Patent Application
20140049292
1. Field of the Disclosure
The present disclosure generally relates to signaling between integrated circuit packages.
2. Description of the Related Art
Electronic devices often implement multiple integrated circuit (IC) packages disposed at one or more printed circuit boards (PCB) or other inter-device substrates. In many conventional implementations, signaling between the IC packages is conducted via metal traces at one or more layers of the inter-device substrates. This approach has limited signal speeds due to noise introduced by the relatively long metal traces of the inter-device substrates, and is subject to excessive power consumption due to resistive and capacitive parasitics in the package-to-PCB signaling pathways. In an effort to address these issues, some electronic systems employ repeaters to improve end-to-end signal fidelity and thus permit greater signaling speeds. However, the use of repeaters often significantly increases power consumption and implementation costs. Other systems employ active optical cables to improve signal fidelity and speeds. In this approach, electrical/optical converter devices are implemented at the inter-device substrate to convert electrical signals to optical signals at the transmitting side and subsequently convert the optical signals back to electrical signals at the receiving side. However, this solution leads to considerable power consumption as the electrical signals must traverse between the IC packages and the active-optical cables via the inter-device substrates. Moreover, the use of external devices to repeat or translate inter-package signaling often inhibits refinement of the signaling interfaces of the IC packages as they either must remain backwards-compatible with legacy repeaters/active optical cables, or significant investment must be made to design and fabricate revised versions of the IC packages with new signaling interfaces that are compatible with new or revised signaling formats.
The present disclosure may be better understood, and its numerous features and advantages made apparent to those skilled in the art by referencing the accompanying drawings. The use of the same reference symbols in different drawings indicates similar or identical items.
In one embodiment, the connector assembly of the IC package and the corresponding connector assembly of the external transceiver module are configured to provide a “press fit” relationship whereby the connector assemblies form a friction coupling that helps maintain the connector assemblies in position under expected operational conditions. This press fit relation thereby allows the external transceiver module to be removably attachable to the IC package, and thus permits swapping between different external transceiver modules so as to communicate over different transmission mediums. A retention element, such as a pin, clamp, or lever, also may be used to maintain the mechanical attachment between connector assemblies. In one embodiment, the external transceiver module is implemented as one head end of a cable, whereby the transmission medium of the cable can comprise wire conductors or optical waveguides. The other head end of the cable can comprise another external transceiver module that attaches to another IC package, or a conventional cable end to attach to, for example, an active optical cable package or other IC transceiver package. In another embodiment, the transmission medium comprises a wireless medium, such as a radio frequency (RF) or infrared (IR) medium, and thus the external transceiver module can comprise a wireless transceiver module that converts outgoing electrical signaling from the IC package to RF or IR signals, and converts incoming RF or IR signals to electrical signaling for processing by the IC package.
In one embodiment, the electrical signaling interface implemented at the IC package comprises a broadly-compatible electrical signaling interface that is not specific to the transmission medium between the IC packages (and hence referred to herein as “medium independent”). Thus, the external transceiver module is responsible for converting between medium-independent signaling format provided to/from the electrical signaling interface and the medium-dependent signaling format used to communicate signaling over the transmission medium. For example, if the transmission medium comprises wire pairs intended for differential signaling, rather than implement a differential signaling transceiver as the electrical signaling interface of the IC package, the electrical signaling interface instead may implement a single-ended transceiver and the external transceiver module would thus implement circuitry for converting the single-ended format of the signaling from the electrical signaling interface to a differential format appropriate for transmission over the wire pair of the transmission medium. Likewise, the external transceiver module would implement circuitry for converting signaling received from the wire pairs from a differential format to a single-ended format for reception and processing by the IC package. As another example, the signaling format conversion provided by the external transceiver module can include conversion from an electrical signaling format to an optical signaling format and vice versa, conversion from an electrical signaling format to an RF signaling format and vice versa, conversion from an electrical signaling format to an IR signaling format and vice versa, and the like.
