Passive type RFID semiconductor device, IC tag, and control method
View Patent ↗To provide a semiconductor device capable of securely executing a reading operation to improve a reliability of read data, an IC tag including the semiconductor device, and a control method for the IC tag. A semiconductor device according to an embodiment of the present invention includes: a power supply voltage generating circuit for generating a power supply voltage based on a received radio signal; a power supply voltage generating circuit for detecting the power supply voltage; a memory area for storing predetermined data; a reading/writing circuit using different operation voltages for reading data from the memory area and writing data to the memory area; and a control circuit for executing a data reading operation for the memory area based on a detected power supply voltage.
1. A passive type radio frequency identification (RFID) semiconductor device that communicates with a reader/writer by using a radio signal, the passive type RFID semiconductor device comprising:
a power supply voltage generator that is responsive to a radio signal to generate a power supply voltage therefrom;
a storage unit that stores predetermined data;
a voltage detector that monitors a voltage level of the power supply voltage generated by the power supply voltage generator,
a control unit that can execute a read command included in the radio signal to generate a read signal and transmission data, if the voltage level of the power supply voltage is at least a first voltage value;
a memory access unit that is coupled to the storage unit and that can read the predetermined data from the storage unit in response to the read signal, if the voltage level of the power supply voltage is at least a second voltage value; and
a transmitter that is coupled to the control unit and that outputs the transmission data,
wherein the second voltage value is larger than the first voltage value, and
wherein the transmitter does not output the transmission data when the voltage level of the power supply voltage monitored by the voltage detector is at least the first voltage value but less than the second voltage value.
2. The passive type RFID semiconductor device according to claim 1 , wherein the control unit does not generate the read signal when the voltage level of the power supply voltage monitored by the voltage detector is at least the first voltage value but less than the second voltage value.
3. The passive type RFID semiconductor device according to claim 2 , wherein the control unit generates the read signal when the voltage level of the power supply voltage monitored by the voltage detector is at least the second voltage value, if the read command is present in the radio signal.
4. The passive type RFID semiconductor device according to claim 1 , wherein the control unit does not generate the transmission data when the voltage level of the power supply voltage monitored by the voltage detector is at least the first voltage value but less than the second voltage value.
5. The passive type RFID semiconductor device according to claim 4 , wherein the control unit generates the transmission data when the voltage level of the power supply voltage monitored by the voltage detector is larger than the second voltage value, if the read command is present in the radio signal.
6. The passive type RFID semiconductor device according to claim 1 ,
wherein the voltage detector generates a detection information of when the voltage level of the power supply voltage is at least the second voltage value, and
wherein the control unit comprises a memory that is coupled to the voltage detector and that stores the detection information.
7. The passive type RFID semiconductor device according to claim 6 , wherein the control unit comprises a memory that is coupled to the nonvolatile memory and that stores a tag ID outputted from the nonvolatile memory.
8. The passive type RFID semiconductor device according to claim 1 ,
wherein the voltage detector generates a detection information of when the voltage level of the power supply voltage is at least the first voltage value but less than the second voltage value, and
wherein the control unit comprises a memory that is coupled to the voltage detector and that stores the detection information.
9. The passive type RFID semiconductor device according to claim 8 , wherein the transmitter outputs the detection information stored in the memory when the voltage level of the power supply voltage is at least the first voltage value but less than the second voltage level.
10. The passive type RFID semiconductor device according to claim 1 , wherein the storage unit comprises a nonvolatile memory.
11. The passive type RFID semiconductor device according to claim 1 , further comprising a receiver that is coupled to the control unit and that demodulates data included in the radio signal.
12. The passive type RFID semiconductor device according to claim 1 , wherein the transmitter outputs the transmission data when the voltage level of the power supply voltage monitored by the voltage detector is at least the second voltage value, if the read command is present in the radio signal.
13. The passive type RFID semiconductor device according to claim 1 , wherein the transmitter is operable only when the voltage level of the power supply voltage is at least the first voltage value.
14. An integrated circuit (IC) tag, comprising:
the passive type RFID semiconductor device according to claim 1 ; and
an antenna that is configured for transmitting a radio signal including the transmission data to the reader/writer and for receiving a radio signal including a command from the reader/writer.
15. The IC tag according to claim 14 , wherein the antenna is coupled to the power supply generator and the transmitter.
16. The IC tag according to claim 15 ,
wherein the passive type RFID semiconductor device further comprises a receiver that is coupled to the control unit and that demodulates data included in the radio signal, and
wherein the antenna is further coupled to the receiver.
17. The passive type RFID semiconductor device according to claim 1 , wherein
the first voltage level comprises a minimum voltage value at which a logic circuit can operate, and
the second voltage level comprises a minimum voltage value at which data can be read from the storage unit.
18. The passive type RFID semiconductor device according to claim 1 , wherein
the transmission data comprises data to be transmitted to the reader/writer in response to the read command.
19. A control method for an integrated circuit (IC) tag that communicates with a reader/writer by using a radio signal, the control method comprising:
receiving a read command included in the radio signal from the reader/writer;
generating a power supply voltage of at least a first voltage value, based on the radio signal;
executing the read command to generate a read signal and transmission data, if a voltage level of the power supply voltage is at least the first voltage value;
detecting whether the voltage level of the power supply voltage is less than a second voltage value;
reading a predetermined data from a storage unit of the IC tag in response to the read signal, if the voltage level of the power supply voltage is at least the second voltage value; and
outputting the transmission data,
wherein the second voltage value is larger than the first voltage value, and
wherein the transmission data is not outputted when the detected voltage level of the power supply voltage is at least the first voltage value but less than the second voltage value.
20. The control method according to claim 19 , wherein the read signal is not generated when the detected voltage level of the power supply voltage is at least the first voltage value but less than the second voltage value.
21. The control method according to claim 19 , wherein the transmission data is not generated when the detected voltage level of the power supply voltage is at least the first voltage value but less than the second voltage value.
22. The control method according to claim 19 , further comprising outputting a detection result of the detecting to the reader/writer.
23. A communication method for a communication between an integrated circuit (IC) tag and a reader/writer by using a radio signal, the communication method comprising:
in the reader/writer, transmitting a read command included in the radio signal; and
in the IC tag:
receiving the read command included in the radio signal;
generating a power supply voltage of at least a first voltage value, based on the received radio signal;
executing the read command to generate a read signal and transmission data, if a voltage level of the power supply voltage is at least the first voltage value;
detecting whether the voltage level of the power supply voltage is less than a second voltage value;
reading a predetermined data from a storage unit of the IC tag in response to the read signal, if the voltage level of the power supply voltage is at least the second voltage value; and
outputting the transmission data,
wherein the second voltage value is larger than the first voltage value, and
wherein the transmission data is not outputted when the detected voltage level of the power supply voltage is at least the first voltage value but less than the second voltage value.
24. The communication method according to claim 23 , further comprising:
in the reader/writer:
determining that a reading operation regarding the read command ends in failure, if the reader/writer does not receive the transmission data corresponding to the read command within a predetermined time period after the reader/writer outputs the read command included in the radio signal; and
adjusting a position of the reader/writer if the reading operation ends in failure.