Single Pole Double Throw Discrete Switch using Switchable Microstrip Line Resonators for Millimeter Wave in 26/28 GHz Band

A single pole double throw (SPDT) discrete switch design using switchable microstrip line resonators is proposed in this paper. It is targeted for the RF front-end system in a 5G millimeter wave in 26/28 GHz band. High isolation between transmitter and receiver (in the transceiver) is needed in SPDT switch design to minimize any high RF power leakage in the receiver. Therefore, the use of microstrip line resonators can achieve high isolation in the SPDT where the isolation depends on the bandstop response of the microstrip line resonators. These resonators can be switched between allpass and bandstop responses to allow the operation between transmit and receive modes in the SPDT switch. As a result, the simulation and measurement showed that the proposed SPDT switch produced an isolation higher than 30 dB in from 24.25 to 27.5 GHz.