Demodulation circuit used for passive ultrahigh frequency RFID label chip

Abstract

The invention discloses a demodulation circuit used for a passive ultrahigh frequency RFID label chip. The demodulation circuit comprises a rectifying circuit, an envelope extraction circuit, a low-pass filtering circuit, a mean value generating circuit, a comparator, a shaping circuit, an enabling control circuit and a biasing circuit. The rectifying circuit has a primary level and an auxiliary level, rectifying is achieved through threshold value compensation, and the envelope extraction circuit extracts envelopes under the control of the enabling control circuit. The low-pass filtering circuit is directly of an RC structure, and the mean value generating circuit is composed of an operational amplifier, a diode and a capacitor. Mean value generating is achieved based on a peak detection principle, the comparator achieves comparing through an open-loop operational amplifier, the shaping circuit is composed of two cascaded inverters, the mode that three inverters are cascaded is adopted for the enabling control circuit to control the mean value generating circuit, the comparator and the shaping circuit, so that power consumption needed when the demodulation circuit does not work is greatly lowered, and the biasing circuit provides nA-level currents for the rectifying circuit, the mean value generating circuit and the comparator. The demodulation circuit has the advantages of being high in sensitivity, large in input range, low in power consumption, small in area and low in cost.

Description

technical field [0001] The invention belongs to the technical field of radio frequency identification, and more specifically relates to a demodulation circuit for a passive ultra-high frequency RFID tag chip. Background technique [0002] With the continuous development of UHF RFID system technology, the market has higher and higher requirements for system performance. Long-distance communication, high reliability, low bit error rate, and low distortion increase the design difficulty. When the reader puts the modulated After the signal is sent to the tag, the tag receives the signal through the antenna and demodulates to obtain the baseband signal. Demodulation technology is currently divided into analog signal demodulation and digital signal demodulation, which is realized by changing the amplitude, frequency and phase of the carrier signal. The demodulation method can use synchronous detection method and envelope detection method. The principle of synchronous detection me...

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Problems solved by technology

[0004] In view of the defects of the prior art, the purpose of the present invention is to provide a demodulation circuit for passive UHF RFID tag chips, aiming at solving the problems of poor sensitivity of tag chips, low input range and high power consumption

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