... | ... | @@ -12,3 +12,76 @@ click on the component and then on the "Documentation" tab). |
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WholeBoard.jpg
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On this card will be connected all the future time measurement elements
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will be connected. So, the goal of this board is only to convert the
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analog data in numerical ones. As we want the best possible resolution
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for the ADC, we pay extremely attention to the noise generated by the
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other components. This board is a carrier card for the
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[MicroZed](http://zedboard.org/product/microzed) board which will be
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used to process incoming data.
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The design schematics are divided into 5 different parts :
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\> \# the first ADC,
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\> \# the second one,
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\> \# the clock splitter circuitry,
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\> \# the MicroZed Board connections,
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\> \# the power supply
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This schematic is only to show the different connections between these
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different parts. In addition to the power lines and data lines, we can
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see the SPI bus between the MicroZed and both the ADC.
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## The two ADC
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As the schematics for the two ADC are the same, we only put one of them
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here.
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ADC1.jpg
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We have two inputs for each ADC. On each input are one SMA connector for
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ground referenced signals and two others for differential ones. All
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inputs have an impedance around 50 ohm on a two decades bandwidth
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(200kHz to 20MHz).
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A particular attention is given to the power supply decoupling. Multiple
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capacitors with multiple values are placed to reduce the impedance on a
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large bandwidth and then avoid the noise to disturb the measurements.
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This has been done as well for the analog power lines as for the digital
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ones.
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The clock signal arrives from the splitter on a differential line.
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## The clock splitter
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clockSplitter.jpg
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This part is used to synchronise both the ADC by giving them the same
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clock signal. This clock splitter allows us to use different clock
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frequencies in a range from 5 MHz to 125 MHz. This component can also
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filter the input clock signal. The parameters of that filter can be set
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using the `FILTA` and `FILTB` inputs. To be able to change the filter
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and to adjust it to our needs, we put these inputs on jumpers.
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## The power Supply
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We need enough power to supply all the components on the board but also
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the MicroZed board. Furthermore, these components needs different
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voltage levels.
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The first stage is a buck converter. It is use to convert the voltage
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from 12 V to 5V DC. These 5 V are needed by the MicroZed board. We then
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converter these 5 V in a 3.3 V one. This last is used to supply the
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clock splitter. Finally, two LDO are used to regulate the digital and
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analog power supplies of the ADC.
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## External connections
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FCI.jpg
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The connections to the MicroZed board are done via its FCI connectors.
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All these inputs can be configured to work in LVDS. As the output of our
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ADC are already in LVDS, it fits ideally with our project.
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In addition to these connections to the ADC, we also provide the board
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other connections to be able to use the other MicroZed GPIO.
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