A 1.8 V fully integrated dual-band VCO for zero-IF WiMAX/WLAN receiver in 0.18 /spl mu/m CMOS

A fully integrated dual-band voltage-controlled oscillator (VCO) that can cover 4.8-5.8 GHz and 6.8-7.2 GHz for a zero-IF WiMAX and WLAN receiver is proposed and implemented in 0.18 mum CMOS technology with 1.8 V supply voltage. The two major continuous frequency bands for these two standards are 2.4-2.9 GHz and 3.4-3.6 GHz, thus a differential cross-coupled inductance-capacitance (LC) tank VCO with up to 20% tuning range is proposed to cover twice the desired bands in order to avoid load pulling between VCO frequency and RF frequency. The desired frequency bands are obtained by using a divider after the VCO. The switching between two bands is implemented by using two capacitor arrays. A phase noise of -120.7dBc/Hz at 1 MHz offset frequency is demonstrated for an oscillation frequency of 4.84 GHz. The average power consumption of this VCO is 8.1 mW. This VCO is developed as an IP (intellectual property) to be used in a fully integrated CMOS multi-standard WiMAX/WLAN radio allowing seamless roaming of handheld mobile devices between hotspots in future wireless metropolitan area network (WMAN)