Miniaturized Reconfigurable 28 GHz PCM-Based 4-bit Latching Variable Attenuator for 5G mmWave Applications

This paper reports a novel millimeter-wave (mmWave) reconfigurable phase change material (PCM) germanium telluride (GeTe) based 4-bit latching variable attenuator. The proposed variable attenuator is designed using PCM single-pole double-throw (SPDT) switches monolithically integrated with four passive bridged-T resistor network based fixed attenuators to provide wide attenuation range. The PCM switching units are latching type thus consume no static dc power. The integrated planar resistors are fabricated precisely on-wafer to get wide-band operation at desired 8 GHz frequency band. The device is fabricated in-house using a seven-layer microfabrication process. The proposed device is highly miniaturized with device area of 0.52 mm
²
. At the centre frequency of 28 GHz, the measured attenuation level varies from 4.7 dB to 37 dB with 16 discrete steps. The attenuator can be reconfigured at a tuning speed of less than 1µs,