Stave module with External Shunt Regulation

BNL shunts (Dave Lynn/Phil Kuczewsk)

•External shunts provide an alternative source of voltage regulation for a hybrid•Hybrids currently come with a distributed shunt scheme (Mshunt)

•Regulator circuit on board hybrid with 2 off bypass transistors per ABCN-25•External shunt uses an external regulator circuit with a single bypass transistor (mounted on a plug-in)

•Mshunt disabled by connecting control lines to hybrid (local) ground on plug-in

•2 flavours of shunt plug-ins available:

1.BNL shunt, fixed output voltage (preset to 2.6V)•2 off provided, used as a first proof of principle on a module

2.Liverpool shunt, output voltage trimmable over the range 2.6V to 3.0V (set to 2.6V)•8 off available to complement a stavelet

Liverpool Shunts

Stave module with BNL Shunt Regulator - results

3PT Gain Input Noise @1fC

601e

590e 600e

591e

Dtnoise @1fC Dtnoise @0.75fC

0

0

1259

1262

0

1

24510

23929

0

1

1243

1249

662

26

6822

7559DC

AC

DC

AC

Dtnoise scans

•Numbers in black are the sum(hits) for BNL Plug-in•Red is the sum(hits) for the on-board shunt regulator

•Noise bands present irrespective of the shunt regulation scheme with no additional decoupling capacitors

586e

611e

609e

588e

•Dtnoise is clean down to 0.75fC for both BNL and Liverpool shunts

•Once decoupling is added

•Dtnoise plot at 0.5fC is shown for Liverpool plug-in•Numbers in black are the sum(hits) for Liverpool shunt•Red is the sum(hits) for the BNL shunt

204

93

122

85

Stave module with Liverpool Shunt Regulator - results

3PT Gain Input Noise @1fC

Dtnoise scans with decoupling capacitors added (as prescribed by Peter Phillips)

131

53

1641

1444

Dtnoise @0.5fC

Summary

•External shunt regulation for the powering of module has been shown to work

•Input noise is as expected at ~600e ENC

•The Dtnoise scans show noise bands at 1fC – this is true for both the BNL and Liverpool shunts•As is the case for the onboard Mshunt

•Additional capacitive decoupling is required to recover Dtnoise performance•Both external shunts provide clean occupancies down to 0.75fC•Only at low threshold of 0.5fC do we see evidence of the noise bands

•Currently have 8 Liverpool shunts tested and have now been shipped to RAL for stavelet testing