This paper presents a broadband millimeter-wave power amplifier with a combination of 2-way, each of which consist of a distributed amplifier and cascaded single-ended stages for high gain and output power. To the best of our knowledge, it is the first time that the two amplifiers based on a distributed stage and cascaded single-ended stages have been combined for high power. As a result, the saturated power is improved up to more than 20.5 dBm in the frequency band of 33-66 GHz. Meanwhile, by combining distributed amplifier and cascaded single-ended stages methods, the power amplifier has inherent advantages of high gain and wide bandwidth. Moreover, to improve the gain flatness, small resistor-capacitors in bias circuits are introduced in the cascaded single-ended stages amplifier structure, so the measured S21 is improved to 21.8±0.6 dB in the 38-67 GHz band. These results show that high gain with good flatness and power can be achieved using the proposed method.

A three-stage monolithic microwave integrated circuit (MMIC) power amplifier from 6-18 GHz, which achieves high output power with excellent efficiency, is designed, fabricated and tested. Measured results show that the saturated output power and the small signal gain are about 32 dBm and 23 dB, respectively. Thus, the power added efficiency of about 28% indicates that it is useful in various communication systems.