Low noise amplifier and over distortion method based on same

Abstract

The embodiment of the invention discloses a low noise amplifier and over distortion method based on the low noise amplifier. The method of the invention includes that: the grids of two over distortion field effect tubes are respectively connected with the drain of corresponding low noise amplifier input tube by a stopping condenser, analysis in vector aspect is carried out to generate a three-order intermodulation coefficient vector capable of being offset with the three-order intermodulation coefficient vector of the amplifying circuit of the low noise amplifier, the aim of improving linearity of low noise amplifier by over distortion method is realized, more importantly, the method effectively reduces grid source parasitic capacitance and grid drain parasitic capacitance formed on the low noise amplifier input tube in the over distortion method, thus reducing parasitic capacitance, reducing influence of gain of amplifier and ensuring noise performance of low noise amplifier; and meanwhile, the parasitic capacitance is reduced while input impedance is hardly changed, thus being convenient for impedance matching of off chip matching circuit of the low noise amplifier.

Description

Technical field [0001] The present invention relates to the field of wireless communication technology, and more specifically, to an overdistortion method based on a low noise amplifier and a low noise amplifier. Background technique [0002] Linearity is a measure of whether the output and input system can maintain a normal proportional relationship (ie, linear relationship) like an ideal system. For wireless communication, poor linearity will reduce the spectrum utilization of the wireless communication system and worsen the bit error rate; in order to achieve better linearity, it is often necessary to improve the linearity of the equipment in the wireless communication system. Since the device at the front end of the wireless communication system is a low-noise amplifier, improving the linearity of the low-noise amplifier can greatly reduce the linearity requirements of other modules in the subsequent stages of the system, and can reduce the power consumption and chip area of ...

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Problems solved by technology

[0005] However, the above prior art has at least the following disadvantages: Although this method achieves the requirement of improving the linearity of the low-noise amplifier to a certain extent, because of its over-distortion, the gates of the MOS transistors MA1 and MA2 are directly connected by the DC blocking capacitors C1 and C2. Connecting to the gates of the main branch input MOS transistors M1 and M2 increases the gate-source parasitic capacitance and gate-drain parasitic capacitance of the main branch input MOS transistors, and reduces the low The noise performance of the noise amplifier (signal-to-noise ratio SNR, the ratio of the amplifier output voltage and the noise voltage output at the same time); Simultaneously, due to the actual existence of the parasitic capacitance, it brings the off-chip impedance matching of the low-noise amplifier difficulty

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