The SQUID Control board is basically the same as was used for SPT and APEX. It sits after the dfMUX motherboard (which is our main focus of design) and provides and processes the analog signals needed for the bolometers.
The board contains an FPGA, which is controlled by the main dfMUX motherboard through a large connection to the side of the board. The motherboard is responsible for determining what the various inputs should be, and the on-board FPGA sets them through a DAC.
Here is one of the eight channels present on the board with a little description following
The inputs on the right hand side are as follows:
squid_out+- - These are connections directly out to allow for a four point connection to the SQUID. The idea is that if you provided a voltage along the same set of wires as you read the current some would drop in the wires, leaving you with a different amount running through the SQUID itself.
flux_bias - For a detailed explanation please see the page on SQUIDS but basically, the coil that's in front of the SQUID coil has to be biased with the correct flux to give a particularly sensitive.
squid_bias - Much like the flux bias, the purpose this is better explained on the SQUID page but basically the SQUID also has to be biased to the current current for operation.
voffset - The op amp (labelled OPA847ID) causes some current to be drawn through the system, to account for this Voffset can be set to get the output to be 0, basically zeroing the whole system.
amp_out+- - Sweet sweet signal. These come in from the SQUIDs themselves, and go through two stages of amplification. The first is the op amp (OPA847ID) which is called stage 1 and amplifies directly the output of the SQUID. The second (THS4131CD) is a differential amplifier that takes the original signal and makes it differential (encoded in the difference between amp_out+ amp_out-), so that it can be passed through a long wire without being degraded.
The top part is various feedback inputs and the nulling wave, which will be discussed soon.
-- KevinMacDermid - 30 May 2007
This topic: Main > WebHome > EBEX > SQUIDControlBoard Topic revision: r1 - 2007-05-30 - KevinMacDermid
The inputs on the right hand side are as follows:
squid_out+- - These are connections directly out to allow for a four point connection to the SQUID. The idea is that if you provided a voltage along the same set of wires as you read the current some would drop in the wires, leaving you with a different amount running through the SQUID itself.
flux_bias - For a detailed explanation please see the page on SQUIDS but basically, the coil that's in front of the SQUID coil has to be biased with the correct flux to give a particularly sensitive.
squid_bias - Much like the flux bias, the purpose this is better explained on the SQUID page but basically the SQUID also has to be biased to the current current for operation.
voffset - The op amp (labelled OPA847ID) causes some current to be drawn through the system, to account for this Voffset can be set to get the output to be 0, basically zeroing the whole system.
amp_out+- - Sweet sweet signal. These come in from the SQUIDs themselves, and go through two stages of amplification. The first is the op amp (OPA847ID) which is called stage 1 and amplifies directly the output of the SQUID. The second (THS4131CD) is a differential amplifier that takes the original signal and makes it differential (encoded in the difference between amp_out+ amp_out-), so that it can be passed through a long wire without being degraded.
The top part is various feedback inputs and the nulling wave, which will be discussed soon.
-- KevinMacDermid - 30 May 2007
| I | Attachment | Action | Size | Date | Who | Comment |
|---|---|---|---|---|---|---|
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CosMeeting-May30th.png | manage | 70.8 K | 2007-05-30 - 15:21 | KevinMacDermid |
This topic: Main > WebHome > EBEX > SQUIDControlBoard Topic revision: r1 - 2007-05-30 - KevinMacDermid
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