This invention relates to a programmable integrated circuit device, and particularly to a programmable integrated circuit device having an integrated optical-electronic interface for high-speed off-device communications.
As data-intensive electronic devices and applications proliferate, data rates continue to increase. In many applications, integrated circuit devices are able to function at sufficiently high data rates, but copper wire used to connect such devices to each other or to system backplanes has become a bottleneck to those data rates. For example, devices may be capable of operating internally at rates at or exceeding 10 Gbps, but external bottlenecks are caused by signal frequency-dependent loss and reflections at the backplane level, which may cause severe inter-symbol interference (ISI).
Optical signaling is one alternative that supports higher data rates because the loss of optical fiber may be “virtually” zero compared with copper. However, conversion from on-device electrical or electronic signaling to off-device optical signaling presents its own challenges. This is particularly the case where the integrated circuit device is programmable, such as, e.g., a field-programmable gate array (FPGA) or other programmable logic device (PLD). This is because the very nature of a PLD is to provide flexibility to the user (i.e., to the manufacturer of a product who incorporates PLDs into the product). Therefore, the particular type of optical-electronic interface needed will not be known by the PLD manufacturer, nor will the location on the PLD of the particular input/output (I/O) circuits to which an optical-electronic interface will need to be connected be known to the PLD manufacturer.
One solution is to provide a plurality of different optical-electronic interfaces on a printed circuit board (PCB) on which the PLD also is mounted, along with an assortment of optical-electronic connectors. Thus, a single such PCB may include one or more of each of the following types of optical-electronic interfaces and connectors:
1. XFP (10 Gigabit Small Form Factor Pluggable Module), which is a hot-swappable, protocol-independent optical transceiver for 10 Gbps applications.
2. CFP (C (100 in Latin) Form-Factor Pluggable Module) for 100 Gbps applications.
3. SFP (Small Form-Factor Pluggable Module), also known as Mini-GBIC, which is a compact, hot-swappable transceiver for 4.25 Gbps applications. SFP+ may operate up to 10 Gbps.
4. QSFP (Quad SFP), which replaces four single-channel SFPs in a package about 30% larger than a single-channel SFP, for 10 Gbps applications, with an effective throughput of 40 Gbps.
This makes for a bulky PCB, and also introduces additional wire paths from the PLD I/O ports to all of the various interface modules on the PCB.
According to another solution, one or more discrete optical-electronic interface components may be incorporated into the same package as the PLD die for use with one or more of the high-speed serial interfaces of the PLD. However, one disadvantage of such a solution is that while optical transceiver I/O channels are provided at the package level, electrical I/O pins are consumed at the die level to provide control signals to the optical-electronic interface components, reducing the number of I/O pins that can be provided for users at the package level—e.g., for clocks and controls.
Various embodiments of the present invention incorporate an optical-electronic interface into a PLD, freeing up all of the electrical I/O pins. In further embodiments, rather than having to commit a particular transceiver I/O to being either optical or electrical, switchable electrical/optical transceiver I/O channels can be provided.
According to an embodiment, electronic portions of each optical-electronic interface—i.e., portions of one optical-electronic receiver interface and of one optical-electronic transmitter interface—may be incorporated into the PLD die, leaving only the optical portions as discrete components. The optical portions may be surface-mounted on the die, or connected by wires to the die and packaged in the same package as the die.
According to an embodiment, some of the optical portion of the transmitter and receiver interface—specifically, the laser driver (LD) on the transmitting side, and the transimpedance amplifier/limiting amplifier/automatic gain control (TIA/LA/AGC) on receiving side, which actually are electronic—may be incorporated into the PLD die along with the other electronic portions, leaving only the photodiode of the optical-electronic receiver interface and the laser and optical portion of the optical-electronic transmitter interface as discrete components. Once again, the optical portions may be surface-mounted on the die, or connected by wires to the die and packaged in the same package as the die.
According to an embodiment, all of the optical portions of both the receiver optical-electronic interface and the transmitter optical-electronic interface may be incorporated into the PLD die along with the electronic portions, leaving only the optical fiber connectors external to the die (and the package).
In any of the foregoing embodiments, it may be desirable to provide to the user the option of using one or more high-speed serial interface channels in either optical or electrical or electronic mode. Therefore, each of the foregoing embodiments may have one of the following three variants:
In a variant, optical-electronic interfaces would be provided for all of the high-speed serial interface channels and the user would not be given any option for a high-speed serial electrical or electronic interface. A user who wanted electrical or electronic interface capability would have to choose a different model of PLD.
In a variant, a mix of optical and electrical or electronic high-speed serial interface channels would be provided, by providing optical-electronic interfaces for only some of the high-speed serial interface channels on the PLD. If this variant were adopted, different models of the same PLD might be provided with different proportions of electrical or electronic and optical channels.
In a variant, optical-electronic interfaces would be provided for all of the high-speed serial interface channels, but the user would be able to programmably select between optical and electrical or electronic operation for some or all of the high-speed serial interface channels. For example, a programmable interconnect component, such as a multiplexer, could be provided in some or all of the high-speed serial interface channels to allow the channel to be programmably connected either to a conventional electrical or electronic I/O pin, or to an optical-electronic interface.
