A 28GHz 4-Channel Transmit/Receive RF Core-Chip with Highly-Accurate Phase Shifter for High SHF Wide-Band Massive MIMO in 5G

This paper presents a 28GHz 4-channel transmit/receive RF core-chip for high SHF wide band massive MIMO in 5G. The RF core-chip integrate phase shifters (PS) and variable gain amplifiers (VGA) with high control accuracy. The structure of PS is chosen for active vector sum type to realize small chip area. In order to improve the accuracy of active PS, a new control method to suppress the input impedance variation of the gain control block is proposed. The VGA uses a common gate current steering topology with tail current control to enhance the control resolution and accuracy. The RF core-chip for 28GHz band fabricated in 65nm CMOS process achieves RMS phase control error of less than 2.1deg. rms and RMS amplitude control error of less than 0.15dB rms.