A 4-GHz VCO for Multiband OFDM UWB systems

A 4-GHz VCO for Multiband OFDM ultra-wide-band system is presented. Methods for maintaining a good phase noise under reasonable power consumption for the 4 GHz VCO are presented. The design was fabricated in 0.18-μm CMOS process. The measured VCO phase noise at 1 MHz offset from 4 GHz is lower than −126 dBc/Hz at 1.5 V supply voltage and is lower than −120 dBc/Hz even at 1 V supply. The VCO has an output frequency range from 3.1-GHz to 4.1-GHz, and consumes 4.7 mW at 1.5V.