An ultra-low-power CMOS complementary VCO using three-coil transformer feedback

An ultra-low-power VCO based on the complementary cross-coupled structure with the three-coil transformer feedback is proposed and realized in 0.18 µm CMOS. This VCO has a 1 MHz offset phase noise of −118.5 dBc/Hz and consumes only 0.66 mW dc consumption. The FOM of this VCO is better than −195 dBc/Hz form 8.09 to 8.42 GHz, and the highest FOM of −198.6 dBc/Hz occurs at 8.2 GHz. The chip size is 530 × 430 µm².