In this paper, we fabricated an 1.8 ㎓ differential VCO using a commercial 0.5 ${mu}{ extrm}{m}$ SiGe BiCMOS process technology, The fabricated VCO consumes 16 ㎃ at 3 V supply voltage and has a 1.2 $ imes$ 1.6 <TEX>$mm^2$TEX>chip area. A phase noise measured at 100 KHz offset carrier is -110 ㏈c/Hz and a tuning range is 1795 MHz~1910 MHz when two varactor diodes are biased from 0 V to 3 V.