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.