UCSB CMS Weekly Status Meeting CMS Tracker Rod Filters Sam Burke EE Slide 1

Rod Power Line Low-Pass Filter Study

3 August 2004

Sam Burke

UCSB HEP Group

UCSB CMS Weekly Status Meeting CMS Tracker Rod Filters Sam Burke EE Slide 2

Progress

• Noise on CERN Rod Test System Power line is source per battery tests 2.5 mV @ 1Mhz measured on Rod PS @UCSB

• Low Noise on UCSB Rod System 1 - 2 A/D Counts

UCSB CMS Weekly Status Meeting CMS Tracker Rod Filters Sam Burke EE Slide 3

Progress• Inject Noise into UCSB system

introduce noise pulse train into 0.1 ohm resistor placed at common power supply point and observe system response. Frequency near Tracker Shaper Band.

• Reduce self-induced noise with filtering Place Low Pass Filter on power line Shaper Noise Band Defined

– 1/260ns =4Mhz to 1/40ns =25Mhz

– >60dB attenuation in shaper band

UCSB CMS Weekly Status Meeting CMS Tracker Rod Filters Sam Burke EE Slide 4

Low Pass Filter Schematic

UCSB CMS Weekly Status Meeting CMS Tracker Rod Filters Sam Burke EE Slide 5

LP Filter Response

UCSB CMS Weekly Status Meeting CMS Tracker Rod Filters Sam Burke EE Slide 6

LP Filter Test Results

UCSB CMS Weekly Status Meeting CMS Tracker Rod Filters Sam Burke EE Slide 7

LP Filter

• Break 2 power lines and common line and insert filter.

UCSB CMS Weekly Status Meeting CMS Tracker Rod Filters Sam Burke EE Slide 8

Open Filter Issues• Voltage drop

Vgnd=IR=19A*4.9mohms=93mV on Gnd V+2.5=IR=12A*4.9mohms=60mV on 2.5V line

• Heat Generation I^2R=19^2*.0049ohms=1.7 watts on Gnd coil I^2R=12^2*.0049=0.7 watts on 2.5V line coil I^2R=7^2*.0049=0.24 watts on 1.25V line coil

• Core Saturation in Machines Magnetic Field Open core may saturate in field Investigate toriod candidate

UCSB CMS Weekly Status Meeting CMS Tracker Rod Filters Sam Burke EE Slide 9

Alternate Filter Approach

• Move filter outside of CMS magnetic enviornment No saturation of filter inductors Need to insert (splice) filter into Rod Power Cables

• Reduce heat generation by filter I^2 heating Use lower winding resistance with a reduced noise

attenuation if acceptable

UCSB CMS Weekly Status Meeting CMS Tracker Rod Filters Sam Burke EE Slide 10

Alternate Inductor Impact

UCSB CMS Weekly Status Meeting CMS Tracker Rod Filters Sam Burke EE Slide 11

Rod LP Filter Prototype

• High Current Inductors are on the two DC Power lines.

• Twisted pairs are power sense lines and analog sensor lines

UCSB CMS Weekly Status Meeting CMS Tracker Rod Filters Sam Burke EE Slide 12

LP Filter At Rod Pwr. Line

UCSB CMS Weekly Status Meeting CMS Tracker Rod Filters Sam Burke EE Slide 13

Pulse Transformer

UCSB CMS Weekly Status Meeting CMS Tracker Rod Filters Sam Burke EE Slide 14

Rod Module 1

• Top: Noise injection of 10 ns pulse, 30 mhz, 10vpk into power supply common.

• Bottom: Low Pass Filter in Power Circuit

UCSB CMS Weekly Status Meeting CMS Tracker Rod Filters Sam Burke EE Slide 15

Rod Module 3 (under CCU)

• Top: Noise injection of 10 ns pulse, 30 mhz, 10vpk into power supply common.

• Bottom: Low Pass Filter in Power Circuit

UCSB CMS Weekly Status Meeting CMS Tracker Rod Filters Sam Burke EE Slide 16

Rod Module 6

• Top: Noise injection of 10 ns pulse, 30 mhz, 10vpk into power supply common.

• Bottom: Low Pass Filter in Power Circuit >40% reduction in noise Normal UCSB background

level is ~2.5 a/d counts

UCSB CMS Weekly Status Meeting CMS Tracker Rod Filters Sam Burke EE Slide 17

Future Plans

• Create CERN like noise pattern adjust frequency of pulser can we filter this out?

• Study power supply sense-line filtering

• Test filter on CERN Rods that are experiencing high noise.