Dual Micro-Structured Electrode Improves Performance Over Standard Bus-Design Coplanar Waveguides

Abstract

The University of Central Florida invention is a planar transmission line structure that can be engineered to not only reduce interconnect losses but also serve as a radio-frequency (RF) delay line for chip, board, and long-haul interconnects. RF transmission lines provide the interconnection of all chip-level communications between transistor structures, as well as the board-level traces connecting memory, processing, and I-O commands. In the last several decades, these lines' applications have expanded to act as traveling wave electrodes for many photonic devices, enabling the flow of internet traffic for server-level interconnects as well as long-haul communications over fiber.

With the introduction of wideband delay lines, chip-level routing constraints may be relaxed to avoid race conditions between gates during layout. Additionally, when coupled with optical Bragg grating structures, the optical propagation tunability improves device performance in RF photonic device designs, thanks to enhanced velocity matching between the optical and radio-frequency wave propagation coefficients. Improving velocity matching is incumbent on the optical grating structure and is done independently from any changes to RF propagation caused by adding the electrode microstructures.

Technical Details: The UCF invention offers improved systems and methods for greater engineering flexibility across a variety of platforms such as radio-frequency integrated circuits (RFICs) and photonic integrated circuits (PICs). Enabling the addition of specialized microstructures, the technology can be added to a traditional coplanar microwave transmission line to enhance the inductive and capacitive properties of the line. Thus, it provides better distribution and control of radio-frequency signals on chip-level structures. Applications include radio frequency (RF) photonics, RF delay lines, analog/digital signal processing, and optical interconnects.

In one example, a system can include an electrode with a main portion extending along a longitudinal axis. Multiple T-shaped sub-electrodes extend laterally from the main portion. Likewise, multiple inductive sub-electrodes extend laterally from the main portion. The inductive sub-electrodes interdigitate with the T-shaped sub-electrodes to form an alternating pattern with the T-shaped sub-electrodes in a lengthwise direction along the longitudinal axis. Additionally, a second electrode with a second main portion can extend parallel to the longitudinal axis, with a gap between the second electrode and the T-shaped sub-electrodes.

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