SPDT Switch Using λ/9-TL-Based-λ/4-TL and DTMOS With Floating R for 28-GHz 5G New Radio

We demonstrate an asymmetrical single-pole double-throw (SPDT) switch with low insertion loss (IL) and high isolation and power linearity for 28-GHz 5G new radio. In the transmit (TX) path, a series equivalent quarter-wavelength ( $\lambda $ /4) transmission line (TL) (consisting of $\lambda $ /9 TL and transistors’ intrinsic parasitic C) and a parallel dynamic-threshold MOSFET (DTMOS) transistor with a body floating resistance (DTMOS-R) are included for low IL in the TX mode and good isolation in the receive (RX) mode. In the RX path, a parallel DTMOS-R and a series impedance (consisting of a TL and a DTMOS-R in parallel) are included for decent IL in the RX mode and isolation in the TX mode. In the TX mode, the SPDT switch achieves the measured IL of 0.75 dB at 28 GHz and 0.67–1 dB for 18.2–34.7 GHz (i.e., a bandwidth of 16.5 GHz) and the measured isolation (between TX and RX) of 60.7 dB at 26 GHz and 20–60.7 dB for 18.2–34.7 GHz, one of the best IL and isolation results ever reported for millimeter-wave CMOS SPDT switches. The measured input 1-dB compression point (P1dB) is 24.1 dBm at 28 GHz. Moreover, in the RX mode, the SPDT switch achieves the measured IL of 2.55 dB at 28 GHz and 1.89–2.69 dB for 26.5–58 GHz (i.e., bandwidth of 31.5 GHz) and isolation (between antenna and TX) of 19 dB at 28 GHz and 18.6–23.2 dB for 26.5–58 GHz. The measured P1dB is 28.5 dBm at 28 GHz.