A Compact 60-GHz Wireless Power Transfer System

The first reported full-system 60-GHz wireless power transfer (WPT) solution that can power batteryless and charge coil-free compact WPT devices is presented. The system is fabricated in a 40-nm digital CMOS process and an inexpensive packaging material. In the rectenna (RX), a grid antenna is integrated with a complementary cross-coupled oscillator-like rectifier. At a 4-cm spacing from the transmitter (TX), the RX harvests energy at a rate of 1.22 mW with a 32.8% efficiency, which is significantly higher than the prior state of the art. A novel theoretical analysis of the rectifier operation is presented that formulates all key specifications. The TX is equipped with a quad-core PA that produces a saturated output power (P
_sat
) of 24.6 dBm, which is the highest power delivery in digital CMOS at millimeter-wave bands. The TX peak power-added efficiency is 9.4%. In the TX, a 4 × 8-way differential power combining and a binary-tree architecture are implemented. The designed 2 × 2 grid array antenna helps the TX produce 35.3-dBm peak equivalent isotropically radiated power. The results of the performance characterizations of the full-system and all individually fabricated blocks are reported. The quadcore PA supports power control and beam steering. A four-port TX antenna is designed that shows a 70° steering range in simulations.