Chip design of a 5.6-GHz 1-V wide tuning range frequency synthesizer with Gm-boosting Colpitts VCO for biomedical application

A 5.6-GHz 1-V wide tuning range frequency synthesizer with a gain-boosting Colpitts voltage-controlled oscillator (VCO) is fabricated in TSMC 0.18 um CMOS process. In this prototype, there are two important features. First, a 1-V gain-boosting Colpitts LC VCO circuit is adopted to reduce phase noise and power consumption. Second, a class-AB current mode logic (CML) circuit is utilized in first divider stage to deal with the high frequency signal. At the supply voltages of 1-V for VCO and 1.8-V for digital circuits, measured results achieve that the VCO output frequency is tunable from 5.13~5.98 GHz corresponding to 15.4% and the locked phase noise is -105.83 dBc/Hz at 1MHz from 5.15 GHz. The power consumption is 5.6 mW and including pads, the chip area is 0.632 (0.89 × 0.71) mm². This chip design low power consumption for biomedical application.