ADF4251:  Lowest Phase Noise PLL Synthesizer using Fractional-N Technology

The ADF4251 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 ...More

ADF4251:  Lowest Phase Noise PLL Synthesizer using Fractional-N Technology

Product Description

The ADF4251 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 ADF4251 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 ADF4251 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.

Evaluation board with software is available. There is also a full data sheet with performance graphs. Additionally, the device is featured on ADIsimPLL Synthesizer simulation tool.

Features

  • Sigma-delta based fractional-N technology ensures superior Phase Noise and spurious performance is maintained over temperature
  • Hardware and Software Power-Down
  • Flexibility of programmable fractional-modulus ensures exact output frequencies can be synthesized.
  • 0.1 - 3.0GHz Fractional-N / 0.05 - 1.2GHz Integer-N PLL's
  • 3 wire Serial Interface with 1.8V logic compatibility
  • 250MHz REFIN Frequency
  • 8 x Programmable charge pump currents
  • PFD frequencies up to 30MHz allow faster settling and lower phase noise.
  • Supported on ADIsimPLL software design tool
  • Available in 4x4mm Chipscale package
  • 2.7 - 3.3V Power Supply with separate VP to 5V

Diagrams

ADF4251 Diagram
Functional Block Diagram for ADF4251

Specifications

Type Dual Fractional-N
Max RF Input (MHz) 3000MHz
Norm Phase Noise (dBc/Hz) 103dBc
Max REFin (MHz) 150MHz
RF Prescalers 4/5,8/9
Supply Current (max) 13mA
Package 24-Lead CSP

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Part# Type Max RF Input (MHz) Output Frequency Range Norm Phase Noise (dBc/Hz) Max REFin (MHz) RF Prescalers Supply Current (max) Package Price* (1000-4999)
AD809 Synthesizer - 155.52 MHz -219 19.44 - 17 16-Lead SOIC $3.85
ADF4001 Single Integer-N 200 - -214 104 n/a 4.5 16-Lead TSSOP, 20-Lead CSP $1.72
ADF4002 Single Integer-N 400 - -222 300 n/a 5 16-Lead TSSOP, 20-Lead CSP $1.97
ADF4007 Single Integer-N 7500 - -219 240 N counter = 8/16/32/64 13 20-Lead CSP $2.16
ADF4106 Single Integer-N 6000 - -219 300 16/17, 32/33, 64/65, 8/9 13 16-Lead TSSOP, 20-Lead CSP $2.16
ADF4107 Single Integer-N 7000 - -219 250 16/17, 32/33, 64/65, 8/9 13 16-Lead TSSOP, 20-Lead CSP $2.67
ADF4108 Single Integer-N 8000 - -219 250 16/17, 32/33, 4/5, 64/65, 8/9 17 20-Lead CSP $3.34
ADF4110 Single Integer-N 550 - -215 104 16/17, 32/33, 64/65, 8/9 4.5 16-Lead TSSOP, 20-Lead CSP $2.28
ADF4111 Single Integer-N 1200 - -215 104 16/17, 32/33, 64/65, 8/9 4.5 16-Lead TSSOP, 20-Lead CSP $2.28
ADF4112 Single Integer-N 3000 - -215 104 16/17, 32/33, 64/65, 8/9 6.5 16-Lead TSSOP, 20-Lead CSP $2.28
ADF4113 Single Integer-N 4000 - -215 104 16/17, 32/33, 64/65, 8/9 8.5 16-Lead TSSOP, 20-Lead CSP $2.28
ADF4113HV Single Integer-N 4000 - -212 104 16/17, 32/33, 64/65, 8/9 11 16-Lead TSSOP, 20-Lead CSP $2.49
ADF4116 Single Integer-N 550 - -211 100 8/9 4.5 16-Lead TSSOP $2.28
ADF4117 Single Integer-N 1200 - -213 100 32/33 4.5 16-Lead TSSOP $2.28
ADF4118 Single Integer-N 3000 - -216 100 32/33 6.5 16-Lead TSSOP $2.28
ADF4153 Single Fractional-N 4000 - -213 250 4/5, 8/9 12 16-Lead TSSOP, 20-Lead CSP $2.28
ADF4154 Single Fractional-N 4000 - -213 250 4/5, 8/9 12 16-Lead TSSOP, 20-Lead CSP $2.28
ADF4156 Single Fractional-N 6000 - -213 250 4/5, 8/9 12 16-Lead TSSOP, 20-Lead CSP