Patent Description:
As optical systems become more compact and interconnected, heat management of the optical systems has become increasingly important. Ineffective heat management may damage circuits in the optical systems. <CIT> discloses a heat spreader for a caged electrical connector assembly. <CIT> discloses an optical module including a housing, an optical subassembly, a support and a thermal sheet. Heat generated in the optical sub-assembly is transferred to leg portions of the support, to a bridge of the support and to the thermal sheet. <CIT> discloses an interface card cooling using heat pipes. <CIT> discloses a fiber optic transceiver with a heat dissipating structure.

This disclosure describes systems, methods, devices, and other implementations for improving heat transfer in optical transceivers.

An optical transceiver device may include various circuit regions that can generate heat, which, if not managed properly, may cause damage to the optical transceiver device. This disclosure describes a heat transfer structure that complements existing heat transfer devices such as fin structures and heat sinks and thereby may improve heat transfer capabilities in optical transceiver devices and systems. The heat transfer structure can connect one or more circuit regions to the heat sink while bypassing circuit regions that may impede the transfer of heat from the one or more circuit regions. The heat transfer structure may directly contact the one or more circuit regions and the heat sink and may include an opening to avoid contact with the circuit regions to be bypassed.

According to the invention a device for improving heat transfer according to claim <NUM> is provided.

The heat transfer mechanism described in this disclosure can be advantageous in some implementations to provide an affordable, cost-effective solution to optimizing heat management in optical transceiver devices and systems. A heat transport structure can be configured based on the design of an optical transceiver device and can be designed to connect one or more regions of the optical transceiver device to a heat-transferring device such as a heat sink and to circumvent regions of the optical transceiver device that may impede heat transfer.

Optical transceiver devices can be used to connect electronic devices like network servers or switches to data transportation structures such as copper or fiber cables. As <NUM> technology continues to evolve and the market demands greater storage capabilities and higher speeds, it has become increasingly important that optical transceiver devices are designed to support faster speeds and larger data transfers while managing density, bandwidth, and thermal issues.

To facilitate thermal management, optical transceiver devices may be coupled to a heat sink to provide relief from excess heat in regions of the optical transceiver devices where circuits are deployed. However, this method of heat dissipation through the use of a heat sink may present several limitations. For example, the amount of heat dissipated may depend on ambient temperature and airflow. In addition, for optical transceiver devices with multiple regions of integrated circuits (ICs), heat generated from one region may spread to another region, thereby increasing the amount of heat in the other region. When heat spreads from one IC region to another, the heat dissipation effectiveness of the heat sink decreases considerably, leaving the optical transceiver device vulnerable to damage from excessive heat.

To address at least some of the foregoing issues, a heat transport structure is incorporated into an optical transceiver system such that heat is transferred from one IC region of an optical transceiver device to the heat sink without being affected by other IC regions of the optical transceiver device. The heat transport structure can be disposed on a housing of the optical transceiver device and can include at least two contact regions. One of these contact regions is in contact with, or coupled to, the heat sink, and the other contact region is in contact with, or coupled to, an IC region from which heat is to be transferred. The heat transport structure also may include one or more openings corresponding to other IC regions from which the heat transport structure is not configured to transfer heat. In this manner, heat can be transferred effectively from the desired IC region to the heat sink without interference from other IC chips in the optical transceiver device.

Additional details and benefits of the heat transferring mechanism used in optical transceiver systems and devices are described below with reference to the figures.

<FIG> illustrates an example of an optical transceiver device <NUM>. The optical transceiver device <NUM> includes a transmitter and a receiver (TROSA <NUM> shown in <FIG>). The transmitter in the optical transceiver device <NUM> may generate an electrical signal at a certain code rate to drive a semiconductor laser (LD) or an optical emitting diode (LED) to emit a modulated optical signal of a corresponding rate through a medium such as a fiber optic cable. The receiver in the optical transceiver device <NUM> is operable to receive an optical signal input at a certain code rate, and to convert the optical signal to an electrical signal using, for example, a photodetecting diode for further processing.

In general, the optical transceiver device <NUM> may be configured to transport data between a data-transferring component such as, e.g., a copper or fiber optic cable, and an electronic device such as, e.g., a server or network switch. One end of the optical transceiver device <NUM> can be plugged into a port of the electronic device, and another end connected to the data-transferring component. Because the optical transceiver device <NUM> operates, in part, as an interface between a data-transferring component and an electronic device, an optical transceiver also may be referred to as a network interface device.

