Performance of a Marchand balun at Q band in Silicon Germanium (SiGe) technology

Abstract:
The paper reports on the design and characterization at Q band of a compact, integrated Marchand balun with state-of-the-art performance. The balun’s goal is to bring a differential signal delivered by a medium power amplifier (PA) stage to a single-ended output pad. The balun must allow a DC source to bias the PA stage. The practical design constraints on the balun are discussed and a simple, yet effective, design methodology is suggested. The balun has been EM-simulated as a 4-port network to account for the DC input before fabricating it in IBM’s SiGe 8HP process. Experimental results confirm the design approach.