Abstract: A technique for enhancing the frequency tuning range for monolithic RF source generation using fully-integrated coupled Voltage-Controlled-Oscillator (VCO) arrays that contain an odd number of VCOs. Fully-monolithic SiGe VCO arrays using on-chip inductor and varactor with on-chip bias current sources have been carefully designed and simulated in IBM 7HP 0.18 ?m BiCMOS technology and taped out for fabrication. The SPICE simulated frequency and phase tuning of the 1-D VCO×5 array is dependent on the edge VCOs termination impedance, the tuning voltages, and the VCO coupling strength. The simulated data suggests that the enhanced tuning range and beam steering can be accomplished using coupled-VCO arrays without needing complex and bulky phase shifters. This design technique imposes no apparent phase noise penalty but can provide simulated RF frequency tuning range of ˜40% and also ˜+/?25° beam steering for active antennas applications.