Blocking signal cancellation low noise amplifier system

A blocking signal cancellation low noise amplifier system, comprising a first low noise amplifier, a second low noise amplifier, a blocking signal extraction and bias generation circuit, a bias switching circuit, and a bias switching signal generating circuit;

• wherein
• the first low noise amplifier is used for dynamic input matching, and the first low noise amplifier receives an input signal and outputs it after amplifying;
• the first low noise amplifier has a blocking mode and a small signal mode, and in the small signal mode, a bias signal of the first low noise amplifier is a DC bias voltage signal VB1, and in the blocking mode, the bias signal of the first low noise amplifier is a DC bias voltage signal VB2;
• the blocking signal extraction and bias generation circuit is used to extract a blocking signal from an output signal of the first low noise amplifier, and output a DC voltage signal having an inverse relationship with a strength of the blocking signal as the DC Bias voltage signal VB2;
• the bias switching circuit is used to switch the first low noise amplifier between the blocking mode and the small signal mode;
• the bias switching circuit switches the bias signal of the first low noise amplifier to the DC bias voltage signal VB1 to switch the first low noise amplifier into the small signal mode;
• the bias switching circuit switches the bias signal of the first low noise amplifier to the DC bias voltage signal VB2 to switch the first low noise amplifier into the blocking mode;
• the bias switching signal generating circuit is used to compare the DC bias voltage signal VB2 with a preset reference voltage signal Vref, and when the DC bias voltage signal VB2 is smaller than the preset reference voltage signal Vref, the bias switching signal generating circuit generates a first switching signal, and the first switching signal is used to make the bias switching circuit switch or maintain the first low noise amplifier in the blocking mode;
• otherwise, when the DC bias voltage signal VB2 is greater than the preset reference voltage signal Vref, the bias switching signal generating circuit generates a second switching signal, and the second switching signal is used to make the bias switching circuit switch or maintain the first low noise amplifier in the small signal mode;
• and
• the second low noise amplifier is connected to the first low noise amplifier, and is used to be biased by a class-A bias voltage VBA and a class-C bias voltage VBC at the same time, so as to control the output signal of the first low noise amplifier to perform block removal and amplification.