CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Greek Patent Application No. 20180100212, filed May 18, 2018, entitled “Reduced Dispersion Dielectric Waveguides,” the contents of which are hereby incorporated by reference in their entirety.

TECHNICAL FIELD

This disclosure relates generally to the field of semiconductor devices, and more specifically, to millimeter (mm)-wave dielectric waveguides with improved dispersion characteristics.

BACKGROUND

As more devices become interconnected and users consume more data, the demand on improving the performance of servers has grown at an incredible rate. One particular area where server performance may be increased is the performance of interconnects between components, because there are many interconnects within server farm and high-performance computing (HPC) architectures today. These interconnects include within blade interconnects, within-rack interconnects, and rack-to-rack or rack-to-switch interconnects. To provide the desired performance, these interconnects may need to have increased data rates and switching architectures which require longer interconnects. Furthermore, due to the large number of interconnects, the cost of the interconnects and the power consumption of the interconnects should both be minimized. In current server architectures, short interconnects (e.g., within-rack interconnects and some rack-to-rack interconnects) are achieved with electrical cables, such as Ethernet cables, co-axial cables, or twin-axial cables, depending on the required data rate. For longer distances (e.g., greater than five meters), optical solutions are employed due to the long reach and high bandwidth enabled by fiber optic solutions. Optical interconnects may utilize optical interconnect technology and various semiconductor technologies along with optical fibers.

However, as new architectures emerge, such as 100 Gigabit Ethernet, traditional electrical connections are becoming increasingly expensive and consume increasingly more power to support the required data rates for short (e.g., 2 meters to 5 meters) interconnects. For example, to extend the length of a cable or the given bandwidth on a cable, higher quality cables may need to be used or advanced equalization, modulation, and/or error correction techniques employed. Accordingly, these solutions require additional power and increase the latency to the system. Optical transmission over fiber can support the required data rates and distances, but at a severe power and cost penalty, especially for short to medium distances (e.g., a few meters). For some distances and data rates required in proposed architectures, there is no viable electrical solution today. For medium distance communication in a server farm, the overhead power associated with the optical fiber interconnects is too high, whereas the required error correction for traditional electrical fabric creates a substantial latency (e.g., several hundred nanoseconds). This makes both technologies (traditional electrical and optical) not particularly optimal for emerging rack-scale architecture (RSA) servers including HPCs, where most transmission ranges are between 2 and 5 meters.

One proposed interconnect technology that may provide high data rates with lower power consumption is mm-wave waveguide interconnect technology, where mm-wave waveguides propagate and guide mm-wave signals along a dielectric waveguide. Typically, the dielectric waveguide is also covered by a conductive coating (e.g., metallic) layer to provide electrical shielding to prevent cross-talk or other interference. Dielectric waveguides are beneficial because they provide low signal attenuation compared to traditional electrical interconnects used in high speed input/output (I/O) technologies. However, the propagation of mm-waves along a shielded dielectric waveguide may be dispersion-limited, depending on the specific waveguide architecture, where dispersion refers to the phenomenon that not all frequencies have the same velocity as they are propagated through the dielectric material of the dielectric waveguide. The dielectric waveguide may be loss-limited if the incurred dispersion over the length of the channel is not significant (typically in pure dielectric waveguides) or may be dispersion and loss limited if the length of the channel is significant (typically in metal air core waveguides). Accordingly, in longer mm-wave waveguides the signal may incur excessive dispersion and spread too much, therefore, becoming difficult to decode at the receiving end and hence limiting the maximum reach and/or data rate of the dielectric waveguide.

