Design of a 40GHz PLL frequency synthesizer with wide locking range ILFD in 65nm CMOS

A 40GHz PLL synthesizer is designed in 65nm CMOS for a 60GHz sliding-IF RF transceiver for IEEE 802.11ad applications. For wide locking range, ILFD employs a 5-bit switched capacitor array and a inductive peaking at the injection FET. The ILFD's locking range is wider than the VCO's tuning range, which ensures the PLL can safely lock across the VCO's full tuning range. Also, a tuned buffer with a boosted Q load is employed to minimize unwanted interaction between the VCO and ILFD's operating frequencies, which also helps widen the PLL's locking range. The PLL synthesizer is designed in 65nm CMOS and its die area is 1.0×1.1mm2.