A Ka-band MMIC Doherty Power Amplifier using GaAs pHEMT technology

A fully integrated Ka-band Monolithic microwave integrated circuit (MMIC) Doherty Power Amplifier (PA) is designed and demonstrated in this paper. The proposed Doherty PA maily consists of a Lange coupler, carrier amplifier branch, peaking amplifier branch and impedance transformer network. offset lines are introduced in each branch to overcome the inherent defects of conventional Doherty PA. Electromagnetic (EM) simulated results show the proposed Doherty PA obtains a small signal gain over 5.5dB from 31GHz to 35GHz with a compact die size of 2mm×1.7mm. Power added efficiency (PAE) is over 19.8% at 6dB back-off with saturated output power over 26dBm.