This paper reports an LC-based digitally controlled oscillator (DCO) in 65 nm CMOS, key component in a digital phase locked loop, with an enhanced frequency resolution and extended tuning range. It has a center frequency of 5.8 GHz and a tuning range of 1800 MHz. The finest frequency step is about 20 kHz. The oscillator exhibits a phase noise of -100 dBc/Hz at 100 kHz frequency offset from 4.9 GHz. The DCO draws 4 mA current from 1.8 V supply.