High Data-Rate Communication in Near-Field RFID and Wireless Power Using Higher Order Modulation

We present the theory of high-order modulation for near-field RF identification (RFID) and wireless power transfer (WPT) systems. We show that while related, the design of RFID and WPT systems differ. The theory and calculation of load modulated quadrature amplitude modulation (QAM) and phase shift keying (PSK) is presented. We then present two experimental prototypes. The first demonstrates a 16-QAM RFID link achieving > 480 kb/s at a 2.38-MHz carrier (> 19.8 fractional bandwidth), significantly higher than the < 1 fractional bandwidth of traditional RFID systems. The second experimental prototype demonstrates 4-PSK for WPT applications achieving a data rate > 256 kb/s at a 2.38-MHz carrier (a 10.7% fractional bandwidth) with an average efficiency reduction of only 4%.