Patent ID: 8285242

Claim:
A radio frequency integrated circuit for use with an RFID tag for use on a commodity, comprising: an antenna for communicating data by use of radio waves, including detecting a radio signal of a first frequency and detecting a radio signal of a second frequency; and an IC module for processing and storing data, wherein the IC module comprises: a plurality of memories; a read-write unit for performing processes of reading the data from, and writing data into, a target memory of the plurality of memories; and a selector for receiving an electric signal outputted from the antenna having received a radio signal, and for specifying a first memory of the plurality of memories as a target memory for reading the first target memory in response to detection of said radio signal of said first frequency and for restricting against reading the second memory in response to detection of said radio signal of said first frequency, and for specifying a second memory of the plurality of memories as a target memory for reading the second target memory in response to detection of said radio signal of said second frequency, wherein the plurality of memories and the read-write unit are in the RFID tag, wherein the first frequency is in the MHz range and the second frequency is higher than the first frequency and is in the UHF range, wherein the read-write unit performs both read and write processes in said first memory as a specified target memory in response to said first frequency of a radio signal, wherein the read-write unit performs both read and write processes in said second memory as a specified target memory for shared memory in response to said first frequency of a radio signal, wherein the read-write unit performs only read processes in said second memory as a specified target memory in response to said second frequency of a radio signal and wherein the second memory contains information for the commodity including information adapted for theft prevention of the commodity and wherein the first memory contains information on the commodity which is more detailed than the information in the second memory; the radio frequency integrated circuit further comprising: a PLL circuit adapted to receive the electric signal outputted from the antenna, and generate and output an operating clock based on the outputted electric signal; and a PLL setting unit adapted to receive one of the electric signal outputted from the antenna and an output signal of the PLL circuit, and dynamically set the PLL circuit based on the one of the electric signal and the output signal so that the PLL circuit generates the operating clock having a fixed frequency, wherein the read-write unit operates according to the operating clock which has the fixed frequency and which is outputted from the PLL circuit.