In Chapter 2, a low power K-Band transformer-feedback VCO is designed in 180nm CMOS process. Utilizing transformer-feedback, large signal swings can be achieved. It also achieves low-phase and low power consumption at the same time. The power consumption is 6.7mW at 900mV supply voltage. The phase noise is -103dBc at 1 MHz offset.The result shows that the VCO is suitable for low power applications requiring high signal purity. In Chapter 3, a low power X-Band FMCW Radar synthesizer in 180-nm CMOS Technology. Utilizing a fractional-N synthesizer as the FMCW generator, the VCO is modulated across a range of 90MHz. The chip consumes 30mw with low power consumption divider chain. The measured output phase noise of the synthesizer is -86.5 dBc/Hz at 1 MHz offset.