Effect of flat cable to MPPC signal

1
Effect of flat cableto MPPC signal

• S. Uozumi (Kobe)
• Jun-6 2008 ScECAL meeting

2
Readout cable
Idea 1
Idea 2
Just adopt long flat cable with MPPC (as done in
DESY BT).
Idea 3
3
Objective

• How the MPPC signal skewed by passing through
  industrial-standard FPC cables and connectors?
• Any reflection clearly seen?
• This will determine (or give a feeling) specs of
  our readout flat cable (inpedance, length).
• Electrocal cross-talk between adjacent lines on
  the flat cables?

4
Setup

• 20-lines FPC cables with 15cm length 1.25mm pitch
  and FPC connectors are used.

FPC cable
FPC connector
Readout circuit
MPPC
Relay board
MPPC
Signal connected to Oscilloscope Through x63 amp
5
Dark noise signal with different cable length
With one cable (15 cm)
With two cables And relay board (30 cm)
6
Electrical cross-talk
Adjacent channel
Signal channel
Amount of electrocal cross-talk on the flat cable
is at least below noise level.
7
Conclusion

• Of course those checks are not perfect, but
• we can somehow learn
• Better to set the cable inpedance to 50ohm,
• even if it makes production cost 20 higher.
• (it was NOT considered at the DESY BT.)
• Electrical cross-talk on flat cable is not
  significant level.
• I suppose to go ahead with idea-I, but with 50ohm
  flat cable, not industrial standard FPC cable.
• But, if the cable length can be short enough,
• taking idea-3 is also possible(but with
  50ohm cable).