# US 7,613,026 B2 · Apparatus and methods for optically-coupled memory systems > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,613,026 B2 - Document ID: US7613026B2 - Status: Granted - Kind: B2 - Application number: 12/074,575 - Filed: 2008-03-04 - Published: 2008-07-03 - Granted: 2009-11-03 - Earliest claimed: 2003-01-23 - Assignees: Micron Technology, Inc. - Inventors: Terry R. Lee; Kevin J. Ryan - Web page: https://patentgrep.com/patent/US7613026B2 ## CPC - G11C 7/1054: {Optical output buffers} - G11C 7/1051: {Data output circuits, e.g. read-out amplifiers, data output buffers, data output registers, data output level conversion circuits} - G11C 7/1078: {Data input circuits, e.g. write amplifiers, data input buffers, data input registers, data input level conversion circuits} - G11C 7/1081: {Optical input buffers} - G11C: STATIC STORES (semiconductor memory devices H10B) ## Abstract Optically-coupled memory systems are disclosed. In one embodiment, a system memory includes a carrier substrate, and a controller attached to the carrier substrate and operable to transmit and receive optical signals, and first and second memory modules. The module substrate of the first memory module has an aperture formed therein, the aperture being operable to provide an optical path for optical signals between the controller and an optical transmitter/receiver unit of the second memory module. Thus, the system memory provides the advantages of “free space” optical connection in a compact arrangement of memory modules. In an alternate embodiment, the first memory module includes a beam splitter attached to the module substrate proximate the aperture. In another embodiment, the first and second memory modules are staged on the carrier substrate to provide an unobstructed path for optical signals. In another embodiment, the optical transmitter/receiver unit projects outwardly from the module substrate to provide an unobstructed path for optical signals. ## Claims ### Claim 1 A method of operating a system memory, comprising: providing first and second memory modules having longitudinal axes in an approximately parallel arrangement on a carrier substrate, and a controller spaced apart from the first memory module along a direction opposite from the second memory module and orthogonal to the longitudinal axes, the second memory module having an optical transmitter/receiver unit operatively coupled to a memory device thereof, the first and second memory modules being staged on a carrier substrate such that the second memory module is offset from the first memory module along the longitudinal axis of the second memory module by an amount sufficient to provide a first optical path for optical signals between the controller and the optical transmitter/receiver unit of the second memory module; projecting a first optical signal along the first optical path to the optical transmitter/receiver unit of the second memory module; receiving the first optical signal; determining a memory address corresponding to the first optical signal; and accessing a data value from the corresponding memory address of the memory device. ### Claim 2 (depends on 1) The method of claim 1 wherein determining a memory address corresponding to the first optical signal comprises converting the first optical signal to an electrical signal. ### Claim 3 (depends on 1) The method of claim 1, further comprising: determining a responsive optical signal corresponding to the data value from the corresponding memory address; and projecting the responsive optical signal back along the first optical path. ### Claim 4 (depends on 3) The method of claim 3 wherein determining a responsive optical signal corresponding to the data value comprises converting an electrical signal corresponding to the data value to the responsive optical signal. ### Claim 5 (depends on 1) The method of claim 1 wherein providing a first memory module comprises providing a first memory module having an optical transmitter/receiver unit operatively coupled to a memory device thereof. ### Claim 6 (depends on 5) The method of claim 5, further comprising reflecting a portion of the first optical signal to the optical transmitter/receiver unit of the first memory module. ### Claim 7 (depends on 5) The method of claim 5, further comprising projecting a second optical signal to the optical transmitter/receiver unit of the first memory module. ### Claim 8 (depends on 7) The method of claim 7 wherein the first and second optical signals are projected from a common communication unit on a controller. ### Claim 9 (depends on 7) The method of claim 7 wherein the first and second optical signals are projected from first and second communication units on a controller, respectively. ### Claim 10 A system memory, comprising: a carrier substrate; a controller attached to the carrier substrate to transmit and receive optical signals; a first memory module attached to the carrier substrate proximate the controller, the first memory module including a first module substrate and a first memory device attached to the first module substrate; and a second memory module attached to the carrier substrate proximate the first memory module and opposite from the controller, the second memory module including a second module substrate, a second memory device attached to the second module substrate, and an optical transmitter/receiver unit operatively coupled to the second memory device, the first and second memory modules being staged on the carrier substrate such that the second memory module is offset from the first memory module by an amount sufficient to provide an unobstructed path for optical signals between the controller and the optical transmitter/receiver unit of the second memory module. ### Claim 11 (depends on 10) The system memory of claim 10 wherein the first memory module includes an optical transmitter/receiver unit operatively coupled to the first memory device, and wherein the controller includes a first communication unit operable to communicate optical signals to the optical transmitter/receiver unit of the first memory module, and a second communication unit operable to communicate optical signals to the optical transmitter/receiver unit of the second memory module. ### Claim 12 (depends on 10) The system memory of claim 10 wherein the first memory module includes an optical transmitter/receiver unit operatively coupled to the first memory device, and wherein the controller includes a communication unit operable to communicate optical signals to the optical transmitter/receiver units of both the first and second memory modules. ### Claim 13 (depends on 10) The system memory of claim 10, further comprising a third memory module attached to the carrier substrate and positioned proximate the second memory module opposite from the controller, the third memory module including a third module substrate, a third memory device attached to the third module substrate, and an optical transmitter/receiver unit operatively coupled to the third memory device, the first, second, and third memory modules being staged on the carrier substrate such that the third memory module is offset from the first and second memory modules by an amount sufficient to provide a second unobstructed path for optical signals between the controller and the optical transmitter/receiver unit of the third memory module. ### Claim 14 (depends on 10) The system memory of claim 10 wherein the controller includes first and second communication units operable to communicate optical signals to the optical transmitter/receiver units of the first and second memory modules, respectively. ### Claim 15 (depends on 10) The system memory of claim 10 wherein the controller includes a communication unit operable to communicate optical signals to the optical transmitter/receiver units of the first and second memory modules. ### Claim 16 (depends on 13) The system memory of claim 13 wherein the first, second, and third memory modules are substantially parallel, the second memory module being offset from the first memory module along a longitudinal axis of the second memory module by an amount sufficient to provide the unobstructed path, and the third memory module being offset from the second memory module along a longitudinal axis of the third memory module by an amount sufficient to provide the second unobstructed path. ### Claim 17 A computer system, comprising: a central processing unit; a system memory; and a bus bridge coupled to the central processing unit and the system memory and operable to allow communication between the central processing unit and the system memory, wherein the system memory comprises: a carrier substrate; a controller attached to the carrier substrate and operable to transfer data signals between the system memory and the central processing unit via the bus bridge, the controller further being operable to transmit and receive optical signals; a first memory module attached to the carrier substrate proximate the controller, the first memory module including a first module substrate and a first memory device attached to the first module substrate; and a second memory module attached to the carrier substrate proximate the first memory module and opposite from the controller, the second memory module including a second module substrate, a second memory device attached to the second module substrate, and an optical transmitter/receiver unit operatively coupled to the second memory device, the first and second memory modules being staged on the carrier substrate such that the second memory module is offset from the first memory module by an amount sufficient to provide an unobstructed path for optical signals between the controller and the optical transmitter/receiver unit of the second memory module. ### Claim 18 (depends on 17) The computer system of claim 17 wherein the controller includes first and second communication units operable to communicate optical signals to the optical transmitter/receiver units of the first and second memory modules, respectively. ### Claim 19 (depends on 17) The computer system of claim 17 wherein the controller includes a communication unit operable to communicate optical signals to the optical transmitter/receiver units of the first and second memory modules.