The current trend in the state-of-the-art oscillators achieves low phase noise performance. Such stringent performance is demanded in modern Communication Systems. This thesis proposes the design of a CMOS oscillator achieving the ultra-low phase noise. This design is based on TSMC 40 nm technology, the supply voltage is 1.1 V, and the oscillation frequency is f_start=6.65 GHz and f_stop=7.58 GHz, the tuning range is calculated to be 13 % with the Phase Noise@ 1 MHz(normalized to 10 GHz) varies from -128.1 dBc/Hz to -130.4 dBc/Hz and Figure of Merit varies from 188.0 dBc/Hz to 190.0 dBc/Hz, consuming average power of 95 mW and the f_corner is 250 kHz. Since the chip is still in fabrication and the final result only includes the simulation result. Further work involves the measurement and performance validation.