Passive RFID tags have no internal power supply. The minute electrical current induced in the antenna by the incoming radio frequency signal provides just enough power for the CMOS integrated circuit (IC) in the tag to power up and transmit a response. Most passive tags signal by backscattering the carrier signal from the reader. This means that the aerial (antenna) has to be designed to both collect power from the incoming signal and also to transmit the outbound backscatter signal. The response of a passive RFID tag is not just an ID number (GUID): tag chip can contain nonvolatile EEPROM (Electrically Erasable Programmable Read-Only Memory) for storing data. Lack of an onboard power supply means that the device can be quite small: commercially available products exist that can be embedded under the skin.
Semi-passive RFID tags are very similar to passive tags except for the addition of a small battery. This battery allows the tag IC to be constantly powered. This removes the need for the aerial to be designed to collect power from the incoming signal. Aerials can therefore be optimized for the backscattering signal. Semi-passive RFID tags are faster in response and therefore stronger in reading ratio compared to passive tags.
Unlike passive and semi-passive RFID tags, active RFID tags (also known as beacons) have their own internal power source which is used to power any ICs and generate the outgoing signal. They are often called beacons because they broadcast their own signal. They may have longer range and larger memories than passive tags, as well as the ability to store additional information sent by the transceiver. To economize power consumption, many beacon concepts operate at fixed intervals. At present, the smallest active tags are about the size of a coin. Many active tags have practical ranges of tens of meters, and a battery life of up to 10 years. The best part of the Active tag is that the microcontroller is very powerful and thus additional hardware can be interfaces with the tag to allow different kinds of data gathering.
|Active RFID tags have a battery, which is used to run the microchip’s circuitry and to broadcast a signal to a reader
(Note that Semi passive tag has battery as well but the battery is used to run the chip’s circuitry, but communicate by drawing power from the reader)
|Passive tags have no battery. Instead, they draw power from the reader, which sends out electromagnetic waves that induce a current in the tag’s antenna|
|TheRangeofActive Tagsare usually in the order of > 10 meters||Passive tags generally have very low read range|
|The Tag price is very costly compared with the Passive version||The Tag cost is very cheap, usually under 40 cents|
|Always needs battery power||No battery power is needed, ever|
|Cannot be disposed with the product packaging||Can be disposed with the product packaging|
|Can take care of some complex calculations, data logging and customized encryption algo||Can’t be so complex when it comes to processing due to power, size and complexity issues|