Low phase noise and low power CMOS LC voltage controlled oscillator for 5-GHz WLAN applications

A low phase noise and highly tunable 5.15-GHz LC VCO is presented and analyzed. The phase noise achieved is -97 and -118 dBc/Hz at 100 KHz and 1 MHz offsets respectively from the carrier frequency of 5.15 GHz, with 2.5 V power supply voltage and giving a low power consumption of 11.4 mW by considering the proposed oscillator topology, which exhibits less power consumption than the traditional VCO using the classical differential transconductor pair. A broad tuning range has been achieved by means of standard mode PMOS varactors. The tunability of the designed VCO covers 780 MHz, from 4.42 GHz up to 5.2 GHz. The proposed VCO is fully operational under variable conditions including temperature and supply voltage variations.