The LMX2491 device is a low-noise, 6.4-GHz wideband delta-sigma fractional N PLL with ramp and chirp generation. It consists of a phase frequency detector, programmable charge pump, and high frequency input for the external VCO. The LMX2491 supports a broad and flexible class of ramping capabilities, including FSK, PSK, and configurable piecewise linear FM modulation profiles of up to 8 segments. It supports fine PLL resolution and fast ramp with up to a 200-MHz phase detector rate. The LMX2491 allows any of its registers to be read back. The LMX2491 can operate with a single 3.3-V supply. Moreover, supporting up to 5.25-V charge pump can eliminate the need of external amplifier, leading to a simpler solution with improved phase noise performance.
|Output frequency (Min) (MHz)|
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|Normalized PLL phase noise (dBc/Hz)|
|1/f noise (10-kHz offset at 1-GHz carrier) (dBc/Hz)|
|Current consumption (mA)|