CMX As Built High Speed Optical ----------------------------------- Original Rev. 29-Nov-2012 Current Rev. 25-Apr-2014 This intent of this note is to record the engineering information about the high speed MiniPOD optical components on the CMX card. - A overall drawing of the connections to the MiniPODs on the CMX circuit board is shown in: 14_high_speed_minipod_optical.pdf - MiniPOD Optical Part Numbers: The high speed optical parts that are used on the CMX card are the following: Transmitter is a 12 channel Avago "MiniPOD" type Avago Part No. AFBR-811FN1Z which translates into: 10 Gbps per lane, Flat ribbon jumper cable, without clip-on heat sink, 100m. Receiver is a 12 channel Avago "MiniPOD" type Avago Part No. AFBR-821FN1Z which translates into: 10 Gbps per lane, Flat ribbon jumper cable, without clip-on heat sink, 100m. These are high speed short range parallel devices designed for multimode fiber systems at a nominal 850 nm wavelength. - Module Pinout: The actual module pinout is common to the transmitter and receiver. There is a separate mechanical identification pin hole. There are 2 holes for screws M1.6 to hold the MiniPOD package down again the supporting circuit board. CMX is using M1.6 x 8mm screws. - Power Filters: Power filters are used for both the 2.5V and 3.3V supplies. Avago recommends 100 nFd to Gnd, 4.7 uH series, 100 nFd to Gnd and 22 uFd to Gnd through a 0.5 Ohm resistor. The MiniPOD power filters on CMX use: 100 nFd and 47 nFd 0603 ceramic capacitors 33 uFd 10 Volt Tantalum capacitors B case with a 0.47 Ohm 0603 resistor ERJ-3RQFR47V 4.7 uH 12.4 mOhm, 7.5 Amp 45 Mhz Wurth No. 7443340470 - MEG-Array PCB Mount Socket: The CMX needs to have a connector from the FCI series 55714 for the MiniPOD optical components to plug into. The CMX is built with a lead free process. The FCI series 55714 socket specification clearly calls out that they do not want you to use their lead free solder ball parts on a leaded assembly process. This is Note #4. See also FCI Specification: GS-20-033. On CMX we use the FCI Part Number: 55714-002LF connector. Note that FCI calls for a 0.58 to 0.64mm pad diameter. Copper defined pads with a solder mask that gives 0.15mm minimum clearance all around the pad. Via not in pad. Tented via. Keep out area of 5.1mm from the perimeter of the part. 0.25mm trace from pad to via. 0.64mm via land. 0.30mm via drill plated. FCI does mark pin A1 on their connectors and on the second page of drawings in the drawing file for the 55714 series of connectors. - High-Speed Differential Signal Routing on the PCB: Between the output of the receivers and the Xilinx GTX serial inputs we need to have DC-Blocking capacitors. They specify 100 nFd capacitors but say that smaller values may work with 8b10b encoding. 100 nFd x 50 Ohms = 5 usec. A bit length is about 0.15 nsec. Why such a big capacitor ? For these Receiver DC Blocking capacitors CMX uses 100 nFd 6.3 Volt X5R Ceramic 0201 Size Kemet Part No. C0201C104K9PACTU. All of the GTX to/from MiniPOD differential traces are routed without any cross overs. Where this non cross over trace routing flips the sign then it can be flipped back on the MiniPOD devices by: Receiver "polarity flip" is controlled from the Receiver Memory Map 01h Upper Page Addresses 226 and 227 Transmitter "polarity flip" is controlled from the Transmitter Memory Map 01h Upper Page Addresses 226 and 227 The GTX transceivers can also flip the sign of their differential signals. In the GTX user manual see page 167 for the transmitter flip and page 216 for the receiver sign flip. Trace length matching: Have 6.4 Gb/s data rate but also need corners so we need the 3rd and hopefully the 5th harmonics, i.e. 19.2 or 32.0 GHz. This is a free space wavelength of 15.6mm or 9.4mm. But for a good transmission line we care about stuff at the scale of one tenth wave length (or smaller). One tenth wavelength is 1.56mm or 0.94mm. But the transmission velocity is only about 50% the speed of light so we care about the physical layout of the traces at the scale of 0.78mm or 0.47mm or smaller. The GTX to/from MiniPOD differential traces were length matched to 0.39mm worst case 0.25mm or better typical. - Physical Mounting: The Flat Ribbon optical cables version of the MiniPOD module has a height of at least 14.50mm above the supporting pcb. With a 14.50mm height it means that there will only be 1.75mm clearance between the top of the MiniPOD module and the inter-board separation plane. Clearance from the MiniPODs to the adjacent L1Calo cards was checked in the "mechanical only" CMX card. As Avago suggests, the MiniPOD external case is connected to the CMX ground via the pcb pads for the M1.6 screws that run into the threaded bosses on the MiniPOD case . - Optical Connection to the MiniPOD: For the optical run from the MiniPOD PRIZM connector