We present a theoretical study on the performance of graphene-loaded coplanar waveguide switches for 5G and beyond applications. Therefore, we exploit the tunable properties of graphene to device cost-effective, large-scale, broadband sub- millimeter-wave switches. Given the sheet impedance of biased and unbiased graphene monolayers, the model provides the optimum switching ratio with respect to insertion loss, characteristic impedance of transmission line, and graphene geometry. Using measured graphene sheet resistance, we compute the optimum switching performance for series and shunt single- pole-single-though sub-millimeter-wave (220-330 GHz) switches.
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Modeling and Analysis of Terahertz Graphene Switches for On-Wafer Coplanar Transmission Lines
We present an analysis of graphene-loaded transmission line switches for sub-millimeter wave and terahertz applications. As such, we propose equivalent circuit models for graphene-loaded coplanar waveguides and striplines and examine the switching performance under certain parameters. Specifically, we identify the optimum design of graphene switches based on transmission line characteristic impedance, scaling factor, graphene shape, and topology (series or shunt). These parameters are varied to obtain the insertion loss and ON/OFF ratio of each switch configuration. The extracted results act as the design roadmap toward an optimum switch topology and emphasize the limitations with respect to fabrication challenges, parasitic effects, and radiation losses that are especially pronounced in the millimeter wave/terahertz bands. This is the first time that such an in-depth analysis is carried out on graphene-loaded transmission line switches, enabling the development of efficient millimeter wave/terahertz tunable topologies in terms of insertion loss and ON/OFF ratio. Specifically, the optimized switches can be integrated with antennas or employed for the development of tunable phase shifters, leading to the implementation of efficient reconfigurable reflective surfaces (e.g., reflectarrays) or coded phased arrays either for imaging or wireless communication applications. In our models, we use measured graphene values (sheet impedance) instead of theoretical equations, to obtain the actual switching performance. Moreover, the proposed study can be easily expanded to other thin film materials that can be characterized by a sheet impedance including vanadium dioxide and molybdenum disulfide. Finally, the proposed equivalent models are crucial for this in-depth study; since we simulated more than 2,000,000 configurations, a computationally challenging task with the use of full-wave solvers.
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- Award ID(s):
- 1847138
- NSF-PAR ID:
- 10215761
- Date Published:
- Journal Name:
- Journal of infrared millimeter and terahertz waves
- Volume:
- 41
- ISSN:
- 1866-6892
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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