A W-Band Balanced Power Amplifier Using Broadside Coupled Strip-Line Coupler in SiGe BiCMOS 0.13-μm Technology

Load-variation insensitivity, for impedance matching between power amplifiers (PAs) and transmitting antennas, contributes to challenging the design of millimeter-wave wireless systems. In this paper, a W-band two-way balanced PA based on a compact quadrature coupler with a broadside coupled stripline (BCSL) as the core is presented to enhance the load-variation insensitivity and stability. The proposed coupler is truly broadband with low amplitude and phase imbalance. The proposed W-band balanced PA achieves higher power-added efficiency (PAE) and unsaturated output power P-sat over wide frequency bandwidth. The W-band balanced PA is implemented in a 0.13-mu m SiGe BiCMOS process and achieves a measured P-sat of 16.3 dBm and a peak PAE of 14.1% at 100 GHz (with 1.6-V power supply). The measured P-sat with 1-dB bandwidth is from 91 to 102 GHz. The measured results present the feasibility of the compact quadrature coupler. The total chip surface area (with pads) is 0.64 mm(2), where the size of the proposed quadrature coupler area is only 0.04 mm(2).