US Patent 10116353 Contactless communication device and electronic system having the same

A contactless communication device includes a transceiver and a contactless communication chip. The transceiver generates an antenna voltage based on an electromagnetic wave received from an external device. The contactless communication chip generates an internal clock signal, operates based on the internal clock signal, and communicates with the external device using the transceiver. The contactless communication chip generates a reference clock signal based on the antenna voltage and adjusts a frequency of the internal clock signal based on the reference clock signal.