Compact Multipole GaN-on-Si SPDT Switch Using Inductive Parasitic Effects of Hybrid HEMT Devices

This article proposes a compact multipole single-pole double-throw (SPDT) switch using hybrid HEMT devices in the GaN-on-Si process. As investigated, the inductive effect of HEMTs is unwanted and usually alleviated in most reported switches for good impedance matching and high isolation. A different idea is proposed in this work, and the inductive effects of HEMTs are utilized to realize two extra transmission poles (TPs). For quantitative analysis, the circuit model and parasitic parameter extraction of two types of GaN HEMTs are investigated. The first type of HEMT has large ON-state self-inductance and small OFF-state capacitance, which is used in series for multiple TPs and high isolation. For low transmission loss and high isolation, the second type of HEMT is placed in parallel due to its low ON-state resistance and ON-state inductance. For verification, an SPDT switch with good in-band return loss and flatness is designed. Three TPs can be realized using a simple series-shunt topology, and the core chip size is only 0.39 mm2. The 1-dB bandwidth is from dc to 30 GHz with a minimum insertion loss of 0.5 dB, and the power capability is over 31 dBm.