Design of An Ultra-Compact Bidirectional Amplifier in 55-nm CMOS

This paper proposes a novel compact bidirectional amplifier topology utilizing transformers stacking technology. This solution employs magnetic self-canceling technique to fully stack the low-noise amplifier (LNA) within the power amplifier (PA), resolving performance and area trade-offs inherent in traditional bidirectional amplifier architecture. To validate this approach, we implemented a bidirectional amplifier with switchable LNA/PA operating modes for K/Ka-band satcom systems using 55-nm CMOS technology. The proposed bidirectional amplifier achieves a peak saturated power (Psat) of 11.9 dBm and output power of 1 dB (OP1dB) of 10.4 dBm in the PA mode while maintaining a minimum noise figure (NF) of 4.3 dB in the LNA mode. The core size of this proposed design is only 0.14 mm², which is only 20%-50% of the size occupied in conventional works.