The present disclosure generally relates to the field of electronics. More particularly, an embodiment relates to phase heterogeneous interconnects for crosstalk reduction.
Interconnects used in many socket designs can introduce an appreciable amount of crosstalk, particularly when the interconnects are relatively long with a small separation between adjacent links in the interconnect. The crosstalk, in turn, may cause signal propagation delays, signal loss, and/or errors.
The detailed description is provided with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The use of the same reference numbers in different figures indicates similar or identical items.
In the following description, numerous specific details are set forth in order to provide a thorough understanding of various embodiments. However, various embodiments may be practiced without the specific details. In other instances, well-known methods, procedures, components, and circuits have not been described in detail so as not to obscure the particular embodiments. Further, various aspects of embodiments may be performed using various means, such as integrated semiconductor circuits (“hardware”), computer-readable instructions organized into one or more programs (“software”), or some combination of hardware and software. For the purposes of this disclosure reference to “logic” shall mean either hardware (such as logic circuitry or more generally circuitry or circuit), software, firmware, or some combination thereof.
As mentioned above, some current interconnect designs suffer from an appreciable amount of crosstalk which may, in turn, cause signal propagation delays, signal loss, and/or errors. To this end, some embodiments relate to phase heterogeneous interconnects for crosstalk reduction. In one embodiment, a phase diversified interconnect design is introduced to mitigate the overall crosstalk impacts imposed on a victim link from its adjacent aggressor(s) link(s), while maintaining the interconnect height/length and relatively small separations between the adjacent interconnect links. As discussed herein, an interconnect “link” generally refers to a signal path from an originator (such as a transmitter) to a destination (such as a receiver). Further, the terms interconnect link, link, an interconnect transmission line, a wire, or a pin from a plurality of links that may be interchangeable. In at least one embodiment, the interconnects discussed herein may utilize a differential signal pair which utilizes two wires to form a differential signal path.
In an embodiment, heterogeneous interconnects with diverse phase velocities are used to mitigate the overall crosstalk imposed upon a victim link from different adjacent aggressor link(s). The diverse phase velocities may be provided by adding capacitive diaphragms, e.g., to alter the phase velocities of each individual interconnect link. Such embodiments are envisioned to: (a) provide a higher data rate while the package density and the platform form factor remain unchanged; (b) maintain the mechanical stability of the interconnect; and/or (c) provide compatibility with at least some current Printed Circuit Board (PCB) and test socket pin fabrication technologies. Hence, there is little or no addition cost associated with implementation of one or more embodiments.
As shown in
Referring to
In an embodiment, the circular diaphragms or other structures 106 provide a capacitively loaded transmission line. For a homogenous transmission line, the phase velocity is given by:
Vp=√{square root over (LC)}=√{square root over (μrμ0εrε0)} (1)
where εr is the dielectric permittivity and μr is the magnetic permeability of the medium surrounding the transmission line. The phase velocity cannot be decreased by increasing the shunt capacity C per unit length because any change in the line configuration to increase C automatically decreases the series inductance L per unit length, since:
LC=μ0ε (2)
However, by removing the restriction that the transmission line should by physically smooth, an effective increase in the shunt capacitance per unit length can be achieved without a corresponding decrease in the series inductance L. That is, lumped shunt capacitance may be added at periodic intervals without affecting the value of L. If the spacing between the added lumped capacitors is small compared to the wavelength, it may be anticipated that the transmission line will appear to be electrically smooth, with a phase velocity by adding an additional:
where C0/d is the amount of lumped capacitance added per unit length (where a capacitor Co added at intervals d).
By introducing different C0/d values, the phase velocity of a transmission line can be altered. To maintain the impedance of the transmission line with no change, L can be adjusted accordingly. Besides the periodical loading of the transmission line capacitively, non-periodically loading of the transmission line provides much more flexibility to truly diversify the phase of which a transmission provides, and hence enables phase heterogeneous interconnects for crosstalk cancelation.
