Design of X-Band GaN LNA MMIC with Switched Impedance Network for Improved Noise Figure

In this work, an X-band gallium nitride (GaN) low-noise amplifier (LNA) monolithic microwave integrated circuit (MMIC) with a switched impedance network for improved noise performance is designed and fabricated using a 0.25 μm GaN WIN-semiconductor process. Notably, the term "switched impedance network" not only refers to the role of isolating receive and transmit paths, which is typically performed by a switch, but also signifies the utilization of a switch as a matching network. The size and matching loss of the proposed MMIC is minimized by replacing the LNA input-matching network with a single-pole double-throw switch. The fabricated LNA MMIC exhibits a noise figure of 1.9–2.3 dB, gain of 16–17 dB, and input/output return loss of 6–30 dB at a frequency range of 8–10 GHz. Under pulse conditions, it presents a maximum input power of 37 dBm and a saturated output power of 19 dBm.