A dual-band LC VCO using a switched current source for IMT-Advanced and UWB applications

This paper presents a dual-band CMOS LC voltage controlled oscillator (VCO) with a switched current source for 3.4-3.6 GHz IMT-Advanced and 4.2-4.8 GHz UWB applications. To accomplish dual-band operation, reconfigurable LC tank is adopted, and a switched current source has been used to guarantee robust start-up condition. Bias filters are used in VCO to suppress reference current noise and dynamic transient effects on the bias line. The simulated phase noises at 1 MHz offset frequency are -124 dBc/Hz at 3.6 GHz and -121 dBc/Hz at 4.8 GHz, respectively. Designed in TSMC 0.13 μm process, the VCO current dissipation is 2.8 mA at UWB band and 3.9 mA at IMT-Advanced band from 1.2 V power supply.