Vertilon SIB164B, Руководство пользователя

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SIB164B PMT Sensor Interface Board for Hamamatsu H7546B / H12428 Series
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Vertilon Corporation, 66 Tadmuck Road, Westford, MA 01886
/
Tel: (978) 692-7070
/
Fax: (978) 692-7010
/
www.vertilon.com
Leading Edge Discriminator
The leading edge discriminator is a simple timing circuit that generates a trigger signal when a charge pulse on the last
dynode output from the H7546B / H12428 PMT exceeds a user-defined threshold. It is implemented using a high speed
comparator connected to the output of the last dynode preamplifier. Referring to Figure 6, negative going pulses from the
preamplifier are compared to the discriminator threshold that is set through the SIB164B dialog box in the PhotoniQ GUI.
A logic high (for
positive polarity control) is generated on the trigger output (SMB connector J5) after a small delay (t
d1
)
from when the pulse first crosses the threshold, V
th
. The trigger LED flashes indicating that a current pulse crossed the
threshold. The discriminator switches back to a logic low when the pulse crosses the threshold from the opposite direction
as it returns back to the baseline level. Because the trigger point is sensitive to the pulse height, this discriminator is
typically used in applications that do not require precision timing.
Figure 6: Leading Edge Discriminator Timing
PREAMP
OUTPUT
V
th
t
d1
TRIGGER
POINT
THRESHOLD
POINT
TRIG OUT
LAST
DYNODE