Design Insights Into Sixth-Order Matching Networks for a 105–175-GHz Ultra-Wideband SiGe BiCMOS LNA

This article presents a systematic methodology for designing ultra-wideband 6th-order matching networks, tailored for D-band low-noise amplifiers (LNAs) in SiGe BiCMOS technology. The adopted topology fully absorbs parasitics while embedding signal interconnections, biasing, and power routing. By modeling the network as a doubly tuned transformer and leveraging embedded resonances, impedance transformation and bandwidth expansion are effectively controlled. The analysis uses network decomposition and simplifications that preserve design intuition while ensuring accurate performance predictions. A step-by-step design example illustrates the methodology, guiding key component choices and demonstrating its practical application. The approach is validated through a three-stage D-band LNA, achieving a −3-dB bandwidth from 105 to 175 GHz, a peak gain of 23 dB, and a noise figure (NF) of 5–6.5 dB. Measurements confirm that the performance is also maintained with the LNA mounted into an eWLB package interfaced with waveguides. Experimental results compare favorably against previous works and prove the effectiveness of the proposed design flow to maximize the gain–bandwidth performance.