RFID chips use radio signals to transmit data over short distances. They are used typically for security, tracking, and identification purposes. RFID chips can be paired with other circuitry to create tags or readers that also use radio frequency identification (RFID) technology.

RFID chips wirelessly transmit their unique serial-number identifiers, even when embedded in objects such as clothing or currency. When an RFID reader broadcasts a request for this information, the RFID tag that contains the corresponding ID code responds with a transmission. Some of these RFID devices do not have batteries, and are instead powered by the radio signals themselves.

This diagram shows the role of an RFID chip in a transponder.

Image Credit: RFID Handbook

Types of RFID Chips

The Engineering360 SpecSearch database categorizes RFID chips according to the type of device (passive, active, or semi-passive) in which the chips are used.

• Passive devices are RFID tags without batteries. They draw power from the magnetic field that is created when radio waves reach the chip's antenna. Using this generated power, passive RFID devices transmit information that is stored on the chip.
• Active devicesare RFID tags that use a battery to power the microchip's circuitry and transmit a signal to the reader. Active tags can be read from distances of 100 ft. or more.
• Semi-passivedevices are similar to active tags, but only use the battery to run the microchip's circuitry. To communicate with the reader, these tags draw power from the magnetic field that is created. Some semi-passive tags "sleep" until "awakened" by a signal from the reader.

Suppliers may also designate their products as encrypted or short-range.

Specifications

RFID chips may be equipped with a serial, wireless, TTL, or I2C interface. Frequency, memory, read rate, detection range and operation temperature are the key performance specifications to consider. When specifying the frequency, industrial buyers should note that products use low, high, ultra-high and microwave frequencies. Each has advantages and disadvantages, depending upon the user's application.

Features

Like other types of radio frequency identification (RFID) products, some chips can operate without physical contact between the tag and the reader. Portability, encryption, and continuous reporting are also important features to consider, depending upon the application.

Resources 

RFID Handbook

Infineon - Object Identification

Atmel - RF Identification