Electronics and Telecommunications Research Institute

Sang Gee Kang

Jong-Suk Chae

Jong Suk Chae

Jae Ick Choi

Ji-Hoon Bae

Gil Young Choi

Chan-Won Park

Heon Jin Hong

Donghan Lee

Kwang-Soo Cho

Man Sik Park

Cheng-Hao Quan

Ung Hee Park

Ki Suk Yoo

Provided are an RFID reader and a method for suppressing transmission leakage signals thereof. The RFID reader includes a first loop, a second loop, and a digital signal processor. The first loop suppresses a first transmission leakage signal of an RX signal in response to a first leakage control signal. The second loop suppresses a second transmission leakage signal of the RX signal, received through the first loop, in response to a second leakage control signal. The digital signal processor generates the first leakage control signal and the second leakage control signal. The digital signal processor generates the first leakage control signal until the level of the first transmission leakage signal becomes equal to or lower than the level of a first reference transmission leakage signal.

RFID reader and method for suppressing transmission leakage signal thereof

An intermodulation signal detector is implemented in a non-linear super high frequency circuit for stably detecting an intermodulation signal regardless of the variations of non-linear characteristics of the super high frequency element and an external environment by using combined two transmission lines on which signals have the same amplitude and 180&deg; different phases.

Intermodulation signal detector

Provided with an optimal control method for an adaptive feedforward linear amplifier that includes an adaptive controller connected to first and second PLLs (Phase Locked Loops) respectively determining frequency bands for a main signal component and a distortion signal component. The adaptive controller adaptively controls control voltages of a first variable phase shifter and a first variable attenuator constituting a main signal cancellation loop and control voltages of a second variable phase shifter and a second variable attenuator constituting an error signal cancellation loop. The optimal control method includes the steps of: (a) after initialization of necessary parameters, reading a strength of an input signal, determining the initial optimal control voltages of the first and second variable phase shifters and the first and second variable attenuators, outputting the corresponding control voltages, and setting the first PLL to read a main signal strength of the main signal cancellation loop; (b) controlling the optimal control voltages of the first variable phase shifter and the first variable attenuator until the main signal strength becomes lower than a first threshold, if the main signal strength exceeds the first threshold; (c) determining the main signal strength read out from the error signal cancellation loop, if the main signal strength is greater than the first threshold, repeat step (b), otherwise; and (d) controlling the optimal control voltages for the second variable phase shifter and the second variable attenuator until the difference between the main signal strength and the distortion signal strength becomes lower than a second threshold, if the difference is greater than the second threshold.

Optimal control method for adaptive feedforward linear amplifier

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Taejon, South Korea

Sang Gee Kang