PLL Frequency Synthesizer

  
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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 i
PLL Frequency Synthesizer - schematic

ncorporates 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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