A class-C VCO based ∑-△ fraction-N frequency synthesizer with AFC for 802.11ah applications

A 1.4-2 GHz phase-locked loop （PLL） ∑-△ fraction-N frequency synthesizer with automatic fre- quency control （AFC） for 802.1 lah applications is presented. A class-C voltage control oscillator （VCO） ranging from 1.4 to 2 GHz is integrated on-chip to save power for the sub-GHz band. A novel AFC algori...

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