Low-noise amplifier with adjustable working frequency in UHF (ultra-high-frequency) RFID (Radio Frequency Identification) reader

Abstract

The invention relates to a low-noise amplifier with an adjustable working frequency in a UHF (ultra-high-frequency) RFID (Radio Frequency Identification) reader, improving linearity by adopting a second-order intermodulation current injection structure at an input terminal and realizing an adjustable central working frequency by adopting a switched capacitor structure at an output terminal. The second-order intermodulation current injection structure acquires an injection current value when a third-order intermodulation current value is zero by analyzing the nonlinearity characteristic of a MOS (Metal Oxide Semiconductor) tube; and a switched capacitor is formed by connecting the MOS tube and a capacitor at the output terminal. The capacitor is switched on when the MOS tube is conducted, and the capacitor is switched off when the MOS is cut off, i.e. the capacitor value is changed at the output terminal by conducting or cutting off the MOS. According to the known, when an inductor value L is unchanged, and a capacitor value C is changed, the central working frequency can vary with the capacitor value C so as to adjust the central working frequency of the low-noise amplifier. A frequency mixer proposed by the invention has a working voltage of 1.2 V and low power, accords with the requirements for low voltage and low power consumption and has great instruction meanings in aspects of simplifying a circuit structure, lowering the power consumption, expanding a central working frequency point, and the like.

Description

Technical field [0001] This technology designs a low-noise amplifier in an UHF RFID reader with adjustable working frequency. The low-noise amplifier maintains the performance of the traditional low-noise amplifier, but also realizes the adjustable working frequency, which belongs to analog integration. Circuit field. Background technique [0002] RFID is the abbreviation of Radio Frequency Identification, that is, radio frequency identification technology. It is a kind of automatic identification technology. It conducts non-contact two-way data communication through radio frequency to identify the target and obtain relevant data. According to the working frequency, the RFID system can be divided into: 1) low frequency system: the working frequency is generally 30∽300KHz, the typical working frequency is 125KHz, 133KHz; 2) the medium and high frequency system: the working frequency is generally 3∽30MHz, the typical working frequency 13.56MHz; 3) UHF and microwave systems: the op...

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Problems solved by technology

[0010] However, in the current LNA design, its operating frequency is generally fixed, and several operating frequencies cannot be converted to each other at the same time, that is, the center operating frequency cannot be adjusted, which is necessary to work at multiple operating frequencies. is a significant limitation for systems with

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