By implementing a medium-independent signaling interface at the IC package and implementing a medium-dependent signaling interface at the external transceiver module, the same IC package design can be implemented in any of a variety of signaling environments by selecting a particular external transceiver module suited for the desired transmission medium. To illustrate, the same IC package can be used in both a device that calls for optical signaling between components and a device that calls for wireless signaling between components by selecting and attaching an external transceiver module implementing electrical/optical conversion in the first instance and by selecting and attaching an external transceiver module implementing electrical/wireless conversion in the second instance. Moreover, because the IC package can implement a relatively simple and widely adopted single-ended signaling interface, the IC package can be compatible with new system architectures having signal formats that change and evolve by implementing different or revised external transceiver modules, and thus making it unnecessary to redesign the IC package to accommodate new signal formats.
For ease of illustration, the example embodiments of the present disclosure are described in the context of a full-duplex link (that is, separate transmit and receive paths) inter-package transmission medium. However, the techniques described herein may be implemented in half-duplex (that is, a shared transmit/receive path) or unidirectional (that is, one-way) inter-package communications without departing from the scope of the present disclosure. Accordingly, unless otherwise noted, reference to “transceiver” can include reference to a transmitter, a receiver, or a combination of a transmitter and a receiver. Moreover, these example embodiments are described in a context whereby the bi-directional inter-package transmission medium comprises one upstream channel and one downstream channel. However, these techniques are not limited to this example implementation, but instead may include multiple upstream channels and multiple downstream channels. Moreover, some applications may implement multiple links that can be included in one transceiver, or use separate transceivers for each link. Additionally, one or more upstream channels and one or more downstream channels may share the same physical transmission medium using any of a variety of duplexing techniques, such as time division multiplexing, frequency division multiplexing, and the like.
The inter-device cable 101 includes two transceiver modules 112 and 114 (as cable heads) coupled via a cable body 116. As illustrated by expanded view 118, each of the transceiver modules 112, 114 includes a connector assembly 120 having contact terminals 122 electrically coupled to transceiver circuitry 124. The transceiver circuitry 124, in turn, is coupled to a transmission medium of the cable body 116. The transmission medium, in one embodiment, includes an electrically conductive medium (e.g., metal wires). In another embodiment, the transmission medium includes an optical transmission medium (e.g., optical waveguides). The inter-device cable 101 conducts signaling between the IC package 102 and 104 via the transmission medium of the cable body 116. In one embodiment, the transceiver module proximate to the transmitting IC package receives electrical signaling from the transmitting IC package, uses the transceiver circuitry 124 to convert the received electrical signaling from a medium-independent signaling format to a medium-dependent signaling format appropriate for transmission over the transmission medium of the cable 101, and transmits the converted signaling to the other transceiver module via the transmission medium. At the receiving end, the transceiver module proximate to the receiving IC package converts the converted signaling back to the original signaling format (or other signaling format appropriate for the receiving IC package) and provides the reconverted signaling to the receiving IC package. This process is described in greater detail below.
The IC package 102 includes one or more dies 126 (also referred to as “chips”) disposed at a top surface 128 of a package substrate 130, whereby the one or more dies and at least the top surface 128 of the package substrate 130 are encapsulated or otherwise enclosed by an encapsulating structure 131 (which may include a package lid) to form the IC package 102. Bond pads of integrated circuitry formed at an active surface 132 of the die 126 are coupled to corresponding bond pads at the top surface 128 of the package substrate 130 via intra-device contacts 134 (e.g., C4 bumps, microbumps, solder balls or other solder joints, pins, and the like). In turn, bond pads at the bottom surface 136 of the package substrate 130 are connected to corresponding bond pads of the PCB 106 via inter-device contacts 138. The package substrate 130 further includes metal interconnect structures (metal traces and inter-layer vias) to provide various electrical connections between bond pads of the package substrate 130.