Accordingly, some embodiments provided one or more of the following: (a) phase velocity heterogeneous spring-loaded pins for a high-volume testing socket; (b) phase heterogeneous vias in a PCB; and/or (c) phase heterogeneous routing for a package PCB. As discussed herein, a “via” generally refers to a plated through-hole via or partial through-hole via (sometimes referred to as a blind or buried via) which may be utilized to communicate a signal between one or more layers of a PCB and/or between surface pads and one or more layers of the PCB. The (e.g., metal including copper, nickel, aluminum, etc.) plating of a via allows for the via to become electrically conductive. The PCBs discussed herein may mechanically couple the plurality of links. Further, a PCB may be surface finished with Hot Air Solder Leveling (HASL) finish, lead free HASL finish, or Electroless Nickel Immersion Gold (ENIG) finish.
Referring to
Moreover, the diameter of the pin structure and outer diameter of the circular diaphragms/features and/or thickness may be used to tune the inductance of that pin. For the tuning to take effect and show phase angle distribution, the structural diameters of the circular diaphragms/features are between approximately 20% and 30% more than the pin structure diameter in an embodiment. If the pin diameter is more than approximately 30% less the circular diaphragm diameter, then the pin inductance would not be enough to make a phase change. Thickness if the circular diaphragms is important along with the placement of these features along a signal pin to change the phase angle and interaction of adjacent pins. Pins adjacent to each other with different thickness in circular diaphragms show phase angle difference.
Further, both designs (
Since much of the crosstalk that exists in a channel generally occur at the PCB layer transitions, one or more embodiments can also be applied as phase heterogeneous vias in PCB. As discussed herein, a “channel” generally refers to an electrical channel that includes an entire path from silicon driver circuit (TX) through its substrate package and/or solder joint, and then to main board traces and vias, finally reaching the solder joint, substrate package and silicon receiver circuit (RX). Also, as discussed herein, a “pad stack” refers to all features associated with a conductive circular disk surrounding a hole in a PCB including, for example, Plated Through-Hole (PTH) vias might have pads extending out at each PCB layer. These extended pads can be left used as-is, omitted, or enlarged to modify the via parasitic properties and change the phase of the signal as it propagates through.
Moreover,
One or more embodiments vary the pad stack details of a via in a multi-layer PCB to tune/modify the self-capacitance of the via. As discussed herein, “self-capacitance” of a via generally refers to the electrical charge to which the via can be charged. For example, if a via pad/structure 106 is included in every layer, the self-capacitance will be at its maximum value. This capacitance will decrease the signal velocity factor of the signal as it propagates through the vertical transition, resembling a longer electrical length as compared to a via with only the top and bottom pads present, for example. In an embodiment, the number of via pads/structures 106 may be varied to modify the resulting signal velocity factor, e.g., between a slow, medium, fast, etc. propagation. As discussed herein, a “signal velocity” generally refers to the speed at which a wave carries information and the term “propagation” refers to the time period it takes a wave to carry the information from one end (TX) to another end (RX).
In one embodiment, a set of via pad stack symbols for a given stack-up can be set as “slow_via,” “med_via,” “fast_via,” etc. A Computer Aided Design (CAD) engineer would simply need to alternate between these symbols as (e.g., High Speed Input/Output (HSIO)) signals are routed. Alternatively, a script could be written to automatically alternate between these symbols for a given set of traces (e.g., memory Data Quality (DQ) bits, Universal Serial Bus (USB) differential pairs, Peripheral Component Interconnect express (PCIe) differential pairs, Transmission Control Protocol (TCP) differential pairs, etc.). Further, in at least one embodiment, the phase tuning approach is considered to be dependent primarily on the via parasitics (e.g., introduced via pads/structures 106) and any effects from the other stack-up details are envisioned to be secondary.
As revealed in the zoomed view of the phase delay capable vias shown in
The phase-delay capable vias offer one or more of the following advantages: (1) shorten trace lengths while maintaining a select phase delay for a signal group between host and target devices to reduce insertion loss and/or FEXT; (2) eliminate serpentine routings to free up board real estate for allowing higher density and/or finer pitch ball out on host and target device themselves; (3) allow placement of host and target dies closer to each other to achieve higher component count per square unit of PCB board; and/or (4) tuning of the amount of phase delay on such via(s) and/or optimizing the amount of phase delay for each individual electrical path on a main board and/or silicon package substrates accordingly, e.g., based on platform signal integrity electrical budget needs.