In general, an optical transceiver device <NUM> can be implemented in various shapes, sizes, and configurations. In some implementations, the optical transceiver device <NUM> may be a small form-factor pluggable (SFP) device, which is a compact, hot-pluggable network interface module used for both telecommunication and data communications applications. An SFP interface on networking hardware is a modular (plug-and-play) slot for a media-specific transceiver in order to connect a fiber-optic cable or sometimes a copper cable.

Examples of SFP devices include, but are not limited to, a Quad Small Form-factor Pluggable (QSFP) device and a QSFP-DD (QSFP-Double Density), only the latter being encompassed by the claimed invention. QSFPs include additional lanes relative to other SFPs to support four times faster speeds (e.g., up to <NUM> Gbit/s) than corresponding SFPs. QSFP-DDs are similar to QSFP but include an additional row of contacts providing for an eight lane electrical interface. QSFP-DD devices can offer double (e.g., up to <NUM> Gbit/s) the speed of QSFPs. With such high data transfer speeds and dense circuitry supporting the data transfer within the optical transceiver, effective thermal management is desired to prevent overheating, as explained above. This disclosure describes optical transceivers with the capability to dissipate heat effectively through the use of a heat transport structure.

In <FIG>, the optical transceiver device <NUM> includes a cable end <NUM>, a pluggable end <NUM>, a shell <NUM>, fin structures <NUM>, a first circuit region <NUM>, and a second circuit region <NUM>. The cable end <NUM> is connected to the data-transferring component such as, e.g., a copper or fiber optic cable. The cable end <NUM> may include pads, pin connectors, and/or one or more interfaces to facilitate the connection with the data-transferring component. The pluggable end <NUM> is configured to be inserted into a cage (not shown in <FIG>). The pluggable end <NUM> may include extensions or fingers with mechanical and electrical interfaces configured to be plugged into the cage and coupled to one or more components of the cage.

Housing or shell <NUM> provides the external structure or skeleton for the optical transceiver device <NUM> and provides protection to components within the optical transceiver device <NUM> from external forces and elements. Shell <NUM> extends from the cable end <NUM> to the pluggable end <NUM> and accommodates the internal components of the optical transceiver device <NUM>. In general, the shell may be made of any suitable material such as, e.g., aluminum, zinc, or a combination thereof, that can withstand environmental and thermal fluctuations and provide structural support to internal components of the optical transceiver device <NUM>.

Among the various internal sections of the optical transceiver device <NUM> are the first circuit region <NUM> and the second circuit region <NUM>. The first circuit region <NUM> and second circuit region <NUM> may include various types of integrated chips (ICs), Application-Specific Integrated Circuits (ASICs), and electronic circuits such as, e.g., controllers, processors such as digital signal processors (DSPs), analog-to-digital converters, digital-to-analog converters, amplifiers, storage devices, filters, and/or photodiodes, and according to the claimed invention the second circuit region comprises a digital signal processing circuit. One or more circuits connected to the TROSA may be implemented in the first circuit region <NUM>. The second circuit region <NUM> is located between the first circuit region <NUM> and the pluggable end <NUM>.

The optical transceiver device <NUM> also may include one or more components to facilitate heat management of the optical transceiver. For example, the optical transceiver device <NUM> may include fin structures <NUM> to assist in thermal dissipation of the heat load from the first circuit region <NUM> or TROSA located beneath the fin structures <NUM>. In some implementations, the dimensions (e.g., depth) of the fin structures <NUM> may conform to the specifications set forth by the Multi-Source Agreement (MSA) issued by the industry-recognized Small Form Factor Committee.

The amount of heat dissipated by the fin structures <NUM> may depend, at least in part, on the heat generated by the first circuit region <NUM>, the airflow, the ambient temperature, and the depth of the fin structures <NUM>. At times, the fin structures <NUM> may not be sufficient to transfer heat away from the first circuit region <NUM>. When this situation occurs, components within the optical transceiver device <NUM> may become structurally and/or functionally damaged. To further facilitate heat management and address the above-noted issue, the optical transceiver device <NUM> may be coupled to a heat-transferring device such as, e.g., a heat sink, to transfer heat away from one or more circuit regions of the optical transceiver.

