# Review of Recent Phased Arrays for Millimeter-Wave Wireless Communication
## 2 Millimeter-Wave Antenna Array for 5G Communication
### Millimeter-Wave Phased Arrays for 5G Access Terminals
#### 2.2.2 Millimeter-Wave RFIC Phased Arrays  
Along with the current IC-based packaging technology, there also exists an integrated analog-based phased-array solution proposed for 5G mm-wave communication [52; 53; 54; 55; 56; 57; 58; 59; 60; 61; 62; 63; 64; 65; 66; 67; 68; 69]. In [53], a 32-element RFIC-based phased array operating at 28 GHz, which supports dual polarization and accurate beam-scanning capability with the advantage of high output power, was presented. The proposed RFIC reported in [53] is compact and efficient with respect to size, and scaled, which supports dual polarization at the Tx and Rx with in-packaged array technology. The proposed RFIC with a 32-transceiver (TRx) element phased array is implemented using a 0.13-\(\upmu\)m-size SiGe BiCMOS (Bipolar Complementary Metal Oxide Semiconductor) process, as presented in Figure 19a. A packaged module of the proposed four ICs with 128 elements (32 each in four ICs) and 64 dual-polarized antenna elements providing two 64-element concurrent beams was proposed in [65] with a measured beam-scanning range of \(\pm\)50\({}^{\circ}\) with a 1.4\({}^{\circ}\) resolution, as shown in Figure 19b. Figure 19: (**a**) RFIC architecture and schematic block diagram of 16-element phased array. (**b**) 64-element TX phased-array angular beam-scanning of \(\pm\)50\({}^{\circ}\) (Redrawn from [53; 65])In [54], an IC-based transceiver with a flip-chip package phased array operating at 28-32 GHz was proposed for 5G mm-wave communication. The proposed IC chip comprised four separate TRx channels along with 6-bit phase shifters and a 4-bit 14-dB gain control. Figure 20a shows the block diagram of 2 \(\times\) 2 TRx 5G mm-wave phased arrays. The proposed antenna design shown in Figure 16b has a 10-dB reflection coefficient of 0.5 GHz. The peak array gain is 18 dBi and 12 dBi for the Tx and Rx ends, respectively. The measured EIRP (Effective Isotropic Radiated Power) at 29 GHz is 24.5 dBm. The photograph of the flip-chip test board with 2 \(\times\) 2 antenna elements is shown in Figure 20b. Based on the proposed beamformer packaged module, a 32-element (4 \(\times\) 8) TRX array with PCB integrated microstrip antennas on a four-layer PCB stack was proposed in [60]. The angular beam-scanning of \(\pm\)50\({}^{\circ}\) in the azimuth and \(\pm\)25\({}^{\circ}\) in the elevation plane was achieved, as shown in Figure 20c. In [67], a multilayer 64-element dual-polarized antenna-in-package assembly with four-SiGe BiCMOS multi-chip phased array operating at 28 GHz was proposed for 5G mm-wave communication. The proposed module has four mounted SiGe BiCMOS transceiver ICs supporting dual polarization in Tx and Rx modes. The proposed antenna array has a 3-GHz bandwidth at an operating frequency of 28 GHz. The measured Tx gain is around 35 dBi for the 64-element antenna array. The angular beam-scanning of \(\pm\)40\({}^{\circ}\) in the azimuth and elevation plane was achieved, as shown in Figure 21c. Figure 20: (a) Block diagram of 2 \(\times\) 2 transmit/receive 5G phased array. (b) Photograph of the flip-chip test board with 2 \(\times\) 2 transmit/receive 5G phased array. (c) Measured E and H-plane patterns of 4 \(\times\) 8 transmit/receive 5G phased array in Rx mode (Redrawn from [54; 60]). Table 2 shows the performance of recently developed phased arrays for 5G access terminals demonstrated in this section. A performance comparison was made based on the beam-scanning capability and array elements of various phased arrays. Figure 21: (**a**) Overview of antenna array assembly with transceiver ICs. (**b**) Photograph of the assembled antenna array package with four transceiver ICs. (**c**) 64-element TX phased-array angular beam-scanning of \(\pm 40^{\circ}\) (Redrawn from [67]).