Fractional-N Frequency Synthesizer

The ADF4154 is a fractional-N Frequency Synthesizer that implements local Oscillators in the up conversion and down conversion sections of Wireless receivers and transmitters. It consists of a low noise digital phase frequency detector (PFD), a precision Charge Pump and a programmable reference divider. There is a - based fractional interpolator to allow programmable fractional-N division. The INT, FRAC, and MOD Registers define an overall N divider (N = (INT + (FRAC/MOD))). In addition, the 4-bit reference Counter (R counter) allows selectable REFIN frequencies at the PFD input. A complete phase-locked loop (PLL) CAN be implemented if the synthesizer is used with an external loop Filter and a voltage controlled Oscillator (VCO).
A key feature of the ADF4154 is the fast-lock mode with a builtin Timer The user CAN program a predetermined count-down time value so that the PLL will remain in wide bandwidth mode, instead of having to control this time externally.
Control of all on-chip Registers is via a simple 3-wire Interface The device operates with a power supply ranging from 2.7 V to 3.3 V, and CAN be powered down when not in use.
By Analog Devices, Inc.