Demodulation circuit used in a passive ultrahigh frequency radio-frequency identification label chip

Abstract

The invention discloses a demodulation circuit used in a passive ultrahigh frequency radio-frequency identification label chip, and the circuit comprises an envelope detection circuit, a voltage limiting circuit, a low-pass filter circuit, a reference level generation and comparison output circuit. All are in series connection in the order as they are listed aforementioned. The envelope detection circuit of the invention adopts the method of active envelope detection to restore a baseband signal modulated on a high-frequency carrier wave, and the restored envelope signal is limited to the common-mode input range of the latter-stage circuit through the voltage limiting circuit, and then through the low-pass filter circuit, noise signals in the filter high-frequency carrier wave and the environment are filtered before being transmitted to the reference level generation and comparison output circuit where they are compared to the reference level. Following that, digital signals are outputted for digital baseband processing. With high sensitivity yet low power consumption, the circuit is also small in size.

Description

technical field [0001] The invention relates to the field of analog integrated circuits, in particular to a demodulation circuit applied to passive ultra-high frequency radio frequency identification tag chips. Background technique [0002] As an automatic identification technology, radio frequency identification (RFID) has the advantages of fast reading speed, long life, reusable, small size, large data storage capacity and less affected by the external environment compared with traditional barcodes, especially Passive UHF RFID has the characteristics of long identification distance. This technology is widely used in logistics warehouse management, manufacturing, retail, postal express and other service and production fields. [0003] Usually the basic RFID system is mainly composed of RFID tags, readers, antennas, middleware and application software. As the real carrier of data, RFID tags are composed of tag chips and antennas. The tag chip is mainly composed of RF analo...

AI Technical Summary

Problems solved by technology

Demodulation circuits are usually divided into voltage-type and current-type; current-type demodulation circuits usually convert voltage signals into current signals for processing, and their structures are often complex

The voltage-type demodulation circuit has a simple structure and is easy to implement, but the traditional voltage-type demodulation circuit uses Schottky diodes as the envelope detection circuit, which will bring relatively high costs in the standard CMOS process

The method of using internal and external threshold compensation will increase additional chip area and power consumption

In addition, the reference level generation circuit in the demodulator adopts the method of resistive voltage division, which will bring a relatively large area

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