Highly adaptive, instinctively interference-tolerant radio frequency (RF) receivers are in high demand today. To achieve high-interference robustness at low average power, receivers need to be dynamically configured to operate in low-power mode in the absence of interference and a high-power interference-tolerant mode as an “instinctual” response to the blocker. In this letter, we present an interference-adaptive receiver with a control loop and on-board commercial off-the-shelf (COTS) components that adapt a 2–6-GHz low-noise amplifier (LNA) from a low-power mode (−10-dBm $P_{\text {1 dB,IN}}$ and $\approx 280$ -mW power) to high-linearity mode (1.5-dBm $P_{\text {1 dB,IN}}$ and $\approx 1.4$ -W power) where the linearity is increased by 11.5 dB ( $> 14\times $ ) with a $5\times $ increase in consumed power. With no interference, the control loop automatically brings the LNA back to the low-power mode.

Instinctual Interference-Adaptive Low-Power Receiver With Combined Feedforward and Feedback Control

One of the major challenges in communication, radar, and electronic warfare receivers arises from nearby device interference. The paper presents a 2-6 GHz GaN 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\textsubscript{1dB,IN}=-10.5 dBm 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 $\leq$10$\%$ (100 mW) of nominal LNA power (1 W) to achieve an adaptation time<1 ms.

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

This paper shows how the signal-to-noise and distortion ratio (SNDR) for low noise amplifiers (LNA) can be derived from the commonly specified parameters noise figure, gain, third order output intercept point and 1 dB compression point. The parameters dependency of the biasing of the amplifier are also incorporated which enables the possibility to study how SNDR can be optimized for different operating conditions by dynamically change the gate- and drain voltage. An experimental verification shows that improvements in SNDR can be achieved by selecting gate- and drain voltage of the LNA according to the level of the input signal power.

Marie Strom

Papers

Optimizing the Signal-to-Noise and Distortion Ratio of a GaN LNA using Dynamic Bias