Low-voltage, low-power and highly-tunable 1.8GHz CMOS LC voltage controlled oscillator

A fully integrated 1.8 GHz low phase noise LC-tank VCO is presented and analyzed. The phase noise of the oscillator has been greatly reduced by means of integrated source degeneration inductors. The phase noise achieved is -105, -123 and -138 dBc/Hz at 100 KHz, 600 KHz and 3 MHz offsets respectively from the carrier frequency of 1.8 GHz, with 1.8 V power supply voltage and giving a low power consumption of only 2.8 mW by considering the proposed VCO topology, which consumes less power than the conventional differential transconductor pair. A 15.8% broad tuning range has been achieved by using the standard mode PMOS varactors in the designed voltage controlled oscillator architecture. The tunability of the designed VCO covers 290 MHz, from 1.69 GHz up to 1.98 GHz with a VCO gain K_vco of 320 MHz/V.