<FIG> depict an example coupling of an optical transceiver device <NUM> and a heat-transferring device <NUM> in an optical transceiver system. <FIG> depicts the optical transceiver device <NUM> described with respect to <FIG>. To couple the optical transceiver device <NUM> to the heat-transferring device <NUM>, a cage <NUM> may be used.

<FIG> depicts an example of the cage <NUM>, which may include, among various other components, a housing or shell <NUM>, a pluggable end <NUM>, and an opening <NUM>. Shell <NUM> provides the external structure or skeleton to provide structural support and protection to components within the shell <NUM>. The components within the shell <NUM> provide an interface between the optical transceiver device <NUM> and the heat-transferring device <NUM>. In some implementations, the design, including thermal and mechanical specifications, of the shell <NUM> may comply with the specifications of the MSA.

The pluggable end <NUM> of the cage <NUM> is configured to be engaged with the optical transceiver device <NUM>. In particular, the pluggable end <NUM> of the cage <NUM> may have a first opening to allow the pluggable end <NUM> of the optical transceiver device <NUM> to be inserted into the cage <NUM>, as shown in <FIG>. The pluggable end <NUM>, and more generally the cage <NUM>, may include one or more locking mechanisms such as, e.g., fasteners, that provide resistance to the decoupling of the cage <NUM> and the optical transceiver device <NUM> once the cage <NUM> and the optical transceiver device <NUM> are coupled together.

Cage <NUM> may also include a second opening <NUM> that exposes a cavity within the cage <NUM>. The cavity accommodates the optical transceiver device <NUM> when inserted into and engaged with the cage <NUM>. When the optical transceiver device <NUM> is inserted into the cage <NUM>, the second opening <NUM> exposes a top surface <NUM> of the second circuit region <NUM> of the optical transceiver device <NUM>, as shown in <FIG>.

In <FIG>, a heat-transferring device <NUM> is engaged with the cage <NUM> and the optical transceiver device <NUM>. In general, the heat-transferring device <NUM> may refer to a passive electronic component configured to transfer heat generated by an electronic or a mechanical device to another medium, e.g., air, liquid. In some implementations, the heat-transferring device <NUM> may be a heat sink.

The heat-transferring device <NUM> may be mechanically and electrically connected to the cage <NUM> and/or the optical transceiver device <NUM> in various configurations. In the implementation depicted in <FIG>, a spring-loaded heat-transferring device <NUM> is disposed on top of the cage <NUM> and the optical transceiver device <NUM>. The cage <NUM> provides structural support so that the heat-transferring device <NUM> can engage with the optical transceiver device <NUM>.

Furthermore, as noted above, the second opening <NUM> in cage <NUM> exposes portions of the optical transceiver device <NUM> when inserted into the cage <NUM>. When the heat-transferring device <NUM> is disposed on the cage <NUM>, the heat-transferring device <NUM> may be thermally coupled, directly or indirectly, to the second circuit region <NUM> through the top surface <NUM> of the optical transceiver device <NUM>. Through this coupling, heat may be transferred away from the second circuit region <NUM> and towards the heat-transferring device <NUM>. The heat-transferring device <NUM> is configured to transfer heat from the second circuit region <NUM> to the ambient environment, e.g., air, thereby allowing the temperatures of the second circuit region <NUM> to be managed (e.g., cooled). This heat-transferring device <NUM> may include one or more fans to direct and control airflow in a particular direction, e.g., from the cable end <NUM> of the optical transceiver device <NUM> to an end of the heat-transferring device <NUM> facing away from the optical transceiver device <NUM>.

In some implementations, additional cooling capacity and elements may be included in the heat-transferring device <NUM> to provide additional heat relief to the optical transceiver device <NUM>. In some implementations, the cage <NUM> and heat-transferring device <NUM> are assembled into a rack box.

As explained above with respect to <FIG> and <FIG>, the optical transceiver device <NUM> may include fin structures <NUM> or may be coupled to heat-transferring devices, such as device <NUM>, to manage heat. However, as the density of integrated chips and circuits increases and the demands for greater bandwidth and speed in optical transceivers increases, fin structure <NUM> and/or heat-transferring device <NUM> may not provide optimum thermal performance or the most effective heat transfer solutions.

