14-mW 5-GHz frequency synthesizer with CMOS logic divider and phase-switching dual-modulus prescaler

A 5-GHz frequency synthesizer for Zigbee (IEEE 802.15.4) was implemented. It consumes only 14mW adopting CMOS logic divider and phase-switching dual-modulus. A 2nd loop filter is internally embodied to reduce external components. The phase switching is made between the 45deg spaced output phases to reduce the power consumption and improve the robustness of circuit. This synthesizer was fabricated in 0.18-mum technology; it consumes 8mA at 1.8V and offers 100kHz-loop bandwidth and -103dBc/Hz at an offset of 1MHz. the lock time is 30mus. The PLL output tuning range is 11% from 2.37GHz to 2.66GHz