In one or more embodiments, the phase-delay capable vias may be used in Double Data Rate (DDR) memory Dual In-line Memory Module (DIMM) connector to a (e.g., small) chip. The phase-delay capable vias will results in a shorter and/or more dense/cleaner routing between the connector and the chip, and hence it brings the benefits of lower FEXT, lower insertion loss, and/or better impedance control.
One or more components discussed with reference to
As illustrated in
The I/O interface 540 may be coupled to one or more I/O devices 570, e.g., via an interconnect and/or bus such as discussed herein with reference to other figures. I/O device(s) 570 may include one or more of a keyboard, a mouse, a touchpad, a display, an image/video capture device (such as a camera or camcorder/video recorder), a touch screen, a speaker, or the like.
An embodiment of system 600 can include, or be incorporated within a server-based gaming platform, a game console, including a game and media console, a mobile gaming console, a handheld game console, or an online game console. In some embodiments system 600 is a mobile phone, smart phone, tablet computing device or mobile Internet device. Data processing system 600 can also include, couple with, or be integrated within a wearable device, such as a smart watch wearable device, smart eyewear device, augmented reality device, or virtual reality device. In some embodiments, data processing system 600 is a television or set top box device having one or more processors 602 and a graphical interface generated by one or more graphics processors 608.
In some embodiments, the one or more processors 602 each include one or more processor cores 607 to process instructions which, when executed, perform operations for system and user software. In some embodiments, each of the one or more processor cores 607 is configured to process a specific instruction set 609. In some embodiments, instruction set 609 may facilitate Complex Instruction Set Computing (CISC), Reduced Instruction Set Computing (RISC), or computing via a Very Long Instruction Word (VLIW). Multiple processor cores 607 may each process a different instruction set 609, which may include instructions to facilitate the emulation of other instruction sets. Processor core 607 may also include other processing devices, such a Digital Signal Processor (DSP).
In some embodiments, the processor 602 includes cache memory 604. Depending on the architecture, the processor 602 can have a single internal cache or multiple levels of internal cache. In some embodiments, the cache memory is shared among various components of the processor 602. In some embodiments, the processor 602 also uses an external cache (e.g., a Level-3 (L3) cache or Last Level Cache (LLC)) (not shown), which may be shared among processor cores 607 using known cache coherency techniques. A register file 606 is additionally included in processor 602 which may include different types of registers for storing different types of data (e.g., integer registers, floating point registers, status registers, and an instruction pointer register). Some registers may be general-purpose registers, while other registers may be specific to the design of the processor 602.
In some embodiments, processor 602 is coupled to a processor bus 610 to transmit communication signals such as address, data, or control signals between processor 602 and other components in system 600. In one embodiment the system 600 uses an exemplary ‘hub’ system architecture, including a memory controller hub 616 and an Input Output (I/O) controller hub 630. A memory controller hub 616 facilitates communication between a memory device and other components of system 600, while an I/O Controller Hub (ICH) 630 provides connections to I/O devices via a local I/O bus. In one embodiment, the logic of the memory controller hub 616 is integrated within the processor.
Memory device 620 can be a dynamic random access memory (DRAM) device, a static random access memory (SRAM) device, flash memory device, phase-change memory device, or some other memory device having suitable performance to serve as process memory. In one embodiment the memory device 620 can operate as system memory for the system 600, to store data 622 and instructions 621 for use when the one or more processors 602 executes an application or process. Memory controller hub 616 also couples with an optional external graphics processor 612, which may communicate with the one or more graphics processors 608 in processors 602 to perform graphics and media operations.
In some embodiments, ICH 630 enables peripherals to connect to memory device 620 and processor 602 via a high-speed I/O bus. The I/O peripherals include, but are not limited to, an audio controller 646, a firmware interface 628, a wireless transceiver 626 (e.g., Wi-Fi, Bluetooth), a data storage device 624 (e.g., hard disk drive, flash memory, etc.), and a legacy I/O controller 640 for coupling legacy (e.g., Personal System 2 (PS/2)) devices to the system. One or more Universal Serial Bus (USB) controllers 642 connect input devices, such as keyboard and mouse 644 combinations. A network controller 634 may also couple to ICH 630. In some embodiments, a high-performance network controller (not shown) couples to processor bus 610. It will be appreciated that the system 600 shown is exemplary and not limiting, as other types of data processing systems that are differently configured may also be used. For example, the I/O controller hub 630 may be integrated within the one or more processor 602, or the memory controller hub 616 and I/O controller hub 630 may be integrated into a discreet external graphics processor, such as the external graphics processor 612.
