Design of a High-Gain Multi-Input LNA with 16.4 Degree Phase Shift Within the 32 dB Gain Range

This paper presents a high-gain multi-input low-noise amplifier (LNA) design aimed at achieving stable phase and minimal noise within a flexible gain range for modern wireless communication systems. The proposed LNA, designed using a CASCODE architecture and implemented in a 65 nm silicon-on-insulator (SOI) process, demonstrates significant improvements in isolation, noise reduction, and miniaturization. The SOI process reduces parasitic capacitance, enhancing performance and thermal/electrical isolation, critical for high-frequency applications. The CASCODE structure minimizes unwanted coupling between stages, enhancing signal integrity and maintaining stable operation across multiple gain modes. The LNA operates in the 2.3 GHz to 2.69 GHz frequency band and supports seven gain modes. It achieves a maximum gain of 21.45 dB with a noise figure of 1.03 dB at the highest gain mode. Notably, it maintains phase stability within 16.4 degrees across the entire gain range, ensuring consistent phase alignment, which is crucial for applications requiring precise signal alignment. The design eliminates the need for switching mechanisms typically used in conventional LNAs, which often introduce additional noise. This work demonstrates that the CASCODE-based multi-input LNA, implemented in a 65 nm SOI process, successfully meets the rigorous demands of high-frequency communication systems, achieving an optimal balance between gain flexibility, noise reduction, and stable phase control within a 32 dB gain range.