Design and Analysis of SPDT Switch and Array Antenna for 28GHz 5G New Radio

We report a low-insertion-loss (IL), high-isolation, and high-linearity CMOS SPDT switch and a 4×4 array antenna for 28 GHz 5G NR. The transmit (TX) path consisting of a parallel DTMOS transistor M₁ with a large R (DTMOS-R), a series λ/8 transmission line (TL), and a parallel capacitance (Cant). The λ/8-TL in conjunction with the parallel Cant and parasitic capacitance of transistors M₁/M2 constitute an equivalent λ/4-TL with ZC of 50 Ω. This leads to low IL in TX mode and decent isolation in receive (RX) mode. The RX path is an L-network constituting a series impedance and a parallel DTMOS-R M₃. This leads to high linearity in RX mode and decent isolation in TX mode. In TX mode, the SPDT switch achieves measured IL of 0.58–1 dB for 17–34.9 GHz, isolation of 25.6–62.3 dB for 17–34.9 GHz, and P1dB of 28.5 dBm at 28 GHz. These are one of the best IL and isolation results ever reported for mm-wave SPDT switches. In RX mode, the SPDT switch achieves measured IL of 1.9 dB, and isolation of 25 dB. The 4×4 array antenna achieves minimum S11 of -40.4 dB at 28.85 GHz and S11 smaller -10 dB for 28.5–31.1 GHz, and decent gain of 10.1 dB at 30 GHz.