Wideband Asymmetric Single-Pole Double-Throw Switch Based on Back-to-Back Coupler Structure

In this letter, a wideband asymmetric single-pole double-throw (AS-SPDT) switch equipped with a back-to-back coupler structure is presented for fifth generation millimeter-wave band applications. By employing a back-to-back connection from two couplers, a balanced structure in the Rx mode and a reflection-type structure in the Tx mode are combined into a single circuit; a control signal is used to switch between the Rx and Tx modes. These two structures extend the 3-dB bandwidth (BW) and improve the isolation. The on-state transistor of the reflection-type structure can be controlled to improve
$P_{\mathrm{ 1dB}}$
in the Tx mode. The proposed AS-SPDT switch supports 28 and 38 GHz operation; the measured 3-dB BWs are 48 and 53 GHz in the Rx and Tx modes, respectively. In the Rx mode, the measured
${\mathrm{ IP}}_{\mathrm{ 1dB}}$
values are 12 and 13 dBm at 28 and 38 GHz, respectively. In the Tx mode, the measured
${\mathrm{ IP}}_{\mathrm{ 1dB}}$
values are 29 and 27 dBm at 28 and 38 GHz, respectively. In the available 3-dB BW, the proposed AS-SPDT switch has a wider 20-dB isolation BW than the other works. These results indicate that the proposed switch has wider 3-dB BW, better linearity, and high isolation than the other works.