The example depicted in
The IC package 102 further comprises a connector assembly 140 disposed at the top surface 128 of the package substrate 130 and electrically connected to the integrated circuitry of the die 126 via one or more intra-device contacts 134 and one or more metal structures (e.g., metal structures 142 and 144) of the package substrate 130. As illustrated by enlarged view 118, the connector assembly 140 is positioned at, or otherwise accessible via, an aperture 146 at a surface 148 of the IC package 102 and includes contact terminals 150 electrically coupled to an electrical signaling interface 152 of the integrated circuitry of the die 126. In the depicted example, the aperture 146 is disposed at a side surface of the IC package 102 (that is, a surface substantially perpendicular with the surface of the IC package 102 facing the package substrate 130) and aligned with a socket opening or terminal plug of the connector assembly 140. In other embodiments, the connector assembly 140 and the aperture 146 may be disposed at a top surface of the IC package (that is, the surface opposite the surface of the IC package 102 facing the package substrate 130). The connector assembly 140 further includes a housing to mechanically attach the connector assembly 140 to a corresponding housing of the connector assembly 120 such that the contact terminals 150 of the connector assembly 140 are brought into physical and electrical contact with the corresponding contact terminals 122 of the connector assembly 120, thereby electrically coupling the integrated circuitry of the die 126 with the transceiver circuitry 124 of the transceiver module 112.
In at least one embodiment, the connector assemblies 120 and 140 are removably attachable (i.e., “pluggable”) with respect to each other. To this end, the connector assemblies 120 and 140 can be compatibly configured so as to provide a press-fit relationship between the connector assembly 120 and the connector assembly 140. That is, the physical shape and dimensions of the connector assembly 120 and the physical shape and dimensions of the connector assembly 140 are such that the connector assemblies 120 and 140 may be maintained in mechanical and electrical contact through a friction coupling. To illustrate, in the depicted example of
In one embodiment, the external transceiver module 114 and the IC package 104 may be configured in a similar manner, such that the transceiver module 114 “plugs into” the IC package 104 via an aperture in the side or top of the IC package 104. In another embodiment, the IC device 104 comprises a conventional IC package and thus the transceiver module 114 communicates signaling between the cable 101 and the IC package 104 via metal traces of the PCB 108 and the inter-device contacts 138 of the IC package 104.
In conventional implementations, the IC packages 102 and 104 would be either electrically coupled via metal trace paths formed through metal traces in the PCB 106, the PCB 108 and the socket 110, or coupled via an active optical cable having one end disposed at the PCB 106 proximate to the IC package 102 and the other end disposed at the PCB 108 proximate to the IC package 104. Either approach would require electrical signaling to traverse a metal trace of one of the PCBs and traverse an inter-device contact 138 of the corresponding IC package. As such, the PCB may require additional metal layers and the IC packages would require additional inter-device contacts 124 to conduct this signaling, and unnecessary power would be consumed through resistive and capacitive parasitic present in the signal pathways formed by the inter-device contacts 138 and metal traces of the PCBs. However, by providing a connector assembly at a side or top surface of the IC packages 102 and 104, the IC packages 102 and 104 may be coupled to an inter-package transmission medium in a manner that avoids the package substrate-PCB interface, and thus requires fewer package pins and less energy expended per bit transmitted. Moreover, as the cable 101 can implement transceiver circuitry 124 suitable for the transmission medium of the cable body 116, the electrical signal interface 152 can implement a driver/receiver design that is independent of the particular transmission medium. In this way, it may not be necessary to modify the design of the IC packages 102 and 104 to take advantage of a variety of transmission mediums or in response to development of new signal transmission formats or protocols. Rather, under this approach, it is the design of the cable 101 that is adapted or revised in view of advancements in signaling formats or protocols, or it is a particular type of cable selected for use as the cable 101 in view of a particular signaling requirement.
