In this thesis a digitally controlled oscillator at 20 GHz is designed to have very fine tuning resolution. Fine resolution is important to obtain better performing phase locked loops. Three designs are explored in order to achieve high resolutions, obtaining resolutions of 30 MHz, and then progressing to 100 kHz in the final design. The low inductance decreased the tank resistance and gain of the oscillator and prevented the final design from working on chip, although extracted simulations worked fine. The final design however is worth trying again possibly using larger transistors or a more
advanced technology than 0.13 micron CMOS to provide more gain. This thesis also explored the limit of having an oscillator with a wide tuning range and fine resolution simultaneously.