ADF4159:  Direct Modulation/Fast Waveform Generating, 13 GHz, Fractional-N Frequency Synthesizer

The ADF4159 is a 13 GHz, fractional-N frequency synthesizer with modulation and both fast and slow waveform generation capability. The part uses a 25-bit fixed modulus, allowing subhertz frequency resolution.

The ADF4159 consists of a low noise digital phase frequency detector (PFD), a precision charge pump, and a programmable reference divider. The Σ-Δ-based fractional interpolator allows programmable fractional-N division. The INT and FRAC registers define an overall N divider as N = INT + (FRAC/225).

The ADF4159 can be used to implement frequency shift keying (FSK) and phase shift keying (PSK) modulation. Frequency sweep modes are also available to generate various waveforms in the frequency domain, for example, sawtooth and triangular wave-forms. The ADF4159 features cycle slip reduction circuitry, which enables 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 ADF4159 operates with an analog power supply in the range of 2.7 V to 3.45 V and a digital power supply in the range of 1.62 V to 1.98 V. The device can be powered down when not in use.

Applications

• FMCW radars
• Communications test equipment
• Communications infrastructure