The wireless transceiver module 212 includes one or more antennas (not shown), wireless transceiver circuitry 224, and a connector assembly 220 mechanically and electrically attached to the connector assembly 140 of the IC package 102 so as to electrically connect the electrical signaling interface 152 of the die 126 with the wireless transceiver circuitry 224 of the wireless transceiver module 214. In the depicted example, the wireless transceiver module 212 includes an IC package having inter-device contacts 238 coupled to bond pads of the substrate portion 202, whereby the inter-device contacts 238 can be used to provide supply voltages to the wireless transceiver module 212, conduct signaling between the wireless transceiver module 212 and other components of the electronic device 200, as well as to provide a mechanism for mechanically securing the wireless transceiver module 212. Although
In operation, electrical signaling generated by the electrical signaling interface 152 of the die 126 is provided to the wireless transceiver circuitry 224 of the wireless transceiver 212 via the connector assemblies 140 and 220. The wireless transceiver circuitry 224 converts the electrical signaling to wireless signaling for transmission to the wireless transceiver module 214. Similarly, the wireless transceiver circuitry 224 receives wireless signaling from the wireless transceiver module 214, converts the wireless signaling to electrical signaling, and transmits the resulting electrical signaling to the electrical signaling interface 152 of the die 126 via the connector assemblies 140 and 220. The wireless transceiver circuitry of the wireless transceiver module 214 can be configured to operate in the same manner with respect to the IC package 104 or to operates as a standalone transceiver (e.g., as a wireless display device). The wireless signaling can include radio frequency (RF) signaling, and the wireless transceiver circuitry 224 thus can include, for example, a Bluetooth-compliant transceiver, a ZigBee RF4CE-compliant transceiver, IEEE 802.11-compliant transceiver (e.g., a WiGig 60 Gigaherz transceiver), or an RF transceiver implementing a proprietary RF signal format. Alternatively, the wireless signaling can include infrared (IR) signaling, and the wireless transceiver circuitry 224 thus can include an IR transceiver compatible with an industry-standard or proprietary IR signaling format. An example implementation of the wireless transceiver circuitry 224 is described below with reference to
The die 126 includes integrated circuitry including the electrical signaling interface 152 coupled to signal processing circuitry 804, which generates signals to be transmitted by the electrical signaling interface 152 and which processes signals received from the electrical signaling interface 152. In the depicted example, the electrical signal interface 152 comprises a serial interface comprising a line driver 804 and line receiver 806. The line driver 804 comprises an input coupled to an output of the signal processing circuitry 802 and comprises an output coupled to contact terminal 808 of the connector assembly 140. The line receiver 806 comprises an input coupled to a contact terminal 810 of the connector assembly 140 and an output coupled to an input of the signal processing circuitry 802.
The external transceiver module 112 includes the transceiver circuitry 124 and the connector assembly 120. The connector assembly 120 includes contact terminals 818 and 820, which correspond to contact terminals 808 and 810, respectively, of the connector assembly 140. The transceiver circuitry 124 includes a driver 824 and a receiver 826. The driver 824 includes an input coupled to the contact terminal 818 and an output coupled to a transmission line 828 of the cable body 116. The receiver 826 includes an input coupled to a transmission line 830 of the cable body 116 and an output coupled to the contact terminal 820. In one embodiment, the transmission lines 828 and 830 comprise optical waveguides and thus the driver 824 comprises an electrical-to-optical converter and the receiver 826 comprises an optical-to-electrical converter. In another embodiment, the transmission lines 828 and 830 each comprise a differential wire pair (such as a twisted pair) and thus the driver 824 comprises a differential signal driver and the receiver 826 comprises a differential signal receiver.
The connector assemblies 120 and 140 and the contact terminals 808, 810, 818, and 820 are dimensioned and positioned such that when the connector assemblies 120 and 140 are brought together (that is, the cable 101 is plugged into the IC package 102), the connector assemblies 120 and 140 are mechanically attached through a friction coupling, the contact terminal 808 is brought into physical and electrical contact with the contact terminal 818, and the contact terminal 810 is brought into physical and electrical contact with the contact terminal 820. In this manner, a conductive path is formed between the output of the line driver 804 and the input of the driver 824 and a conductive path is formed between the output of the receiver 826 and the input of the receiver 806. Accordingly, an output signal provided by the signal processing circuitry 802 is driven by the line driver 804 to the driver 824, which converts the output signal into a signal format suitable for the transmission line 828 and drives the converted output signal onto the transmission line 828. Conversely, a signal received over the transmission line 830 is converted by the receiver 826 to a signal format suitable for the line receiver 806, which in turn drives the converted received signal to the signal processing circuitry 802. The transmission lines 828 and 830 may be implemented using commercially available or proprietary electrical cables or optical waveguides.
