Analysis of Common-Inductive-Bias Technique and Its Application to a W-Band SPDT Switch With Enhanced Isolation

This letter analyzes the common-inductive-biased dual-shunt switch circuits for millimeter-wave applications. With the introduced biasing inductor at control pins, the dual-shunt switches reveal >50% reduction in its equivalent off-capacitance at a proper inductor sizing, subsequently leading to improved switching ratio of isolation over insertion loss for a shunt switching cell. To validate the design theory, a $W$ -band single-pole-double-throw switch was designed and fabricated in a 0.13- $\mu $ m SiGe technology. The measured results show an operation bandwidth of 80–110 GHz, an in-band insertion loss of 1.8–3 dB, and an enhanced isolation of 32–47 dB. It demonstrates the highest ratio of isolation over insertion loss among similar silicon-based $W$ -band switches.