Differentially tuned LC-VCO using modified anti-parallel structure

This paper presents a new differentially tuned LC-VCO using a modified anti-parallel. The proposed LC-VCO has lower phase noise and better robustness to the common-mode noise than the previous differentially tuned LC-VCO using the anti-parallel structure. The proposed LC-VCO is implemented using SiGe BiCMOS process. It is tunable from 4.25 to 4.43 GHz and the measured phase noise is -103 dBc/Hz at 100 kHz offset and -119 dBc/Hz at 1 MHz offset over the entire tuning range. Also, its CMRR characteristic is improved about 2dB. Its core current is 1.7 mA at 2.5V supply voltage.