A SPDT RF Switch Small- and Large-Signal Characteristics on TR-HR SOI Substrates

This paper evaluates the small- and large-signal characteristics of a single pole double thru (SPDT) RF antenna switch including its insertion loss, isolation, and nonlinear behavior. It is fabricated on three different types of high resistivity (HR) silicon-on-insulator (SOI) substrates: one standard (HR-SOI) and two trap-rich (RFeSI80 and RFeSI90). Using a special test structure, the contribution of substrate and active devices is separated for both in small- and large-signal. It is shown that by using trap-rich substrate technology, a reduction of over 16 dB of 2nd harmonic is achieved compared with HR SOI substrate. In off-state, it is shown that 35 dB increase of harmonic level is due to the nonlinearity of active devices. The effect of body bias on small- and large-signal FoMs of the SPDT is investigated and discussed. It is illustrated that trap-rich HR-SOI substrates having much thinner BOX, still outperform classical HR-SOI wafer.