Dual-band coupling low-noise amplifying circuit and amplifier

A dual-band coupling low-noise amplifying circuit, comprising an input frequency dividing circuit, a high-frequency amplifying circuit, a low-frequency amplifying circuit and an output combining circuit;

• wherein the input frequency dividing circuit comprises a first duplexer, a first capacitor and a second capacitor;
• the first capacitor is connected in parallel to a through port of the first duplexer;
• the second capacitor is connected in parallel to an isolation port of the first duplexer;
• an input end of the high-frequency amplifying circuit is connected with a coupling port of the first duplexer;
• an input end of the low-frequency amplifying circuit is connected with the through port of the first duplexer;
• the first capacitor and the second capacitor are grounded in parallel;
• the output combining circuit comprises a second duplexer, a third capacitor and a fourth capacitor;
• the third capacitor is connected in parallel to an isolation port of the second duplexer;
• the fourth capacitor is connected in parallel to a through port of the second duplexer;
• an output end of the high-frequency amplifying circuit is connected with a coupling port of the second duplexer;
• an output end of the low-frequency amplifying circuit is connected with an input port of the second duplexer;
• the third capacitor and the fourth capacitor are connected to ground in parallel;
• and
• after the input frequency dividing circuit divides received radio frequency signals into high-frequency signals and low-frequency signals, the high-frequency signals are input into the high-frequency amplifying circuit for a power amplification, and the low-frequency signals are input into the low-frequency amplifying circuit for the power amplification, and the output combining circuit couples and outputs the high-frequency signals and the low-frequency signals after the power amplification.