Muting circuit for analog filters in radio frequency identification (rfid) systems
AssigneeAvid Identification Systems, Inc.
InventorsMark Blair, Martin S. H. Ma
Life of this patent
Estimating the term…
Abstract
An apparatus, which allows a radio frequency identification (RFID) reader to recover quickly from transient input to its receiving subsystem when transitioning from writing to an RFID transponder to reading its response. In particular, this apparatus is comprised of muting circuits, which both attenuate transients in its receiving subsystem while writing to a transponder, and help the receiving subsystem settle quickly after experiencing such transients.
Claims18
1-23. (canceled)
A method for communicating with a radio frequency identification (RFID) transponder using a RFID reader, the RFID reader comprising a detector circuit, a plurality of active filter stages, and a detector-muting switch arranged between the detector circuit and the active filter stages, the method comprising:
- transmitting a command signal from an RFID reader to the RFID transponder, the transmitting being performed while the detector-muting switch is closed to mute a signal from the detector circuit to the active filter stages;
- after transmitting the command signal, opening the detector-muting switch;
- detecting, with the detector circuit while the detector-muting switch is open, a response signal transmitted by the RFID transponder in response to the command signal;
- filtering the detected response signal using the active filter stages;
- and
- demodulating, at the RFID reader, the filtered response signal to provide digital data received from the RFID transponder transmitted in the response signal.
Circuitry for communicating with a radio frequency identification (RFID) transponder, the circuitry comprising:
- an antenna circuit;
- and
- a receiving subsystem coupled with the antenna circuit, wherein the receiving subsystem comprises:
- a detector circuit configured to detect voltages present in the antenna circuit,
- a plurality of active filter stages, the active filter stages configured to output variations of the detected voltages that are caused by transmissions from the RFID transponder,
- a microcontroller configured to demodulate the output variations as digital data received from the RFID transponder, and
- a detector-muting switch between the detector circuit and the active filter stages to decouple the active filter stages from the detector circuit when the detector-muting switch is closed, and couple the active filter stages with the detector circuit when the detector-muting switch is open,
- wherein the microcontroller is configured to
- maintain the detector-muting switch closed during transmission of a command signal from the circuitry,
- open the detector-muting switch after the end of the transmission of the command signal.
Dependencies are inferred from the claim text.