For example, referring to <FIG>, fin structure <NUM> has limited surface contact area with first circuit region <NUM> and may be inadequate to dissipate the heat generated by the first circuit region <NUM>. Heat-transferring device <NUM> is not as effective in transferring heat from the first circuit region <NUM>, because, in some instances, heat generated by the second circuit region <NUM> can be several (e.g., two to three) times that of the heat generated by the first circuit region <NUM>, thereby negating the ability of the heat-transferring device <NUM> to cool the first circuit region <NUM>. This issue may occur, for example, in optical transceiver device <NUM> configurations in which the second circuit region <NUM> has one or more digital signal processors or ASICs operating, which can generate significant amounts of heat. More generally, this issue in transferring heat may arise when heat from a source region is to be transferred to the heat-transferring device <NUM>, but an intervening region (e.g., the second circuit region <NUM> with a running DSP) in the path between the source region and the heat-transferring device <NUM> generates more heat than surrounding regions and/or the source region.

In addition, in the past, optical transceivers generally have consumed smaller amounts of power so that additional heat sinking to remove excess heat was not required. In the newer and upcoming generation of optical transceivers, greater power, e.g., more than <NUM> Watts of power, may be used and may entail additional heat sinking, moving air, and moving or transferring heat from one location to another.

To address the issue of intervening elements or interferences compromising heat transfer in optical transceivers and to provide additional mechanisms for performing heat transfer, a heat transport structure <NUM>, as shown in <FIG>, is implemented in the optical transceiver device <NUM>. The optical transceiver device <NUM> in <FIG> is similar to the optical transceiver device <NUM> shown in <FIG> but does not show the fin structures <NUM> and TROSA. The heat transport structure <NUM> may be made of a highly conductive structure such as, e.g., a graphite tape, heat piping, or a vapor chamber. The heat transport structure <NUM> may include one or more of each of the graphite tape, heat piping, and a vapor chamber, or any combination of the three, and according to the claimed invention it comprises a graphite tape. In some implementations, the heat transport structure <NUM> may include a thermally conductive structure or an anisotropic conductive material such that conductivity can be directed in a particular direction. For example, the conductivity can be directed from a desired source circuit region to the heat-transferring device <NUM>.

The heat transport structure <NUM> may be configured in various different suitable ways depending on the design of the optical transceiver device <NUM> and the region(s) of the optical transceiver device <NUM> from which heat relief is desired. For illustrative purposes, the following examples describe implementations in which heat is to be transferred from the first circuit region <NUM> of optical transceiver device <NUM> to the heat-transferring device <NUM>.

<FIG> illustrates one example of a heat transport structure <NUM> being disposed on the optical transceiver device <NUM> to facilitate with heat management of the optical transceiver device <NUM>. The heat transport structure <NUM> provides a path bypassing the second circuit region <NUM> and allowing heat to be transferred from the first circuit region <NUM>, around the second circuit region <NUM>, and to the heat-transferring device <NUM>. The heat transport structure <NUM> may include one or more plates connected to each other to form an integrated structure. In particular, the heat transport structure <NUM> includes a first extension plate <NUM>, a second extension plate <NUM>, and sidewalls 340A, 340B. The heat transport structure <NUM> also includes an opening <NUM> forming a gap in the heat transport structure <NUM>.

As shown in <FIG> and <FIG>, a top surface <NUM> of the first circuit region <NUM> is located closer to the cable end <NUM> of the optical transceiver device <NUM>. The second circuit region <NUM> and top surface <NUM> thereof are located between the first circuit region <NUM> and the pluggable end <NUM> that is coupled to the heat-transferring device <NUM>. The optical transceiver device <NUM> may also include additional surface area <NUM> that is not located directly above second circuit region <NUM> but may be coupled to the heat-transferring device <NUM> to provide additional heat transfer to the heat-transferring device <NUM>.

