Compact low loss 1-bit controlled passive phase shifter for 4-channel RF phased array

Abstract

A simplified 4-channel phased array structure that uses one stage of switched type passive phase shifter and structures of phase shifters using 65-nm CMOS process are described. In many case, one channel of phased array has phase shifter that can control the phase with more than eight states. However, in certain case, required phase states can be reduced. At this paper, different with typical phased array, each channel of proposed phased array needs only two kinds of phase states. Fewer required states makes loss of phase shift-er improved. Therefore, this modified structure makes total performance of the system better. Besides, sim-plified one stage switched line type SPDT 180° passive phase shifter for this phased array structure is present-ed. The proposed phase shifter reduces the number of required elements as compared with conventional SPDT phase shifter due to the reactance sharing method. This SPDT 180° phase shifter is designed and im-plemented targeting 60 GHz application, and conventional 90° phase shifter for the system are also designed additionally. The proposed 180° phase shifter features average -4.15 dB of measured gain, 0.88 dB of gain error, 175.5° of phase difference, and 4.4° phase error. Chip area is 0.04$mm^2$ without pad. The significance of this paper is that it reports compact low loss one stage phase shifter for 4 channel phased array.