Sub-1-ms Instinctual Interference Adaptive GaN LNA Front End With Power and Linearity Tuning

One of the major challenges in communication, radar, and electronic warfare receivers arises from nearby device interference. This article presents a 2-6-GHz gallium-nitride (GaN) low-noise amplifier (LNA) front end with onboard sensing, processing, and feedback utilizing microcontroller-based controls to achieve adaptation to a variety of interference scenarios through power and linearity regulations. The utilization of GaN LNA provides high-power handling capability (30 dBm) and high linearity (OIP3 = 30 dBm) for radar and EW applications. The system permits an LNA power consumption to tune from 500 mW to 2 W (4x increase) in order to adjust the linearity from P-1 (dB,IN)= -10.5 to 0.5 dBm (> 10x increase). Across the tuning range, the noise figure increases by approximately 0.4 dB. Feedback control methods are presented with backgrounds from control theory. The rest of the controls consume <= 10% (100 mW) of nominal LNA power (1 W) to achieve an adaptation time < 1 ms.