In one embodiment, the line transmitter 804 and the line receiver 806 of the IC package 102 are medium-independent and the transmitter 824 and the receiver 826 of the external transceiver module 112 are medium-dependent in that the line transmitter 804 transmits signaling and the line receiver 806 receives signaling in a signal format that is independent of the signaling format used for the inter-package transmission medium (e.g., the transmission lines 828 and 830), whereas the transmitter 824 is responsible for converting the signaling to a signal format appropriate for the inter-package transmission medium and the receiver is responsible for converting the signaling from the signal format of the inter-package transmission medium. Thus, to facilitate interoperability with a variety of external transceiver modules and a variety of transmission mediums, in one embodiment the line driver 804 and line receiver 806 implement a relatively simple and relatively easily convertible signaling format, such as a single-ended serial electrical signal format. Thus, the line transmitter 804 can include a single-ended line driver and the line receiver comprises a single-ended line receiver 806. Under this approach, the same IC package can be with various transmission mediums by selecting the appropriate external transceiver module for the transmission medium. Further, in the event that a new or revised signaling format is developed, rather than revising the design of the IC package (which often is an expensive and time-consuming task), the design of the external transceiver module instead may be revised (which often is a less expensive and less-time consuming task).
Conversely, the receiver 826 of the transceiver circuitry 824 comprises an optical-to-electrical converter comprising a photodiode 908 and a transimpedance amplifier (TIA) 910. The photodiode 908 is optically coupled to the optical waveguide 930 and comprises an output to provide a current representative of an optical signal received via the optical waveguide 930. The TIA 910 has an input coupled to the output of the photodiode 908 and an output, whereby the TIA 910 converts the current-based signal output by the photodiode 908 to a voltage-based single-ended signal IN_SE provided to the line receiver 806 (
Conversely, the receiver 826 of the transceiver circuitry 824 comprises a differential-to-single-ended receiver 1006 comprising an input to receive a differential signal from the wire pair 1030, the received differential signal comprising signal components IN and IN_B (IN_B being an inverted or phase shifted representation of IN) and an output, whereby the receiver 1006 converts the received differential signal to a voltage-based single-ended signal IN_SE, which is then provided to the line receiver 806.
In at least one embodiment, the apparatus and techniques described above are implemented in a system comprising one or more integrated circuit (IC) devices (also referred to as integrated circuit packages or microchips), such as the IC packages 102 and 104 and the external transceiver modules 112, 114, 212, and 214. Electronic design automation (EDA) and computer aided design (CAD) software tools may be used in the design and fabrication of these IC devices. These design tools typically are represented as one or more software programs. The one or more software programs comprise code executable by a computer system to manipulate the computer system to operate on code representative of circuitry of one or more IC devices so as to perform at least a portion of a process to design or adapt a manufacturing system to fabricate the circuitry. This code can include instructions, data, or a combination of instructions and data. The software instructions representing a design tool or fabrication tool typically are stored in a computer readable storage medium accessible to the computing system. Likewise, the code representative of one or more phases of the design or fabrication of an IC device may be stored in and accessed from the same computer readable storage medium or a different computer readable storage medium.
A computer readable storage medium may include any storage medium, or combination of storage media, accessible by a computer system during use to provide instructions and/or data to the computer system. Such storage media can include, but is not limited to, optical media (e.g., compact disc (CD), digital versatile disc (DVD), Blu-Ray disc), magnetic media (e.g., floppy disc, magnetic tape, or magnetic hard drive), volatile memory (e.g., random access memory (RAM) or cache), non-volatile memory (e.g., read-only memory (ROM) or Flash memory), or microelectromechanical systems (MEMS)-based storage media. The computer readable storage medium may be embedded in the computing system (e.g., system RAM or ROM), fixedly attached to the computing system (e.g., a magnetic hard drive), removably attached to the computing system (e.g., an optical disc or Universal Serial Bus (USB)-based Flash memory), or coupled to the computer system via a wired or wireless network (e.g., network accessible storage (NAS)).
