| 摘要 |
An embodiment of the present invention improves the efficiency of radio frequency identification (RFID) systems and helps to extend the effective read range for certain configurations of closely spaced RFID tags. Specifically, an embodiment helps to minimize energy losses that result when there is excess energy from the excitation source. This excess energy has the potential to damage the circuitry in RFID tags. A shunt regulator is often used to protect the RFID circuitry by clamping the voltage, but has the undesirable effect of converting this excess excitation energy into heat. Various embodiments are directed toward using only as much of the excitation energy as necessary to power the RFID circuitry. These embodiments include circuitry for a constant current power supply that can be implemented either with discrete components or built into a new ASIC design; a network that minimizes the amount of energy that is converted to heat by the shunt regulator built into many RFID circuits; and/or a sleep mode for reducing the energy consumed by an RFID tag after it has been read. An embodiment may have the benefit of making more of the excitation energy available to power other RFID tags nearby-thereby improving system performance and read range.
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