CMOS UHF RFID Rectifier Design and Matching: an Analysis of Process and Temperature Variations

Radio Frequency (RF) power transfer is an enabling technology of RFID systems. CMOS RF rectifiers enable miniaturization and improved integration with full systems. For certain applications, rectifiers may need to be deployed in high or low temperature environments, which can affect their power conversion efficiency (PCE). This work presents the design of a high efficiency 915 MHz CMOS Dickson charge-pump in a 28 nm FD-SOI process, and investigates antenna-based impedance matching as a method of maximizing the PCE for different temperatures and CMOS process variations. With a co-designed antenna, the proposed rectifier achieves 5.4x higher PCE compared to simple inductive-matching at -20 dBm. The PCE is then analyzed for CMOS process and temperature variations. It is shown that the rectifier can maintain 94% of its peak PCE at -15 dBm at -10°C through input-impedance matching. The proposed rectifier and matching technique achieves the highest PCE compared to state-of-the-art Dickson multipliers, while having the smallest die area.