Circuit for generating clock signal and decoding data signal for use in contactless integrated circuit card

摘要

An integrated circuit card which includes a circuit for generating a clock signal and for restoring data. The circuit includes a receiver for receiving a radio frequency signal having a pause period; a divider for dividing the received signal; a first counter for counting a period of the divided signal at each non-pause period of the received signal; a second counter for counting a period of the divided signal; and a decoder for generating a synchronous clock signal and a decoded data signal in response to outputs of the first and second counters. The second counter is reset by the synchronous clock signal. The circuit is capable of generating a synchronous clock signal and decoding a received data signal so as to be compatible with ISO/IEC 14443 Type A protocol, based on the received radio frequency signal that is transferred from a card reader. The circuit provides an exact decoding result even when the pause period of the radio frequency received from the card reader varies over a predetermined range.