Dual Fractional-N/ Integer-N Frequency Synthesizer

The ADF4252 is a dual fractional-N/integer-N frequency synthesizer that can be used to implement local oscillators (LO) in the upconversion and downconversion sections of wireless receivers and transmitters. Both the RF and IF synthesizers consist of a low noise digital phase frequency detector (PFD), a precision charge pump, and a programmable reference divider. The RF synthesizer has a Σ-Δ-based fractional interpolator that allows programmable fractional-N division. The IF synthesizer has programmable integer-N counters. A complete phase-locked loop (PLL) can be implemented if the synthesizer is used with an external loop filter and voltage controlled oscillator (VCO).

Control of all the 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.

Applications

* Base stations for mobile radio (GSM, PCS, DCS, CDMA, WCDMA)

* Wireless handsets (GSM, PCS, DCS, CDMA, WCDMA)

* Wireless LANs

* Communications test equipment

* CATV equipment

* 3.0 GHz fractional-N/1.2 GHz integer-N

* 2.7 V to 3.3 V power supply

* Separate VP allows extended tuning voltage to 5 V

* Programmable dual modulus prescaler

* RF: 4/5, 8/9

* IF: 8/9, 16/17, 32/33, 64/65