GENERAL DESCRIPTION
The ADF4157 is a 6 GHz fractional-N frequency synthesizer with a 25-bit fixed modulus, allowing subhertz frequency resolution at 6 GHz. It consists of a low noise digital phase frequency detector (PFD), a precision charge pump, and a programmable reference divider. There is a Σ-Δ based fractional interpolator to allow programmable fractional-N division. The INT and FRAC values define an overall N divider, N = INT + (FRAC/225). The ADF4157 features cycle slip reduction circuitry, which leads to faster lock times without the need for modifications to the loop filter.

FEATURES
   RF bandwidth to 6 GHz
   25-bit fixed modulus allows subhertz frequency resolution
   2.7 V to 3.3 V power supply
   Separate VP allows extended tuning voltage
   Programmable charge pump currents
   3-wire serial interface
   Digital lock detect
   Power-down mode
   Pin compatible with the following frequency synthesizers:
      ADF4110/ADF4111/ADF4112/ADF4113/
      ADF4106/ADF4153/ADF4154/ADF4156
   Cycle slip reduction for faster lock times

APPLICATIONS
   Satellite communications terminals, radar equipment
   Instrumentation equipment
   Personal mobile radio (PMR)
   Base stations for mobile radio
   Wireless handsets