power supply cable charge injection 3 channels readout (external cables to the scope) 3 channels...
Post on 19-Dec-2015
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Power supply cable
Charge injection3 channels readout
(external cables to the scope)
3 channels readout
(internal cables)
Set up for reading two cards
3 channels readout Charge Injection
Testing one card at a time
Reading one card
3 channels connected
Output signals are reasonable
The quality of the output signal improves when the grounds of the input and output cables were connected inside the box
Same for both cards
Grounds of input and output cables are connected
Single channel - Single card (2)
-30
-25
-20
-15
-10
-5
0
-10 -8 -6 -4 -2 0 2 4 6 8 10
Time (ns)
mV
Single channel Single Card (1)
-30
-25
-20
-15
-10
-5
0
5
10
-10 -8 -6 -4 -2 0 2 4 6 8 10
Time (ns)
mV
Testing one card at a time with one channel connected – signal recorded from main channel
Long tail
Ringing/oscillations in the tail
Single channel Single card (1) ground
-120
-100
-80
-60
-40
-20
0
20
-10 -8 -6 -4 -2 0 2 4 6 8 10
Time (ns)
mV
Single channel single card (2)
-120
-100
-80
-60
-40
-20
0
20
-10 -8 -6 -4 -2 0 2 4 6 8 10
Time (ns)
mV
Long tail, oscillations reduced when the grounds of the input and output inside the box are connected
Gain is also increased
Testing one card at a time with one channel connected – signal recorded main channel
Two channels Single Card (1)
-120
-100
-80
-60
-40
-20
0
20
-10 -8 -6 -4 -2 0 2 4 6 8 10
Time (ns)
mV
Two channels single card (2)
-100
-80
-60
-40
-20
0
20
-10 -8 -6 -4 -2 0 2 4 6 8 10
Time (ns)
mV
Testing one card at a time with two channels connected – signals recorded from main channel
3 channels single card (1)
-100
-80
-60
-40
-20
0
20
-10 -8 -6 -4 -2 0 2 4 6 8 10
Time (ns)
mV
3 channels single card (2)
-100
-80
-60
-40
-20
0
20
-10 -8 -6 -4 -2 0 2 4 6 8 10
Time (ns)
mV
Testing one card at a time with three channels connected – signal recorded from main channel
3 channels 2 cards (1)
-140
-120
-100
-80
-60
-40
-20
0
20
40
-10 -8 -6 -4 -2 0 2 4 6 8 10
Time (ns)
mV
3 channels 2 cards (2)
-50
-40
-30
-20
-10
0
10
20
-60 -40 -20 0 20 40 60
Time (ns)
mV
Testing one card at a time with three channels connected – signal recorded from main channel
Reasonable signal recorded from bottom card (card 1), but with bad oscillations
Very bad oscillations on top card (card 2)
Signals in the two cards do not behave in the same manner
Summary of current status
Can read one channel from one card
Signal quality improves when the grounds of cables for the input and output inside the shielding box were connected
With this configuration, signals in the main channel are reasonable in terms of time response and gain, even when the neighbour channels are connected
When both cards are connected, signals from one card has a long tail and the other with significant oscillations.
Work to do:
To investigate the problem when two cards are connectedTo investigate possible injection from pulse generator into the ground
Other observations:
As soon as pulse generator is connected to the shielding box, there is a potential difference around the box (ie. the potential is not homogeneous across the box).
The pulse generator seems to disturb the ground potential.
The pulse generator was set to have a 50ohm impedance.
A signal is observed at the ground pin once the pulse generator is connected.