Active tag and radio frequency front-end chip thereof

Abstract

The invention discloses an active tag and a radio frequency front-end chip thereof. The chip comprises a non contact card interface circuit module, a clock induction shaping circuit module, a main carrier generation circuit module which is used for receiving induction clock output by the clock induction shaping circuit module, and carrying out phase locking and frequency dividing on the induction clock to output a modulation main carrier, a coding circuit module which is used for coding and outputting data output by the non contact card interface circuit module, and a transmitting circuit module which is used for using the received modulation main carrier to carry out switch keying modulation on the received coded data, wherein the frequency difference between the modulation main carrier and the induction clock is equal to the frequency of a subcarrier. According to the technical scheme of the invention, the load modulation depth equivalent to a modulation signal transmitted by the active tag front-end chip is nothing to do with the phase difference between the modulation main carrier and a reader main carrier, thus the shortcoming that the quality of the modulation signal is obviously decreased with the phase offset of the modulation main carrier is overcome.

Description

technical field [0001] The invention relates to communication technology, in particular to an active label and its radio frequency front-end chip. Background technique [0002] With the development of wireless communication technology and society, the identification system based on radio frequency identification RFID (Radio Frequency IDentification) technology (hereinafter referred to as RFID system) has been widely used in library management, access control management, food safety traceability, logistics management and In many fields such as mobile payment. [0003] In the RFID system, a passive tag Passivetag and a reader can be included; or an RFID system can also include an active tag ActiveTag and a reader. [0004] The circuit block diagram in the internal structure of the existing active tag is as follows Figure 1a As shown, it generally includes: an active tag radio frequency front-end chip 101 and a contactless tag (Contectless tag) 102; [0005] Wherein, the cir...

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Problems solved by technology

[0039] However, when the phase of the main carrier output by the main carrier generating circuit module 112 is neither consistent nor opposite to the phase of the main carrier of the magnetic field output by the reader, that is, when Φ≠Nπ, the V obtained according to formula 6 or formula 7 del The absolute values ​​of (t) are all reduced, resulting in the deterioration of the quality of the data sent by the active tag to the reader using ASK or PSK modulation; the deterioration of the data quality can be so severe that the reader cannot recognize the data sent by the active tag , for example, when the phase of the main carrier output by the main carrier generation circuit module 112 is orthogonal to the phase of the main carrier of the magnetic field output by the reader, that is, when Φ=(2N+1)π / 2, it can be obtained according to formula 6 or formula 7 V del The absolute values ​​of (t) are all 0, causing the reader to be unable to distinguish whether the data parsed from the envelope signal is 1 or 0

[0040] To sum up, the existing RFID system using ASK or PSK modulation is likely to cause the active tag to send a signal to the reader due to the phase difference between the main carrier output by the active tag and the main carrier output by the reader. The quality of the signal is significantly reduced, which reduces the stability and reliability of the communication between the active tag and the reader

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