A novel phase-shifterless beam steering method for RF phase arrays using monolithic 1-D coupled-VCOs with integrated MOSFET switches

A fully monolithic 1-Dimensional (1-D) AC-coupled Voltage-Controlled-Oscillators (VCOs) network design for phased-array applications will be presented in this paper. This radio-frequency (RF) VCO array integrates on-chip inductors, varactors, and bias current sources and it contains an odd number of VCOs (i.e., 3 or 5, etc.) AC-coupled through on-chip switchable resistor networks with MOSFETs. Realistic circuit simulations in IBM 7HP 0.18μm BiCMOS design kit indicate promising results of the 1-D coupled-VCO array. Based on the simulation data and the current measured data that has been consistent with the simulation results, our design is able to control the phasing of this on-chip VCO-array by means of tuning the edge elements and/or by varying the coupling strength via the resistive coupling network digitally controlled with the MOS switches. This AC-coupled 1-D VCO array shows some great potential for RF active antennas applications to perform wide angle beam steering without the need for bulky phase shifters for the highly utilized S-band.