Common-mode level shift treatment circuit and method for operational amplifier

Abstract

The embodiment of the invention discloses common-mode level shift treatment circuit and method for an operational amplifier. The treatment circuit comprises a buffer for buffering a received signal so as to improve the driving capacity of the signal, a first filter circuit for performing band-pass filtering for the signal processed by the buffer, a first operational amplifier for amplifying the signal processed by the buffer and subjected to band-pass filtering, and a second filter circuit for performing band-pass filtering for the signal amplified by the signal amplifier so as to obtain a filtered signal. By adopting the treatment circuit, the problem of common-mode level shift at the input end and the output end of the operational amplifier during amplifying a signal transmitted through an RF antenna by a wireless manner through the operational amplifier can be solved; the output signals can be kept in the same common-mode level, which facilitates the subsequent treatment on digital signals, and moreover, signal error code can be avoided.

Description

technical field [0001] The present invention relates to the technical field of radio frequency identification (Radio Frequency Identification, RFID), in particular to a processing circuit and method for common-mode level offset of operational amplifiers. Background technique [0002] Radio frequency identification technology is a non-contact automatic identification technology, which transmits signals through electromagnetic waves or inductive coupling to complete automatic identification of target objects. Compared with other automatic identification technologies such as barcodes, magnetic cards, and contact IC cards, RFID technology has the advantages of no manual intervention in the identification process, multiple targets can be identified at the same time, a large amount of information storage, and it can work in various harsh environments. Therefore, RFID technology has been widely used in fixed asset management, production line automation, animal and vehicle identific...

AI Technical Summary

Problems solved by technology

[0004] Since the information transmission between the reader and the card is wirelessly transmitted through the radio frequency antenna, the signal is relatively weak, and an operational amplifier is needed to amplify it. However, due to layout asymmetry and process deviation during the amplification process of the operational amplifier, the current is asymmetrical. , it will lead to the offset of the common mode level of the input terminal and output terminal of the operational amplifier, and in severe cases, the signal demodulation will not come out, resulting in the failure of card search and so on.

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