The heat transport structure <NUM> is disposed on the optical transceiver device <NUM> to optimize heat transfer from the first circuit region <NUM> to the heat-transferring device <NUM>. To accomplish this, the first extension plate <NUM> of the heat transport structure <NUM> may be disposed above and in parallel to the horizontal top surface <NUM> of the first circuit region <NUM> while extending towards the cable end <NUM> of the optical transceiver device <NUM>. The first extension plate <NUM> may be directly or indirectly coupled to the first circuit region <NUM>. For example, the first extension plate <NUM> may directly contact a conductive circuit element such as a wire, heat pipe, or metal contact of the first circuit region <NUM> so that heat from the first circuit region <NUM> may transfer to the first extension plate <NUM>. A compressive force may be applied to the first extension plate <NUM> to ensure strong direct contact between the first circuit region <NUM> and the first extension plate <NUM>. The direct contact enables heat from the first circuit region <NUM> to transfer to the first extension plate <NUM> thereby resulting in a reduction of heat in the first circuit region <NUM>. The first extension plate <NUM> may also be connected to TROSA <NUM> (described further with respect to <FIG>) through application of the compressive force.

The sidewalls 340A, 340B are structures that extend from at least a portion of the first extension plate <NUM> to at least a portion of the second extension plate <NUM>. The sidewalls 340A, 340B are vertical structures configured to fit along the sidewalls of the optical transceiver device <NUM>. One or more curved structures may be used to connect the sidewalls 340A, 340B to horizontal portions of the optical transceiver device <NUM> such as, e.g., the first extension plate <NUM> or the second extension plate <NUM>. Accordingly, the sidewalls 340A, 340B may include angles and turns parallel to the angles and turns of the sidewalls of the optical transceiver device <NUM>.

Sidewall 340A is separated from sidewall 340B by a width of the first extension plate <NUM> or the second extension plate <NUM>. The width may be slightly less than a width of the optical transceiver device <NUM> to enable the heat transport structure <NUM> to fit on a surface of the optical transceiver device <NUM> between the sidewalls of the optical transceiver device <NUM>.

The heat transport structure <NUM> also includes an opening <NUM>, which is formed between the two sidewalls 340A, 340B and between the first extension plate <NUM> and the second extension plate <NUM>. In general, the heat transport structure <NUM> may include one or more openings (including opening <NUM>) that correspond to regions of the optical transceiver device <NUM> from which heat is not desired to be transferred to the heat transport structure <NUM>. Because of such openings, there is no contact between the heat transport structure <NUM> and any such region of the optical transceiver device <NUM> from which heat is not desired to be transferred.

In the example shown in <FIG>, the heat transport structure <NUM> is aligned and placed onto the optical transceiver device <NUM> such that the opening <NUM> is directly above the second opening <NUM> and the top surface <NUM> of the second circuit region <NUM>. Due to the opening <NUM>, the heat transport structure <NUM> does not contact the second circuit region <NUM>, and heat is not thermally conducted from the second circuit region <NUM> through the heat transport structure <NUM>. Instead, the sidewalls 340A, 340B stretch along the surface <NUM> of the second circuit region <NUM> without touching the surface <NUM> and provide a conductive path from the first extension plate <NUM> to the second extension plate <NUM> without any thermal interference from the second circuit region <NUM>.

The second extension plate <NUM> extends towards the pluggable end <NUM> of the optical transceiver device <NUM>. The second extension plate <NUM> is disposed above and in parallel to the horizontal additional surface area <NUM> of the optical transceiver device <NUM> and below the heat-transferring device <NUM>. In some implementations, the bottom surface of the second extension plate <NUM> is directly in contact with the additional surface area <NUM> and the top surface of the second extension plate <NUM> is directly in contact with the heat-transferring device <NUM>. By virtue of the contact with the heat-transferring device <NUM>, the second extension plate <NUM> may enable heat to be transferred from the first extension plate <NUM> to the heat-transferring device <NUM>. In addition, the second extension plate <NUM> may also facilitate heat transfer from other regions of the optical transceiver device <NUM> through the additional area <NUM>.

In some implementations, the second extension plate <NUM> and the first extension plate <NUM> may be disposed at different horizontal planes or elevation levels from each other. In general, the elevation levels may be determined by the design of the optical transceiver device <NUM> such that the heat transport structure <NUM> can be a placed on a top surface of the optical transceiver device <NUM> and aligned to expose the top surface <NUM> of the second circuit region <NUM>, the top surface <NUM> of the first circuit region <NUM>, and the additional surface area <NUM>. In the example shown in <FIG>, the second extension plate <NUM> is formed at a height lower than the height of the first extension plate <NUM>.

