| 摘要 |
A system and method is provided for using a frequency division circuit to produce a desired frequency in a radio frequency identification transponder (RFID tag). In a preferred embodiment of the present invention, an RFID tag includes a frequency division circuit connected to a logic circuit and a oscillator. The logic circuit is adapted to identify at least one frequency associated with a received RF signal (e.g., the frequency of the signal, a frequency identified by the signal, etc.). This frequency is then used by the frequency division circuit to calibrate the frequency provided by the oscillator. In one embodiment of the present invention, the frequency division circuit includes at least one variable counter adapted to divide the frequency provided by the oscillator (i.e., the oscillation frequency) by a programmable factor to produce a desired frequency. The desired frequency is then provided to the logic circuit and used to modulate a received RF signal. In another embodiment of the present invention, the frequency division circuit further includes at least one fixed counter, wherein the fixed counter is not programmable. In this embodiment, the fixed counter is used to produce a particular (lower) frequency, and the variable counter is used to produce the desired frequency. Such an embodiment, for example, can be used to decrease the amount of time required to produce a desired frequency (e.g., by starting with a lower fixed frequency) and increase the amount of time available to perform alternate functions (e.g., communicate with external devices, etc.).
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