Bi-directional amplifiers for half-duplex transceivers

This paper reports a unique bi-directional amplifier (BDA) circuit that combines the symmetry of common-gate connected HEMTs with topologically mirrored input and output matching, Bi-directional behavior of the BDA is demonstrated on fabricated circuits, with identical performance in forward and reverse directions. Between 40 and 45 GHz, 10-dB gain and 8-dB input and output return losses have been measured.