A 15GHz 4-channel transmit/receive RF core-chip for high SHF wide-band massive MIMO in 5G

A 15GHz 4-channel transmit/receive RF core-chip is presented for high SHF wide-band massive MIMO in 5G. Both phase shifters (PS) and variable gain amplifiers (VGA) with high resolution and high accuracy are integrated in each TX and RX path of the chip. A calibration technique to compensate the error of 6bit PS caused by I/Q mismatch in the poly phase filter is applied. A common gate current steering topology with tail current control is used for 0.25dB step VGA with 20dB range. The core-chip for 15GHz band fabricated in 65nm CMOS process achieved RMS phase control error of less than 2.0deg, RMS amplitude error of less than 0.27dB.