Referring to <FIG>, in some implementations, a clamp <NUM> may additionally be disposed on the second extension plate <NUM>. <FIG> depict an optical transceiver device <NUM> like the optical transceiver device <NUM> of <FIG> but additionally includes the TROSA <NUM>, clamp <NUM>, and mounting screws <NUM>. <FIG> depicts an exploded view, and <FIG> depicts a view of the optical transceiver device <NUM> as an integrated device.

The heat transport structure <NUM> may be disposed above the shell <NUM> of the optical transceiver device <NUM> as described above with respect to <FIG>. Clamp <NUM> may provide an additional mechanism to secure or clamp the heat transport structure <NUM> to the optical transceiver device <NUM>. Clamp <NUM> may be disposed directly on the second extension plate <NUM> and beneath the heat-transferring device <NUM>. In this manner, clamp <NUM> can provide a compressive force that enables a strong contact between the heat transport structure <NUM>, the additional surface area <NUM>, and the heat-transferring device <NUM>.

In some implementations, clamp <NUM> may be a conductive block configured to provide mechanical latching to the optical transceiver device <NUM>. For example, the clamp <NUM> may be an aluminum block. In general, the clamp <NUM> may be formed of any suitable thermally conductive material. Various suitable mounting screws <NUM> may also be used. In some cases, the mounting screws <NUM> may be screwed in from a bottom side of shell <NUM>, and, in some cases, the mounting screws <NUM> may be screwed in from a top side of shell <NUM>.

As explained above, TROSA <NUM> may include the receiver and transmitter of the optical transceiver device <NUM>. The TROSA <NUM> may be electrically connected to the first circuit region <NUM>. The TROSA <NUM> is disposed above the first contact region <NUM> with the heat transport structure <NUM> interposed between the TROSA <NUM> and the first contact region <NUM>. Although not shown in <FIG>, additional fin structures may be disposed above TROSA <NUM>, as shown in <FIG>, to facilitate with heat management of the optical transceiver device <NUM>.

While this specification contains many specifics, these should not be construed as limitations on the scope of the disclosure or of what may be claimed, but rather as descriptions of features specific to particular implementations.

Terms used herein and in the appended claims (e.g., bodies of the appended claims) are generally intended as "open" terms (e.g., the term "including" should be interpreted as "including, but not limited to," the term "having" should be interpreted as "having at least," the term "includes" should be interpreted as "includes, but is not limited to," etc.).

Additionally, if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the phrases "at least one" and "one or more" to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles "a" or "an" limits any particular claim containing such introduced claim recitation to implementations containing only one such recitation, even when the same claim includes the introductory phrases "one or more" or "at least one" and indefinite articles such as "a" or "an" (e.g., "a" and/or "an" should be interpreted to mean "at least one" or "one or more"); the same holds true for the use of definite articles used to introduce claim recitations.

In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should be interpreted to mean at least the recited number (e.g., the bare recitation of "two recitations," without other modifiers, means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to "at least one of A, B, and C, etc." or "one or more of A, B, and C, etc." is used, in general such a construction is intended to include A alone, B alone, C alone, A and B together, A and C together, B and C together, or A, B, and C together. The term "and/or" is also intended to be construed in this manner.

Claim 1:
A device (<NUM>) comprising:
a first circuit region (<NUM>) proximate to a first end (<NUM>) of the device;
a second circuit region (<NUM>) proximate to a second end (<NUM>) of the device that is configured to be engaged with a heat-transferring device (<NUM>); and a thermally conductive structure (<NUM>) configured to be coupled to the first circuit region (<NUM>) and the heat-transferring device (<NUM>) and, in response to the device (<NUM>) being engaged to the heat-transferring device (<NUM>), to transfer heat from the first circuit region (<NUM>) to the heat-transferring device (<NUM>) without transferring heat to and from the second circuit region (<NUM>), wherein:
the second end (<NUM>) is located on a side of the device (<NUM>) that is on an opposite side to a side where the first end (<NUM>) is located;
the second circuit region (<NUM>) comprises a digital signal processing circuit;
the thermally conductive structure (<NUM>) comprises a graphite tape;
the heat-transferring device (<NUM>) comprises a heat sink; and
the device (<NUM>) comprises a quad small form factor pluggable double density device.