Lowest Phase Noise PLL Synthesizer using Fractional-N Technology
The ADF4252 Fractional-N Synthesizer when combined with a VCO and loop filter forms a complete phased locked loop (PLL). This solution from ADI creates state-of-the-art LO's (local oscillator) for the upconversion and downconversion of RF signals in Wireless applications. The ADF4252 can provide the LO for both RF and IF sections. The RF section incorporates Fractional-N techniques while the IF section uses integer-N techniques. The ADF4252 PLL consists of a low noise digital phase frequency detector (PFD), a precision charge pump, a programmable reference divider, programmable integer registers. Programmable modulus fractional interpolator.
-103dBc/Hz In-band Phase Noise performance for GSM 1800MHz conditions (as an example) is approximately a 15dB improvement over the ADI best Integer-N PLL Phase Noise (ADF4106) and a 10dB improvement over competing F-N PLL products available today. Fractionality will provide for higher PFD reference which will allow wider loop bandwidth for fast lock times. This product is targeted principally at Handset and infrastructure applications requiring low phase noise, fast settling, small channel steps at high output frequencies.
Sales Collateral: Full data sheet with performance graphs and evaluation board and software available, featured on ADIsimPLL Synthesizer software simulation tool
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At least one model within this product family is in production and available for purchase. The product is appropriate for new designs but newer alternatives may exist.
This page contains ordering information for the evaluation board used to evaluate the ADF4252 Lowest Phase Noise PLL Synthesizer using Fractional-N Technology.
Recommended Linear Regulators
Recommended Divide-by-4 Prescaler
- For a low noise, low power, fixed RF block , we recommend the ADF5001 .
Recommended PLL Active Filter
- For an ultralow noise, rail-to-rail amplifier , we recommend the OP184 .
Ask the Applications Engineer—30: PLL SYNTHESIZERS
(Analog Dialogue, Vol. 36, No. 3, May-July, 2002)