A Programmable Complex Impedance IC for Scalable and Reconfigurable Meta-Atoms

Abstract

This article presents the design of a fully-custom integrated circuit (IC) suitable for adjusting the complex impedance of individual meta-atoms to enable programmability of metasurface systems. Implemented in a 0.18 µm mixed-signal CMOS process, the circuit utilizes four integrated complex impedance elements, each one with 2 16 available states. The impedance elements are optimized between 2-6 GHz, thus covering the entire S-band as well as half of the C-band. An asynchronous digital control circuit based on Quasi Delay Insensitive (QDI) circuits has been employed, offering basic communication capabilities and software programmability, but most importantly, the clockless operation allows for extreme scalability, ultra-low static power consumption and low electromagnetic (EM) radiated emissions. An array of meta-atoms utilizing the ICs can form metasurfaces with arbitrary sizes and shapes, on both rigid and flexible substrates, adjusting their surface impedance without interfering with incoming EM waves. Measurement results of the 2.2 mm × 2.2 mm IC demonstrate that it achieves a reconfiguration frequency of 1 MHz for all loading elements, whilst consuming 324 µW static power consumption.

A review of light‐controlled programmable metasurfaces for remote microwave control and hybrid signal processing

“…[72][73][74][75][76][77] Information metasurface bridges the physical world and digital world, which provides an efficient platform for controlling wave-information-matter interactions, thus enabling many attractive devices and systems, such as simplified-architecture transmitter, 64,77 real-time imager, 49,78 programmable radar, 75 and so on. [79][80][81][82][83] Electrical control is a popular way to achieve programmable metasurfaces. However, it needs to design additional direct-current (DC) bias networks on metasurface, which will affect its EM performance and increase overall design difficulty.…”

“…More importantly, because of real‐time switching capability, programmable metasurface can realize information processing while manipulating EM fields and waves, giving rise to a new concept of information metasurface 72‐77 . Information metasurface bridges the physical world and digital world, which provides an efficient platform for controlling wave‐information‐matter interactions, thus enabling many attractive devices and systems, such as simplified‐architecture transmitter, 64,77 real‐time imager, 49,78 programmable radar, 75 and so on 79‐83 …”