Design and Analysis of a Dual-Band Balanced Filtering Low-Noise Amplifier Integrated With Diplexing Function

This letter presents a novel dual-band filtering balanced low-noise amplifier (LNA), in which the diplexing function is realized through the integration of a coupler, eliminating the need for a conventional diplexer, and thereby enhancing system integration. To demonstrate the feasibility of the proposed architecture, a balanced diplexing LNA operating at 1.58 and 2.86 GHz has been designed, fabricated, and measured. The measurement results indicate that the circuit achieves gains of 20.2 and 19.2 dB, with noise figures of 0.85 and 1.21 dB at 1.58 and 2.86 GHz, respectively. In addition, the proposed design provides effective diplexing and filtering functions at both frequency bands, offering an efficient and compact solution for diplexing receiver communication systems.