---+ MGNGSQ4 - McGill Next Gen SQUID controller info page

Background

This SQUID controller was designed in the context of the Canadian Space Agency contract to demonstrate a flight version of the SQUID controller that could also accomodate the new requirments for DAN. The components were selected so there would be a direct Space-Qualified equivalent, so there has been some engineering compromises.

The features of this SQUID controller are:

• Supports 4 SQUID channels
• Is compatible with previous cryostat DB37 connector
• Its height is half that of the previous board. Two boards can be stacked vertically to process 8 channels.
• Has no analog flux lock loops - The SQUID output is simply amplified and sent to the Mezz board
• Operates on a single +5.5V supply
• The Mezz connector is a DB37 male with different pinout. The connector include analog signals, digital SPI/LVDS interface and power.

The first MGNGSQ4 Rev0 is the COTS (Commercial Off-The-Shelf) version using standard commercial components that have Space Qualified equivalents.

As part of the CSA project, our partner Com Dev will redesign the board as needed to build a FLight representative version that will undergo thermal tests.

Major Rev 0 Board changes

• Replace C9 for each Squid Channel with 10uF capacitor (can just solder capacitor ontop if easier) - Squid_Channel page of schematic
• Replace L9 for each Squid Channel with 50 Ohm resistor - Squid_Chanel_DACs page of schematic

R26 may want to be increased from 500 Ohms to 2k to improve resolution. Is this neccessary Tijmen?

REV2 SQCB Schematics

Schematics (as of August 19th), which includes the change to R8:

* SQUIDCtr_Rev2_19thAug2013.pdf: REV2 SQCB Schematics August 19th, 2013

Major Rev 2 Board changes

• SDA needs pull-up
• R8 Changed from 11K to 9.76K to lower the DAC_VREF

Serials 12-01 & 05-01 (Both REV 2)

R8 changed from 11k to 9.76k, to lower the gain of the Op-Amp supplying the DAC_REF_VOLTAGE. This brings the buffer that provides the dac reference voltage off its rail, keeping the voltages from bouncing when the DACs pull maximal current.

ALSO: In the REV0 boards the L9 Inductor was replaced with a 50 Ohm Resistor to prevent the Op-Amp supplying the Analogue Reference Voltage from ringing. This problem is NOT observed in the REV2 boards. Since the addition of the resistor actually makes the current through the squid dependent on the Stage 1 Offset voltage (albeit slightly), this change is not recommended for the REV 2 boards. Current schematics have the L9 position populated with a 1uH inductor, and this should remain true.

MGNGSQ4 Rev 0

• Design
  • Pre-fabrication Schematic and PCB Verification, MGNGSQ4 Rev0
• Schematics
• PCB
• Testing
  • Preliminary Board testing
• Tracking

-- JeanFrancoisCliche - 2012-06-14

MGNGSQ4 Rev 0 - Board changes

Serial 05-01

Changing R26to 2k Ohms, this improves resolution on voltage offset. Tijmen test uses 2.5V to 2.8V with R26 500Ohms (Channel 2-4, Channel 1 is 1kOhm).

On all four channels (2013-04-04):

1. Changed R26 to 2k Ohms.

2. Changed C9 to 10 microF.

3. Changed L9 to 50 Ohms.

Modules 1-4:

R11 & R39 have been removed, and The transformer is populated.

Module 4 has an integrator circuit added for the analog flux lock loop. The integrator op amp is powered on using the flux bias dac of module three.

R59_1 was changed from 100 Ohms to 1KOhm.

Serial 04-01

On all four channels:

1. Changed R26 to 2k Ohms.

2. Changed C9 to 10 microF.

3. Changed L9 to 50 Ohms.

Modules 1-4:

For testing old vs new nuller circuit, R11 & R39 have been removed, and The transformer is populated.

Serial 03-01

Pin is stuck in cryostat side connector, will eventually have to be replaced. Seems fine for desktop testing though. Added 10uF across C8 to channel 1. This was done because at low frequency levels I could see the refererance voltage voltage across C8 bouncing. This greatly effected the frequency response.

See plot below:

* Comparing DanSquidController U2 frequency response with and without 10uF across C8:

Serial 06-01 (REV 0)

Posted to: Nicholas Harrington Berkeley

Board had had 10uF capacitors added and the inductors replaced with 50Ohms as discussed in the major board changes section.

Serial 06-01 (REV 2)

Posted to Graeme

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This topic: AnalogFMux > WebHome > MGDSQ4 Topic revision: r21 - 2013-08-19 - JoshuaMontgomery

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