At block 1202 a functional specification for the IC device is generated. The functional specification (often referred to as a micro architecture specification (MAS)) may be represented by any of a variety of programming languages or modeling languages, including C, C++, SystemC, Simulink, or MATLAB.
At block 1204, the functional specification is used to generate hardware description code representative of the hardware of the IC device. In at least one embodiment, the hardware description code is represented using at least one Hardware Description Language (HDL), which comprises any of a variety of computer languages, specification languages, or modeling languages for the formal description and design of the circuits of the IC device. The generated HDL code typically represents the operation of the circuits of the IC device, the design and organization of the circuits, and tests to verify correct operation of the IC device through simulation. Examples of HDL include Analog HDL (AHDL), Verilog HDL, SystemVerilog HDL, and VHDL. For IC devices implementing synchronized digital circuits, the hardware descriptor code may include register transfer level (RTL) code to provide an abstract representation of the operations of the synchronous digital circuits. For other types of circuitry, the hardware descriptor code may include behavior-level code to provide an abstract representation of the circuitry's operation. The HDL model represented by the hardware description code typically is subjected to one or more rounds of simulation and debugging to pass design verification.
After verifying the design represented by the hardware description code, at block 1206 a synthesis tool is used to synthesize the hardware description code to generate code representing or defining an initial physical implementation of the circuitry of the IC device. In one embodiment, the synthesis tool generates one or more netlists comprising circuit device instances (e.g., gates, transistors, resistors, capacitors, inductors, diodes, etc.) and the nets, or connections, between the circuit device instances. Alternatively, all or a portion of a netlist can be generated manually without the use of a synthesis tool. As with the hardware description code, the netlists may be subjected to one or more test and verification processes before a final set of one or more netlists is generated.
Alternatively, a schematic editor tool can be used to draft a schematic of circuitry of the IC device and a schematic capture tool then may be used to capture the resulting circuit diagram and to generate one or more netlists (stored on a computer readable media) representing the components and connectivity of the circuit diagram. The captured circuit diagram may then be subjected to one or more rounds of simulation for testing and verification.
At block 1208, one or more EDA tools use the netlists produced at block 1206 to generate code representing the physical layout of the circuitry of the IC device. This process can include, for example, a placement tool using the netlists to determine or fix the location of each element of the circuitry of the IC device. Further, a routing tool builds on the placement process to add and route the wires needed to connect the circuit elements in accordance with the netlist(s). The resulting code represents a three-dimensional model of the IC device. The code may be represented in a database file format, such as, for example, the Graphic Database System II (GDSII) format. Data in this format typically represents geometric shapes, text labels, and other information about the circuit layout in hierarchical form.
At block 1210, the physical layout code (e.g., GDSII code) is provided to a manufacturing facility, which uses the physical layout code to configure or otherwise adapt fabrication tools of the manufacturing facility (e.g., through mask works) to fabricate the IC device. That is, the physical layout code may be programmed into one or more computer systems, which may then control, in whole or part, the operation of the tools of the manufacturing facility or the manufacturing operations performed therein.
Note that not all of the activities or elements described above in the general description are required, that a portion of a specific activity or device may not be required, and that one or more further activities may be performed, or elements included, in addition to those described. Still further, the order in which activities are listed are not necessarily the order in which they are performed.
Also, the concepts have been described with reference to specific embodiments. However, one of ordinary skill in the art appreciates that various modifications and changes can be made without departing from the scope of the present disclosure as set forth in the claims below. Accordingly, the specification and figures are to be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope of the present disclosure.
Benefits, other advantages, and solutions to problems have been described above with regard to specific embodiments. However, the benefits, advantages, solutions to problems, and any feature(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential feature of any or all the claims.
