E-Band 2×2 Unit Phased Array with Die-to-Die Stitching Scalability for Wafer-Scale Phased Array Systems

This paper presents an E-band 2×2 unit phased array with stitching scalability from die-to-die up to reticle-to-reticle for wafer-scale phased-array systems, implemented in 28-nm CMOS technology. The 2×2 unit array includes RF beamforming transmit-receive (TRX) channels with 4-bit phase control and 4-bit gain control, folded dipole antennas spaced λo/2 apart in both azimuth and elevation directions, and a signal distribution network. To enable die-to-die stitching scalability, the distribution network incorporates a forward-and-divider (FD) switch and a hybrid coupler. The unit array achieves a TX peak gain of 20 dB with a 3-dB bandwidth from 80 to 86.5 GHz, and RX peak gain of 11 dB with a 3-dB bandwidth from 83 to 87.3 GHz at the broadside beam. The measured peak EIRP at P1dB is 7.4 dBm, which can be scaled to 31 dBm for 8×8 array.