An area-efficient 3.5GHz fractional-N frequency synthesizer with capacitor multiplier in millimeter-wave gigabit wireless communication

This paper presents a CMOS 65 nm sigma-delta frequency synthesizer with an embedded capacitor multiplier to support the multi-gigabit baseband data rate for millimeter-wave wireless communication. The capacitor multiplier achieves an equivalent value of 540 pF and save 90 % of area for the main capacitor. It is optimized for noise performance to provide the phase noise of -117 dBc/Hz from voltage-controlled oscillator (VCO) at 1 MHz frequency offset of 3.456 GHz. The current consumption for the multiplier is 327 uA. The VCO covers 3.5 GHz with 1 GHz frequency range to supports multiple data rates (3.52 Gbps, 3.456 Gbps and 2.97 Gbps) in IEEE 802.15.3c. Moreover, a flexible reference frequency from 10 MHz to 40 MHz can be selected because of the feature given by fractional-N PLL architecture. The adjustable reference frequency therefore provides more design margin for system integration. With this area-efficient design, the synthesizer can be integrated into the 60 GHz transceiver as a baseband solution.