Microstrip Power Combiners for V-Band Solid-State Power Amplifiers

This paper analyzes the most popular microstrip power combiners for output power combining in millimeter-wave solid-state power amplifiers (SSPAs). Wilkinson, Gysel, and T-junction power combiners are compared with respect to nominal insertion loss and isolation, as well as robustness to fabrication variations and varying termination impedances. This work also presents the design of an 8:1 Gysel microstrip power combiner for SSPAs at V band operating frequencies from 71-76 GHz. Full-wave electromagnetic simulation results for the designed 8:1 Gysel power combiner demonstrate a worst-case 8:1 combiner insertion loss of -2.7dB and worst-case isolation of -16.5dB. The 8:1 combiner consumes 16.8mm × 11.2mm of area.