AC-COUPLED RFID SYSTEM

摘要

An AC-coupled RFID system is disclosed. Embodiments of the invention statistically correlate the transmit data from a baseband transmit signal and the receive data in a receive signal after the signal has passed through a baseband receive filter. By using a receive bandpass or high-pass filter at baseband, the receiver can be AC-coupled in the baseband. This AC coupling significantly reduces cost and complexity by eliminating high-power reflected signals at and near DC. The high-pass corner frequency of the receive filter passes enough of the receive signal to still be measureable. The correlation is used to estimate the reflected carrier, which in turn enables cancellation of the carrier, improving RFID reader sensitivity.

主权项

1. A system for reading RFID tags, the system comprising:
a transmit path to produce a transmit signal; a receive path to demodulate a tag signal produced in response to the transmit signal; a baseband receive filter to AC-couple a signal in the receive path to produce an AC-coupled receive signal; and a carrier estimator connected to the receive path and the transmit path to estimate at least one of an amplitude and a phase of a reflected transmit signal based on the transmit signal and the AC-coupled receive signal.