High Linearity DC-38 GHz CMOS SPDT Switch

In this paper, we demonstrate a low-loss and high-linearity DC-38 GHz CMOS SPDT switch for 5G multi-band communications in 0.18 μm CMOS. Traveling-wave matching (CLCL network) is used for the output-port (ports 2 and 3) matching and isolation enhancement, while π-matching (CLC matching) is adopted for the input-port (port 1) matching. Positive/negative gate-bias is adopted for linearity enhancement because larger Pin (i.e., AC signal with larger negative Vin) is required to conduct the off-state series switch transistor. Negative-body bias is used for insertion-loss reduction because the off-state series switch transistor is closer to an open state. The SPDT switch achieves insertion loss of 0.4–1.4 dB, 3.6–4.3 dB, and 4.5–5.9 dB, respectively, for DC-6 GHz, 21–29 GHz, and 31–38 GHz. Moreover, the SPDT switch achieves isolation of 37.5–59.4 dB, 25.7–28.7 dB, and 24.3–25.2 dB, respectively, for DC-6 GHz, 21–29 GHz, and 31–38 GHz. At 28 GHz, the SPDT switch achieves remarkable input 1-dB compression point (IP1dB) of 25.6 dBm, close to the simulated one (28 dBm). To the authors’ knowledge, this is one of the best IP1dB results ever reported for millimeter-wave (mm-wave) SPDT switches.

Laterally Movable Triple Electrodes Actuator toward Low Voltage and Fast Response RF-MEMS Switches

A novel actuator toward a low voltage actuation and fast response in RF-MEMS (radio frequency micro-electro-mechanical systems) switches is reported in this paper. The switch is comprised of laterally movable triple electrodes, which are bistable by electrostatic forces applied for not only the on-state, but also the off-state. The bistable triple electrodes enable the implementation of capacitive series and shunt type switches on a single switch, which leads to high isolation in spite of the small gap between the electrodes on the series switch. These features of the actuator are effective for a low voltage and fast response actuation in both the on- and off-state. The structure was designed in RF from a mechanical point of view. The laterally movable electrodes were achieved using a simple, low-cost two-mask process with 2.0 µm thick sputtered aluminum. The characteristics of switching response time and actuation voltage were 5.0 µs and 9.0 V, respectively.