The internal cache units 704A to 704N and shared cache units 706 represent a cache memory hierarchy within the processor 700. The cache memory hierarchy may include at least one level of instruction and data cache within each processor core and one or more levels of shared mid-level cache, such as a Level 2 (L2), Level 3 (L3), Level 4 (L4), or other levels of cache, where the highest level of cache before external memory is classified as the LLC. In some embodiments, cache coherency logic maintains coherency between the various cache units 706 and 704A to 704N.
In some embodiments, processor 700 may also include a set of one or more bus controller units 716 and a system agent core 710. The one or more bus controller units 716 manage a set of peripheral buses, such as one or more Peripheral Component Interconnect buses (e.g., PCI, PCI Express). System agent core 710 provides management functionality for the various processor components. In some embodiments, system agent core 710 includes one or more integrated memory controllers 714 to manage access to various external memory devices (not shown).
In some embodiments, one or more of the processor cores 702A to 702N include support for simultaneous multi-threading. In such embodiment, the system agent core 710 includes components for coordinating and operating cores 702A to 702N during multi-threaded processing. System agent core 710 may additionally include a power control unit (PCU), which includes logic and components to regulate the power state of processor cores 702A to 702N and graphics processor 708.
In some embodiments, processor 700 additionally includes graphics processor 708 to execute graphics processing operations. In some embodiments, the graphics processor 708 couples with the set of shared cache units 706, and the system agent core 710, including the one or more integrated memory controllers 714. In some embodiments, a display controller 711 is coupled with the graphics processor 708 to drive graphics processor output to one or more coupled displays. In some embodiments, display controller 711 may be a separate module coupled with the graphics processor via at least one interconnect, or may be integrated within the graphics processor 708 or system agent core 710.
In some embodiments, a ring-based interconnect unit 712 is used to couple the internal components of the processor 700. However, an alternative interconnect unit may be used, such as a point-to-point interconnect, a switched interconnect, or other techniques, including techniques well known in the art. In some embodiments, graphics processor 708 couples with the ring interconnect 712 via an I/O link 713.
The exemplary I/O link 713 represents at least one of multiple varieties of I/O interconnects, including an on package I/O interconnect which facilitates communication between various processor components and a high-performance embedded memory module 718, such as an eDRAM (or embedded DRAM) module. In some embodiments, each of the processor cores 702 to 702N and graphics processor 708 use embedded memory modules 718 as a shared Last Level Cache.
In some embodiments, processor cores 702A to 702N are homogenous cores executing the same instruction set architecture. In another embodiment, processor cores 702A to 702N are heterogeneous in terms of instruction set architecture (ISA), where one or more of processor cores 702A to 702N execute a first instruction set, while at least one of the other cores executes a subset of the first instruction set or a different instruction set. In one embodiment processor cores 702A to 702N are heterogeneous in terms of microarchitecture, where one or more cores having a relatively higher power consumption couple with one or more power cores having a lower power consumption. Additionally, processor 700 can be implemented on one or more chips or as an SoC integrated circuit having the illustrated components, in addition to other components.
The following examples pertain to further embodiments. Example 1 includes an interconnect comprising: a plurality of links, wherein a first set of links from the plurality of links is to communicate signals and a second set of links from the plurality of links is to provide a return path; and one or more links from the first set of links to comprise one or more structures with a larger diameter than a minimum diameter of the one or more links, wherein the larger diameter is to modify an inductance or capacitance of the one or more links to provide a heterogenous phase delay amongst the plurality of links. Example 2 includes the interconnect of example 1, wherein the one or more structures are to be dispersed non-uniformly along at least one of the one or more links. Example 3 includes the interconnect of example 1, wherein the one or more structures are to be dispersed uniformly along at least one of the one or more links. Example 4 includes the interconnect of example 1, wherein the one or more structures are to have a circular shape, a square shape, a rectangular shape, a sawtooth shape, or combinations thereof. Example 5 includes the interconnect of example 1, wherein the one or more structures are to have differing thicknesses.
