An enhanced phasor-sum method for accurate built-in relative phase and amplitude detection in beamforming phased arrays

Abstract

An accurate phasor-sum method is proposed for the built-in detection of relative phase and amplitude between neighboring RF chains in phased array systems. The phasor sum of two RF signals provides a distinct amplitude-phase trigonometric relationship, from which the relative phase can be determined solely by the signal amplitudes. However, the amplitude distortion, attributed from the impedance mismatch or nonlinearity of detection circuits and devices, introduces considerable phase error. In our proposed method, the amplitude distortion error is first eliminated and then the phase error is significantly reduced. The measurement results of a 3-GHz four-chain RF array demonstrate that the root-mean-square phase error is less than 3.2° over the entire 0° to 180° range and the power error is less than 0.3 dB.