60-GHz 64- and 256-Elements Wafer-Scale Phased-Array Transmitters Using Full-Reticle and Subreticle Stitching Techniques

This paper presents 60-GHz wafer-scale transmit phased arrays with 64- and 256-elements spaced λ/2 apart in the x- and y-directions, and occupying an area of 21.4 × 22 mm² (471 mm²) and 41.4 × 42 mm² (1740 mm²), respectively. The 64-element phased array is built as a complete reticle and includes 64 independent transmit channels with 5-b phase control, 3-b (9 dB) amplitude control, a saturated output power of 3 dBm at the antenna port, a 1-64 distribution network with redundant line amplifiers, and a high-efficiency on-chip antenna at each element. In addition, redundant serial digital interface and power strips, dual series metal-insulator-metal capacitors, and multiple RF inputs are employed for improved yield. The 256-element array uses the same phased-array blocks as the 64-element design, but is built using a subreticle stitching technique so as to result in a chip which is larger than the standard reticle size (22 × 22 mm²). The 64and 256-element arrays result in a half-power beamwidth of 12° and 6° in the E- and H-planes, a directivity of 23 and 29 dB, respectively, and scan to ±55° in the E- and H-planes with near-ideal patterns and a crosspolarization level of lesser than -30 dB. The measured equivalent isotropically radiated power (EIRP) of the 64-element array is 38 dBm at 62 GHz with a 3-dB bandwidth of 61-63 GHz, while that of the 256-element array is 45 dBm at 61 GHz with a 3-dB beamwidth of 58-64 GHz. A 1-4-Gb/s communication system is also demonstrated using the 64-element phased array up to ±45° scan angles, and at 4-, 30-, and 100-m ranges. To the best of our knowledge, this paper represents the first demonstration of large size (64and 256-element) phased-array transmitters on a single wafer.