Developing PCM-Based Microwave and Millimetre-Wave Switching Networks by Optimised Building Blocks

Abstract

The implementation of microwave and millimetre-wave switching networks using phase change material (PCM) is presented in this paper. We propose integrating a combination of ultra-wide bandwidth-optimised building cells into a unique semi-T type switch. The construction of arrays with different dimensions is enabled. The present paper selected GeTe for the PCM-based switches, which are 150 nm GeTe thin-film offering on- and off-state σon = 37,203,703 S/m and σoff = 94.97 S/m conductivities by a customised eight-step fabrication process. The integrated semi-T switch cell with two, thru, and turn operational states allows easy expansion into the form of a staircase switch matrix. The simulated results for the semi-T type switch show excellent insertion loss of better than 0.8 dB, return loss of better than 20 dB, and isolation of 40 dB for both the thru and turn paths from DC to 120 GHz. The proposed 4 × 4 staircase switch matrix with a dimension of only 510 × 510 μm2 is also the smallest in its class. The switch matrix exhibits better than 17 dB return loss and 40 dB isolations across all possible combinations and paths.