Fully integrated 5GHz CMOS VCOs with on chip low frequency feedback circuit for 1/f induced phase noise suppression

Fully integrated RF CMOS VCOs with on chip low frequency feedback circuit for 1/f induced phase noise suppression are presented. Both Colpitts and differential type VCO circuits are implemented at 5- 6GHz in 0.18 µm CMOS process. The measured Colpitts VCO is working at 5.4-5.75GHz with 1.8V power supply. The core VCO consumes 15mW DC power. The phase noise is -63.3dB/Hz at 10kHz and - 94.5dBc/Hz at 100kHz respectively for the Colpitts oscillator without low frequency feedback, while it is - 69.8dBc/Hz and -98.8dBc/Hz for the oscillator with feedback.