60-GHz CMOS dual polarized MIMO receiver IC for Gbps short-range wireless communication

Abstract

This dissertation is about a 60-GHz band CMOS dual polarization MIMO receiver IC for short-range wireless communication with Gbps data rate. For wireless VR/AR, it is necessary to be able to transmit and receive video with a resolution of 4K or higher without a codec, and the corresponding data rate is 12 Gbps or higher. Since the 60-GHz band has a channel bandwidth of 2.16 GHz and a wide bandwidth of up to 14 GHz is allocated worldwide, it is very suitable for this application. In addition, if the dual polarization MIMO technique using the two orthogonal polarizations of the antenna is used, two data can be transmitted and received with a single antenna size using the dual polarization antenna, so the number of antennas can be reduced by half compared to the single polarization MIMO technique. Moreover, there is an advantage that the channel capacity can be doubled while using the same frequency band. However, performance of an actual dual-polarized MIMO system rapidly deteriorates due to misalignment between the transmit and receive antennas, finite cross-polarization isolation of the dual-polarized antenna, and increased cross-polarization leakage due to multipath. Therefore, a polarization leakage cancellation technique for eliminating cross-polarization leakage is necessarily required. In this dissertation, we proposed a polarization alignment technique capable of eliminating cross-polarization leakage even with large cross-polarization signals. And by extending it to a phased array, the polarization leakage due to multipath was also eliminated. This dissertation consists of 6 chapters. In Chapter 2, the implementation of a 60-GHz band heterodyne IQ demodulator for receiver integration was described. The heterodyne IQ demodulator includes IQ gain and phase calibration circuits, which achieves 44 dBc of image rejection. In Chapter 3, the polarization alignment technique proposed in this dissertation was introduced and analyzed mathematically. The polarization alignment technique proposed in this study improves the degraded cross-polarization isolation by aligning the V and H polarizations through vector modulation of the V and H polarization signals. Compared to the reported polarization leakage cancellation techniques, leakage cancellation is possible even when the cross-polarization signal is larger, and it can be implemented with low power and small area. In Chapter 4, a 60-GHz RF polarization aligner was designed and implemented to verify the proposed polarization alignment technique, and a dual polarized antenna was fabricated and integrated with an antenna and package (AiP). In Chapter 5, based on the results analyzed in Chapter 4, the proposed technique was extended to a phased array to implement a receive phased array IC and AiP composed of two dual polarized antennas. As a result of the measurement, cross-polarization isolation of more than 20 dB for both V- and H-polarization paths in channel 1 of the 60 GHz band was achieved thanks to the proposed polarization alignment technique even though the transmit and receive antennas were misaligned from 0 to 90°. The proposed receive array is the first receive phased array to which polarization leakage cancellation technique is applied while supporting dual polarization MIMO in the 60 GHz band. Finally, Chapter 6 summarizes and concludes the dissertation.