package variant)
- Function: Wideband RF PLL synthesizer with an integrated VCO and prescalers; provides fractional-N frequency synthesis and RF output buffers.

Analog Devices, Inc. (ADI) is the manufacturer. It is a U.S.-based multinational semiconductor company that designs and manufactures analog, mixed-signal, and DSP integrated circuits. The LTC6948 line originated with Linear Technology, which was acquired by ADI.

Applications: RF/microwave frequency synthesis and local-oscillator generation for wireless transceivers; programmable VCO/PLL sources for RF front-ends; test and measurement equipment as precise, low-noise RF sources; instrumentation requiring programmable reference frequencies; and clock generation/distribution in high-speed digital systems.