High Resolution 6 GH Fractional-N Frequency Synthesizer

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.

Control of all 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

* Satellite communications terminals, radar equipment

* Instrumentation equipment

* Personal mobile radio (PMR)

* Base stations for mobile radio

* Wireless handsets

* 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