A fully integrated LC VCO with 1V voltage supply for wireless sensor network applications

A fully integrated LC VCO with 1V low voltage supply, applied in the frequency synthesizer for wireless sensor network applications, is designed and implemented in TSMC 0.18μm RF/MS CMOS process with low power consumption and good phase noise performance. To address the problem caused by low voltage, the structure of VCO is carefully selected. A 4 bit switched capacitor array is used to widen tuning range without worsen the phase noise performance. Besides, a 4 bit switched tail current source array is used to achieve power consumption adapted to the desired operating scenario. Second harmonic filter technology is taken to improve phase noise performance. The VCO designed in this paper has good phase noise performance and low power consumption by optimization. The chip size is 850μm×680μm. Post simulation results show that the tuning range is 4.48~6.52GHz and power consumption of VCO core circuit changes from 1.8mW to 4.6mW according to the control code. The phase noise is between -106.7dBc/Hz and -117.5dBc/Hz at 1MHz offset frequency.