The IC has a logic unit that makes decisions and provides memory to store
data. Actually, the IC is a small microprocessor, and the latest ones have 40,000
to 50,000 transistors,more than the original IBM PC. The IC needs power to operate.
This power may come froma battery on the tag (in an active tag) or it may
be obtained from the radio energy radiated by the interrogator antenna (in a
passive tag). A part of the IC is dedicated to controlling power