A 2-V 1.8-GHz fully integrated CMOS dual-loop frequency synthesizer

A 2-V 1.8-GHz fully integrated CMOS dual-loop frequency synthesizer is designed in a standard 0.5-mum digital CMOS process for wireless communication. The voltage-controlled oscillator (VCO) required for the low-frequency loop is designed using a ring-type VCO and achieves a tuning range of 89\% from 356 to 931 MHz and a phase noise of -109.2 dBc/Hz at 600-kHz offset from 856 MHz. With an active chip area of 2,000 x 1000 mum(2) and at a 2-V supply voltage, the whole synthesizer achieves a tuning range from 1.8492 to 1.8698 GHz in 200-kHz steps with a measured phase noise of -112 dBc/Hz at 600-kHz offset from 1.86 GHz. The measured settling time is 128 mus and the total power consumption is 95 mW