小数N分频合成器 Fractional-N Frequency Synthesizer
GENERAL DESCRIPTION
The ADF4153 is a fractional-N frequency synthesizer that implements local oscillators in the upconversion and downconversion sections of wireless receivers and transmitters. 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, FRAC, and MOD registers define an overall N divider N= INT+ FRAC/MOD. In addition, the 4-bit reference counter R counter allows selectable REFIN frequencies at the PFD input. A complete phase-locked loop PLL can be implemented if the synthesizer is used with an external loop filter and a voltage controlled oscillator VCO.
