Capacitor bank design for wide tuning range LC VCOs: 850MHz-7.1GHz (157%)

This paper describes novel design techniques for optimizing the switched-capacitor array in a wide tuning range LC VCO. The switches in the capacitor array are optimally sized to maximize the tuning range. Additionally, parasitic interconnect inductance inherent in the capacitor array is used for increasing the equivalent capacitance value. Based on these proposed techniques, an LC VCO that achieves 157% frequency tuning range from 850MHz to 7.1GHz with phase noise between -107.1 and -119.1 dBc/Hz at 1MHz offset and power dissipation between 3 and 15 mW is designed. The power and phase noise performance of this VCO is at par with the best wideband solutions. However, this is, by far, the largest tuning range obtained for CMOS LC VCOs till date.