Rfid reader and circuit and method for echo cancellation thereof

Abstract

An echo cancellation circuit for an RFID reader and the method thereof are provided. The echo cancellation circuit includes a gain calculator, a gain adjustment circuit, and a subtraction circuit. The gain calculator provides a complex gain value according to a carrier signal and a received signal through an adaptive algorithm. The gain adjustment circuit is coupled to the gain calculator. The gain adjustment circuit multiplies the carrier signal by the complex gain value, and outputs the result of the multiplication. The subtraction circuit is coupled to the gain adjustment circuit. The subtraction circuit subtracts the output of the gain adjustment circuit from the received signal, and then provides the result of the subtraction as the output signal of the echo cancellation circuit.

Description

technical field [0001] The present invention relates to a radio frequency identification device (RFID: radio frequency identification) reader, and in particular to an echo cancellation circuit and method for the radio frequency identification device reader. Background technique [0002] FIG. 1 shows a schematic diagram of a conventional RFID reader 101 and several RFID tags, such as three RFID tags 102-104. The reader 101 emits ultra high frequency (UHF: ultra high frequency) electromagnetic waves to drive the tags 102 - 104 so that the tags 102 - 104 can return data to the reader 101 . FIG. 2 shows a schematic diagram of the circuit of a conventional radio frequency identification device reader 101 . The radio frequency identification device reader 101 includes a radio frequency oscillator (RF oscillator) 201, a power splitter (power splitter) 202, a power amplifier (PA: power amplifier) ​​203, a modulator (modulator) 204, a circulator (circulator) 205, An antenna 206 , a...

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