A dual-band monolithic voltage-controlled oscillator (VCO) has been fabricated by using the 0.18 mum 1P6M CMOS technologies. The switching transistors concept used in the tank circuit realizes the dual-band VCO operation. In order to reduce the phase noise, the pMOS transistors were used in the VCO design. The dual-band VCO demonstrates the phase noise (100 kHz offset) of -98 dBc/Hz at 2.6 GHz and -91 dBc/Hz at 5.2 GHz. (C) 2003 Elsevier Ltd. All rights reserved.