A D-band Bi-directional Amplifier Utilizing Lossy U-boosting Network

This paper proposes a D-band bi-directional amplifier using a lossy U-boosting network with off-state transistors, pre-embedded inductors, and a Wheatstone-bridge-like feedback network to enhance Mason’s invariant while increasing MAG/MSG. When the boosted Mason’s invariant becomes negative, conventional gain-plane optimization is ineffective; to overcome this, we introduce a Network Navigator that remains valid for any magnitude/sign U and whose trajectory is directly inferred from circuit parameters without approximation.