Further features of the invention, its nature and various advantages will be apparent upon consideration of the following detailed description, taken in conjunction with the accompanying drawings, in which like reference characters refer to like parts throughout, and in which:
As seen in
In system 200 shown schematically, and not to scale, in
On OSA 300, connections 311 are coupled to a control circuit 321, which is in turn connected to optical portion 323. A connector, such as a standard MT optical fiber connector 302, is attached to optical portion 323. MT connection 302 may terminate up to 72 optical fiber connections, although the aforementioned LightABLE™ optical engine provides only 12 optical channels. In receiver OSA 201, optical portion 323 includes a photodiode detector 241, and a transimpedance amplifier/limiting amplifier/automatic gain control (TIA/LA/AGC) 251. In transmitter OSA 202, optical portion 323 includes an array of vertical-cavity surface-emitting lasers, or VCSELs 242, and suitable laser driver (LD) circuitry 252 for the lasers.
Although shown schematically in
Although system 200 provides a single package, the need to electrically interconnect FPGA 101 and OSAs 201, 202 consumes conventional I/O ports of FPGA 101, reducing the number of conventional I/O ports available for user applications. The present invention eliminates or greatly reduces the need to consume conventional I/O ports of FPGA 101.
In embodiment 400 shown in
In embodiment 500 shown in
In embodiment 600 shown in
Although each of embodiments 400, 500 and 600 is shown with a single pair of receiver OSA 201 and transmitter OSA 202, additional pairs of receiver OSA 201 and transmitter OSA 202 may be provided if the number of optical channels in a particular implementation of the device exceeds the number of channels that can be serviced buy a single pair of receiver OSA 201 and transmitter OSA 202.
As discussed above, while according to a variant of any of embodiments 400, 500, 600, all of the high-speed I/O channels may be optical, meaning that all of the high-speed I/O channels of FPGA core 411 are connected to optical interfaces, it may be desirable to provide a mix of electrical or electronic high-speed channels and optical high-speed channels. According to another variant of any of embodiments 400, 500, 600, only some of the high-speed I/O channels of FPGA core 411 are connected to optical interfaces, while the remaining channels are connected to conventional I/O pins for use as electrical or electronic channels. Different implementations of this variant may have different proportions of optical and electrical or electronic channels.
According to another variant of any of embodiments 400, 500, 600, each high-speed I/O channel, or each member of a subset of the high-speed I/O channels, on FPGA core 411 is switchably connectable to either an optical interfaces or to a conventional I/O pin. As shown in
Although the embodiments described above are based on incorporation of some or all of the components of the aforementioned optical engines into an FPGA (or other PLD) die, other interface technologies, including both electronic and optical components, may be used instead. Thus, a PLD die may incorporate any photodiode or other photodetector, any laser or laser array, any laser driver, any optical modulator/demodulator circuitry, optical wavelength division multiplexing (WDM)/demultiplexing circuitry and/or AGC circuitry. The optical components can be fabricated using hybrid silicon technologies such as silicon photonics, and can be interconnected optically, using, e.g., hybrid CMOS optical waveguide technology. And as already noted, PLDs according to embodiments of the invention may include a mix of standard electrical or electronic I/Os, high-speed electrical or electronic I/Os, and optical high-speed I/Os.
As an example, a high-speed transmitter channel 801 seen in
As another example, a high-speed receiver channel 901, as seen in
It will be appreciated that the recitation of data rates of 10 Gbps in the foregoing examples is merely exemplary. The individual channels could operate at any data rate, e.g. from 10 Gbps to 50 Gbps, or even faster. Moreover, although the embodiments described above, in each of
This claims the benefit of, commonly-assigned U.S. Provisional Patent Application No. 61/468,471, filed Mar. 28, 2011, which is hereby incorporated by reference herein in its entirety.
Number | Name | Date | Kind |
---|---|---|---|
5631988 | Swirhun et al. | May 1997 | A |
6821029 | Grung et al. | Nov 2004 | B1 |
6945712 | Conn | Sep 2005 | B1 |
7215891 | Chiang et al. | May 2007 | B1 |
7729581 | Rolston et al. | Jun 2010 | B2 |
20030010988 | Franson | Jan 2003 | A1 |
20030072537 | Eichenberger et al. | Apr 2003 | A1 |
20030201462 | Pommer et al. | Oct 2003 | A1 |
20050084269 | Dallesasse et al. | Apr 2005 | A1 |
20050232635 | Aronson et al. | Oct 2005 | A1 |
20050286902 | Pierce et al. | Dec 2005 | A1 |
20060088254 | Mohammed | Apr 2006 | A1 |
20060120660 | Rolston et al. | Jun 2006 | A1 |
20070258683 | Rolston et al. | Nov 2007 | A1 |
20080226228 | Tamura et al. | Sep 2008 | A1 |
20100054754 | Miller et al. | Mar 2010 | A1 |
20110216998 | Symington et al. | Sep 2011 | A1 |
20110249936 | Welch et al. | Oct 2011 | A1 |
20140144971 | Conn et al. | May 2014 | A1 |
Number | Date | Country |
---|---|---|
101103560 | Sep 2008 | CN |
2008-523581 | Jul 2008 | JP |
WO03032021 | Apr 2003 | WO |
WO2005093973 | Oct 2005 | WO |
Entry |
---|
“The 50G Silicon Photonics Link,” Intel Labs, White Paper, Jul. 2010, pp. 1-5. |
“Reflex Light on Board®—Xilinx Virtex V Optically Enabled FPGA (OE-FPGA),” presentation given by Reflex Photonics Inc., The Light on Board® Company, Document # LA-970-056-00 Rev. 1, Nov. 2008, 13 slides. |
Number | Date | Country | |
---|---|---|---|
20120251116 A1 | Oct 2012 | US |
Number | Date | Country | |
---|---|---|---|
61468471 | Mar 2011 | US |