Design of a Dual-Band Low-Noise Amplifier with a Novel Matching Structure

Area of Science:

• Electrical Engineering
• Microwave Engineering
• RF Circuit Design

Background:

• Low-noise amplifiers (LNAs) are critical components in wireless communication systems.
• Dual-band operation is increasingly important for modern multi-standard devices.
• Existing dual-band LNA designs often face challenges with complexity and component count.

Purpose of the Study:

• To propose and validate a novel method for designing a dual-band low-noise amplifier (DB-LNA).
• To introduce an improved complex impedance dual-band transformer (IDBT) for enhanced DB-LNA performance.
• To demonstrate a simplified, cost-effective, and tunable DB-LNA solution.

Main Methods:

• Design of a new improved complex impedance dual-band transformer (IDBT) using parallel-coupled lines and series microstrip lines.
• Integration of the IDBT with a BFP840ESD transistor for a single-stage DB-LNA.
• Fabrication and testing of the designed Printed Circuit Board (PCB) prototype.

Main Results:

• The designed 2.4/5.5 GHz DB-LNA achieved a high S21 (gain) of 20.3/14.7 dB.
• Excellent input and output matching were observed with S11 of -29.8/-20.3 dB and S22 of -15.2/-16.4 dB.
• A low noise figure (NF) of 1.6/1.6 dB was measured, indicating high sensitivity.

Conclusions:

• The proposed IDBT effectively transforms complex impedances at dual frequencies without DC blocking capacitors.
• The developed DB-LNA exhibits a simple structure, low cost, and superior performance characteristics.
• The design is easy to tune, offering practical advantages for wireless applications.