to the front panel MTP feedthrough connector the CMX card uses Molex Part No. 106267-2011 cables. The MTP connector on these stub cables has male pins. - MiniPOD TWS Interface with the CMX BSPT FPGA: This is based on Atmel Two Wire Serial EEPROM e.g. AT24C01A but note the difference in the write timing. The MiniPOD module is a "slave" on this bus. There serial bus between the BSPT FPGA an the two transmitter MiniPODs MP1, MP2. There is a separate serial bus between the BSPT FPGA and the three receiver MiniPODs MP3, MP4, MP5. - TWS Management and Monitoring: All Management and Monitoring of the MiniPOD High Speed optical components is handled through the BSPT FPGA. There are separate TWS serial string for the Base Function FPGA transmitters and for the Topological FPGA receivers. There are separate Reset_B signals from the BSPT FPGA to the Base Function transmitter MiniPODs and to the Topological receiver MiniPODs. There is a separate Interrupt_B line from each of the 5 MiniPOD optical components to the Board Support FPGA. The 3 address lines to each of the 5 MiniPOD optical components are brought out to jumpers so that in an emergency the addresses can be changes. There will be only one jumper per address bit, i.e. there is an expected default configuration that will be used - but this allows any address setup in an emergency. The default address configuration is: MiniPOD Device ADR_2 ADR_1 ADR_0 Function ------- ----- ----- ----- ------------------------- MP1 low low low Base Function Transmitter MP2 low low hi Base Function Transmitter MP3 low low low Topological Receiver MP4 low low hi Topological Receiver MP5 low hi low Topological Receiver - Transmitter: The Transmitter has 100 Ohm differential inputs, CML signal level, and does not require DC blocking capacitors. VCSEL, Vertical Cavity Surface Emitting Laser. Management and monitoring are through a Two Wire Serial interface TWS. Can measure light output power LOP and elapsed operating time. The signals or pins involved with the transmitter: 12x high speed differential CML transmit data SCL and SDA for the Two Wire Serial interface 1x Interrupt 3x Address allow you to set the TWS address 1x Reset_B 7x DNC Reserved Do Not Connect 33x Ground 3x 3.3V power 4x 2.5V power The transmitter's maximum current draws are 400 mA from 2.5V and 160 mA from 3.3V. Loss of input signal is typically detected at 120 mVpp differential input. TWS clock rate is 400 kHz maximum. - Receiver: The Receiver has 100 Ohm differential CML level outputs that may require AC coupling capacitors. The receivers use PIN diodes. Management and monitoring are through a Two Wire Serial interface TWS. It can measure: optical input power, temperature, both supply voltages, elapsed operating time. 12x high speed differential CML received data SCL and SDA for the Two Wire Serial interface 1x Interrupt 3x Address allow you to set the TWS address 1x Reset_B 7x DNC Reserved Do Not Connect 33x Ground 3x 3.3V power 4x 2.5V power The receiver's maximum current draws are 525 mA from 2.5V and 90 mA from 3.3V. The differential output voltage from the receiver is controllable over the 100 mVpp to 800 mV range. Common Mode output voltage 2.00 V min 2.54 V max. Note that the differential input to the GTX receiver has a common mode of 2/3 GTX AVTT where AVTT is typically 1.2 Volts --> We must use the AC coupling. Note that the receiver's data outputs can appear as 2.5V through 50 Ohms anytime that the receiver is powered. - Power: No power up sequencing is required. Note that the Power Down must be to <50mV for both 2.5V and 3.3V supplies or the module may not start up correctly next time. - Front-Panel MTP Connectors: Short 12-fiber optical ribbon cables are used to make the MiniPOD inputs and outputs accessible from the CMX card front panel. Two MTP feedthrough connectors are mounted on the card's front panel. In its standard configuration both of the CMX front panel MTP feedthrough connectors will be used for a 12 fiber ribbon cable that runs to a MiniPOD transmitter. This applies to Crate CMX and to System CMX cards processing any data type (EM, jets, etc). The MTP connectors on the CMX stub cables have male pins. If the MiniPOD receivers are required for some application of the CMX card then a specialized optical cables setup will be required. If the MiniPOD receivers are used then it is assumed that one MTP feedthrough will have two 12 fiber ribbons running to the two MiniPOD transmitters and that the other MTP feedthrough will have three 12 fiber ribbons running to the three MiniPOD receivers. These two use cases are illustrated in block diagrams found in: http://www.pa.msu.edu/hep/atlas/l1calo/cmx/hardware/drawings/block_diagrams/ _CMX_Layout_DataPath_Base_Only_Crate.png _CMX_Layout_DataPath_Base_Only_System.png _CMX_Layout_DataPath_with_Topo.png