Fusion structure of LNA (low noise amplifier) and frequency mixer

Abstract

The invention relates to a fusion structure of an LNA and a frequency mixer. The fusion structure comprises a low noise transconductance amplifier stage, a switching frequency mixing stage and a resistance loading stage, wherein the low noise transconductance amplifier stage is divided into two parts, a first part adopts a cross coupling main-auxiliary noise offset technology, a main transconductance pipe adopts a cross coupling structure so as to double an equivalent transconductance value, an auxiliary transconductance pipe provides an appropriate transconductance value, and the noise of the main transconductance pipe is offset through the main-auxiliary structure; and a second part adopts a common-source-level structure, then gain is provided, direct current flowing through switching tubes is reduced, and flicker noise is reduced. The switching frequency mixing stage modulates radio-frequency current output from the low noise transconductance amplifier stage and outputs intermediate-frequency current, and source electrodes of two groups of switching tubes are connected through an inductor, so that the flicker noise is reduced, and the conversion gain is improved. The resistance loading stage adopts an RC (current limiting resistor) lowpass filtering network to convert the intermediate-frequency current into an intermediate-frequency voltage signal for outputting. The fusion structure of the LNA and the frequency mixer has the characteristics of low noise, high gain and low power consumption.

Description

technical field [0001] The invention relates to a frequency conversion receiver, in particular to a fusion structure of a low noise amplifier and a mixer. Background technique [0002] In the direct conversion receiver, the low noise amplifier and the mixer are used as the front-end circuit of the receiver, and its performance has a very important influence on the whole receiver. According to the formula of the cascaded noise figure of the system, the front-end circuit composed of the low-noise amplifier and the mixer should have a lower noise figure and a higher gain to suppress the impact of the noise of the subsequent stage circuit on the noise figure of the entire receiving chain . However, reducing the noise figure of LNAs usually comes at the cost of higher power consumption, which is a huge challenge for battery-operated equipment such as home automation and consumer electronics. Therefore, it is of great significance to study the RF receiving front end with low noi...

AI Technical Summary

Problems solved by technology

But the consequence of this is that a large parasitic capacitance is introduced at the source end of the switching mixing stage, and the constant current source itself does not provide gain but introduces noise

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