A millimeter-wave wideband balanced amplifier using multilayer MMIC directional couplers

This paper describes a millimeter-wave wideband balanced amplifier using novel multilayer MMIC directional couplers. The 3 dB-couplers designed for a center frequency of 50 GHz show coupling losses of 3.9 dB ± 0.3 dB. The balanced amplifier fabricated in a 1.2 mm × 2.3 mm areas, shows a gain of 10-14 dB with input and output return losses of better than 14 dB from 34 to 52 GHz. The utilized directional couplers can be applied without degrading the circuit performance or increasing the circuit area. To our knowledge, this is the first millimeter-wave active circuit employing multilayer MMIC's.