A 34% tuning range CMOS VCO with linear frequency tuning

A CMOS voltage controlled oscillator(VCO) with additional parallel resistors in its LC resonator has been proposed to improve the tuning (frequency-to-voltage) linearity and reduce the tuning sensitivity KVCO. The VCO is linearly tunable from 806 to 1,113 MHz with a 34% tuning range controlled linearly by the tuning voltage. The phase noise of the VCO is -100.4 dBc/Hz at 100-kHz offset frequency from 903 MHz carrier. The supply voltage was 1.8 V with the current of 2.5 mA flowing through the differential core. The chip size is 0.815 times 0.680 mm², which has been fabricated in a standard 180-nm CMOS technology.