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.