Liverpool Activities

Tandem Converters for ABCN-25

ABC130 Thermo-mechanicals (first look)

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Tandem Converters for ABCN-25•Initial testing of converter showed Input noise to be higher than expected

•Noise coming in at ~650e to 750e (see below)

Original Converter ‘best’ Input noise

•Found circuit layout had not implemented the ‘Star’ power input as requested

•Single power feed for both converters•Solid ground plane for both converters – not segregated

•Added cut to ground plane to implement thisCut in ground plane

Noise performance is virtually no different between the 2 converters – suggests problem

lies elsewhere

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Tandem Converters for ABCN-252 changes made to module

1.Suggestion from designers at CERN to power the converter from the bond pads (as intended)

•Presently using test pads to bring in power – this is how converters are evaluated at CERN•Circuit layout is symmetrical around this point•Using the test pads introduces an asymmetry (risk of converter currents mixing and thus introducing noise)

•Asymmetry clearly seen in noise plots so far generated – one hybrid always has higher noise

2.Hybrid referencing to Al block modified to be more representative as that on a Stavelet•Reference connections taken from inner edges of hybrids and not outer edges as originally done•Outer edges originally used as it was easier to implement

(617e)

(597e)

(608e)

(639e)

•Numbers in brackets are reference measurement – made using plug-in DCDC•Noise still (slightly) higher but big improvement over previous measurements

•Change in referencing made all the difference•Referencing on stavelet is better implemented – shorter connection paths•Expect stavelet to work as good as shown (if not better)

•For completeness, DTN is clean down to 0.5fC threshold (shown red):

Hybrid 0 0 0 6Hybrid 1 0 0 5Hybrid 2 0 0 36 (known bad chip on this link)Hybrid 3 0 0 1

Tandem converter now shown to work successfully on a single module

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Tandem Converter Module to Al block Referencing

Hybrid Outer Edge References (2 off)

Hybrid Inner Edge References (2 off)

Power Feed to Converter

2nd Sensor HV Contact (buried

under new reference tab)

Tandem Converters for ABCN-25

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•Plan to keep build as close to electrical hybrid (as possible)•Component layer stays as is

•Retain bond pad detail and tracking for wire-bond evaluation•SMD retained – allows tooling and wire-bond evaluation (component clashes etc.)

•Resistive elements to be used to emulate asic heat load•0805 resistors for HCC•Embedded trace for ABC130

2 x 0.5Ω 1/4W for HCC heat load (0.25Ω total)

ABC130 Thermo-mechanicals (first look)

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For ABC130 make use of a resistive serpentine trace embedded on inner layer•Trace geometry is 300µm x 18µm x 75mm per asic location•For 300µm trace width (18µm Cu thickness) resistivity is ~3mΩ/mm•Trace resistance per asic is ~225mΩ

•Circuits are linked up serially •Total resistance ~2.5Ω/hybrid (10 x ABC130 + 1 x HCC)•Hybrids are predicted to consume ~2W (excluding sensor contribution, assume 1W)•2.5V across hybrid gives 2.5W/hybrid (5W/module)•Thus 65W/Stave side (65V/1A per Stave side)

Resistive trace on inner layer for a single asic

•Values are approximate and are susceptible to processing variability.•At 2.5V traces will carry 1A, IPC-2221 suggests ~310µm (external) conductor width for 18µm Cu thickness for 30°C temperature

rise.

ABC130 Thermo-mechanicals (first look)