Passive Tag

As a first constraint, recall that all passive tags require that power be derived from the incident carrier frequency broadcast by the reader. For low-cost applications, this will likely be in the high frequency (HF) or UHF bands, as discussed previously. Given the performance limitations of organic materials, it is highly unlikely that harvesting of UHF frequencies will be possible. As a result, the circuit analysis here will focus exclusively on HF tags. 

RFID tags can be divided into three types passive, active, and semi-passive. A passive tag... 

Keywords Radio-frequency identification, RFID, passive tag, temperature sensor, gas sensor, ASK, low power, system-on-chip, energy recovery. 

Lee, J-W et al. A Fully Integrated EPC Gen-2 UHF-Band Passive Tag IC Using an Efficient Power Management Technique, IEEE trans. Circuit and Systems, vol. 61, no. 6, pp. 2922-2932,2014. 

On the other hand, passive - or battery assisted passive (BAP) - RFID tags are provided with very low cost batteries (cost 5) or completely inactive (up to 40 Eurocents). The difference is the impossibility of activating the reading/receiving system (distance up to 10 cm frequency 1 Hz, resolution 100 pm). This apparent limitation is the key of the success of RFID passive tags (Figure 12.2). Other advantages are ... 

RFID tags can be classified using three schemes. First, the tags can be classified based on their ability to perform radio communication—active, semi-active (semi-passive), and passive tags. Second, the tags can be classified based upon their memory—read-only, read-write or write-once, and read-many. Finally, the tags can also be classified based on the frequency in which they operate—LF, HF or UHF. 

Passive tags completely rely on the energy provided by the reader s magnetic field to transmit the radio signal to and from the reader. It does not have a battery. As a result, the read range varies depending upon the reader used (Lyngsoe, n.d.). A maximum... 

Unlike passive tags, active RFID tags contain a battery to power the circuitry, and generate and transmit radio signals to the reader. Onboard power supply can enable long-distance communi-... 

The cost of the passive tags depends upon the frequency. Normally the LF tags are more expensive than HF or UHF because of the size of the antennae (RMOROZ, 2004). It normally costs more than 2 and goes as high as 10. The HF tags are cheaper than the LF tags and normally cost less than a dollar. 

Radio frequency identification (RFID) is growing rapidly in multiple end use segments such as transportation, security, and asset/inventory management. Polymer blends can be used in the housings, internals, and plastic films containing passive tags. 

RFID is an automatic identification method using devices called RFID tags or transponders. An RFID tag is an object that can be attached to or incorporated into a product, animal, or person for the purpose of identification using radio waves. Chip-based RFID tags contain silicon chips and antennas. Passive tags require no internal power source, whereas active tags require a power source. 

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