A low-power receiver for long-distance backscatter communication system
A technology for backscattering and communication systems, applied in transmission systems, multi-frequency code systems, digital transmission systems, etc., and can solve problems such as low power, low sensitivity, and inapplicability
Active Publication Date: 2021-06-04
FUDAN UNIV +1
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Problems solved by technology
The demodulation method of this kind of receiver belongs to non-coherent demodulation. Because the passive diode has the characteristic of turning on voltage, the envelope detector 320 will not work normally under low input power, so this kind of demodulation method has low sensitivity.
In long-distance backscatter communication, the power of the signal sent by the base station is already very low when it reaches the receiver after long-distance attenuation, so this kind of receiver is not suitable for long-distance backscatter communication system
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[0016] Specific embodiments of the present invention will be further described below.
[0017] Such as figure 1 As shown, the radio frequency input port 110 of the receiver receives the multi-carrier modulation signal sent by the base station. Suppose the reference carrier is located at ω c,1 , its expression is: x 1 (t)=V in,1 · sin(ω c,1 t). The expression of the modulating signal is: x 2 (t)=m(t)·V in,2 · sin(ω c,2 t), and its carrier frequency is ω c,2 , where m(t) is the modulation information. The output DC voltage of the envelope detector 130 has a square relationship with the voltage amplitude of the input radio frequency signal, and its expression is: y=k x 2 This dual-carrier signal is passed through the envelope detector to obtain the output expression:
[0018]
[0019] where 2·V in,1 ·V in,2 m(t) sin(ω c,1 t)sin(ω c,2 t) This item contains the known intermediate frequency ω c,1 -ω c,2 signal of. The frequency of the local oscillator signal 14...
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The invention belongs to the technical field of backscatter communication, in particular to a low-power receiver used in a long-distance backscatter communication system. The receiver of the present invention mainly includes circuit modules such as a radio frequency front end, an analog-to-digital converter, a digital baseband, and a memory. The receiver adopts multi-carrier modulation, and the radio frequency front-end circuit utilizes the square term in the transfer function of the envelope detector to extract the frequency difference between carriers to obtain a definite intermediate frequency signal. And coherent demodulation is performed on the intermediate frequency signal, so that higher receiving sensitivity can be realized. In addition, unlike the coherent demodulation method of traditional active receivers, the receiver chip does not require high-frequency local oscillator signals, so it can save a lot of power consumption. The receiver can be applied to a backscatter communication system, can effectively improve the communication distance, and at the same time meet the requirements of the backscatter communication protocol for low power consumption of the receiver.
Description
technical field [0001] The invention belongs to the technical field of backscatter communication, and in particular relates to a receiver chip applied to a long-distance backscatter communication system. Background technique [0002] The rapid development of the Internet of Things technology has greatly changed people's lives, and along with the Internet of Things technology, Radio Frequency Identification technology (Radio Frequency Identification) has a broader application scenario. Generally, according to the communication frequency between the reader and the tag, the radio frequency identification system can be divided into low frequency (LF: low frequency), high frequency (HF: high frequency), ultra high frequency (UHF: ultra high frequency) several Large category, in which low-frequency and high-frequency RFID systems use electromagnetic coupling communication. The UHF RFID system uses electromagnetic wave emission and electromagnetic wave backscattering. The backsca...
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IPC IPC(8): H04B1/16H04L27/26
CPCH04B1/16H04L27/2647
Inventor 张轶超闫娜闵昊
Owner FUDAN UNIV