A 1–12 GHz Ultra‐Wide Band Bidirectional Amplifier Featuring Enhanced Loop Stability

ABSTRACT Bidirectional amplifiers (BDAs) are key components in RF communication systems, enabling efficient two‐way signal transmission over shared paths. Enhancing their performance is essential for improving signal integrity, reduce power loss, and increase overall system efficiency, particularly in compact and high‐frequency wireless applications. In this study, we report the design and fabrication of an ultra‐wideband BDA operating at 1–12 GHz using the GaAs 0.25 μm PHEMT process. we introduce a new common‐leg topology, which significantly improves the switching speed between transmit and receive (T/R) modes. We incorporate RLC negative feedback and peaking inductor techniques to ensure consistent gain flatness across the operating band of the developed amplifier and provide positive gain slope compensation. Moreover, we analyze the high‐frequency stability in the bidirectional signal paths by proposing a design methodology based on the loop stability model to guarantee unconditional stability. Our findings demonstrate a small‐signal gain exceeding 13 dB in both T/R modes over the full 1–12 GHz band of the amplifier, with input and output return losses better than 10 dB. The noise figure remains below 4 dB, and the output 1 dB compression point (OP‐1dB) is better than 14 dBm. Additionally, the amplifier exhibits stable performance across varying temperature conditions, indicating robust thermal reliability.