Differential cross coupled voltage controlled oscillator with transformer tuning is presented here for millimeter wave (mmw) application. Here Tuning is done by on chip octagonal transformer which is used as inductive element in LC tank. Proposed scheme provides wide Frequency Tuning Range (FTR) up to 7 GHz of bandwidth and gives low phase noise as compared to inductor based oscillator design. In this method transformer tuned VCO is implemented in UMC 65 nm CMOS Technology which gives FTR from 55 GHz to 62.4 GHz with phase noise variation -116.5 to -114.5dBc/Hz at 10 MHz offset.