Comparison of Energy Harvesting via Modulation Schemes for Passive Sensor RFID

In this paper we describe different ways to transmit power more efficient to a passive radio frequency identification (RFID) sensor transponder. For a realistic approach at 5.8 GHz we made an inquire on standards and regulations in Europe, especially Germany, and United States of America. Based on this and various publications we designed a realistic link budget. We describe and present a method using modulated signals sent to the transponder and the gain on increasing the power rectified compared to a continuous wave (CW) signal. The used modulations are on-off-keying (OOK), binary phase shift keying (BPSK), quaternary phase shift keying (QPSK) and differential quaternary phase shift keying (DQPSK). For verification and comparison the measurements were conducted on two single stage voltage doublers (Greinacher circuit). Used diodes are PCC110 and HSMS-2862 from Powercast and Avago, respectively. The power gain reaches values as high as 5.8 dB at an input power of -9.3dBm for an OOK modulated reader signal.