Example 6 includes the interconnect of example 1, wherein the one or more structures are to be dispersed: within one or more layers of a multi-layer Printed Circuit Board (PCB), at one or more transition points between two adjoining layers of the multi-layer PCB, or combinations thereof. Example 7 includes the interconnect of example 1, wherein at least one of the first set of links or the second set of links comprises a through-hole via or a partial through-hole via. Example 8 includes the interconnect of example 7, wherein partial through-hole via comprises a blind via or buried via. Example 9 includes the interconnect of example 7, wherein the through-hole via is plated with a conductive material. Example 10 includes the interconnect of example 9, wherein the conductive material is one of copper, nickel, and aluminum.
Example 11 includes the interconnect of example 1, further comprising a PCB to mechanically couple the plurality of links, wherein the PCB is to be surface finished with Hot Air Solder Leveling (HASL) finish, lead free HASL finish, or Electroless Nickel Immersion Gold (ENIG) finish. Example 12 includes the interconnect of example 1, wherein the larger diameter is approximately 20% to 30% larger than the minimum diameter of the one or more links. Example 13 includes the interconnect of example 1, wherein the return path comprises a path to ground. Example 14 includes a system comprising: a Printed Circuit Board (PCB) having a plurality of vias; a plurality of links, wherein a first set of links from the plurality of links is to communicate signals and a second set of links from the plurality of links is to provide a return path; and one or more links from the first set of links to comprise one or more structures with a larger diameter than a minimum diameter of the one or more links, wherein the larger diameter is to modify an inductance or capacitance of the one or more links to provide a heterogenous phase delay amongst the plurality of links.
Example 15 includes the system of example 14, wherein the one or more structures are to be dispersed non-uniformly along at least one of the one or more links. Example 16 includes the system of example 14, wherein the one or more structures are to be dispersed uniformly along at least one of the one or more links.
Example 17 includes the system of example 14, wherein the one or more structures are to have a circular shape, a square shape, a rectangular shape, a sawtooth shape, or combinations thereof. Example 18 includes the system of example 14, wherein the one or more structures are to have differing thicknesses. Example 19 includes the system of example 14, wherein the PCB comprises a multi-layer PCB, wherein the one or more structures are to be dispersed: within one or more layers of the multi-layer PCB, at one or more transition points between two adjoining layers of the multi-layer PCB, or combinations thereof. Example 20 includes the system of example 14, wherein at least one of the first set of links or the second set of links comprises one or more of the plurality of vias, wherein each of the plurality of vias comprises a through-hole via or a partial through-hole via. Example 21 includes an apparatus comprising means to perform a method as set forth in any preceding example.
In various embodiments, the operations discussed herein, e.g., with reference to
Additionally, such computer-readable media may be downloaded as a computer program product, wherein the program may be transferred from a remote computer (e.g., a server) to a requesting computer (e.g., a client) by way of data signals provided in a carrier wave or other propagation medium via a communication link (e.g., a bus, a modem, or a network connection).
Reference in the specification to “one embodiment” or “an embodiment” means that a particular feature, structure, and/or characteristic described in connection with the embodiment may be included in at least an implementation. The appearances of the phrase “in one embodiment” in various places in the specification may or may not be all referring to the same embodiment.
Also, in the description and claims, the terms “coupled” and “connected,” along with their derivatives, may be used. In some embodiments, “connected” may be used to indicate that two or more elements are in direct physical or electrical contact with each other. “Coupled” may mean that two or more elements are in direct physical or electrical contact. However, “coupled” may also mean that two or more elements may not be in direct contact with each other, but may still cooperate or interact with each other.
Thus, although embodiments have been described in language specific to structural features and/or methodological acts, it is to be understood that claimed subject matter may not be limited to the specific features or acts described. Rather, the specific features and acts are disclosed as sample forms of implementing the claimed subject matter.