APD and Electronics Testing
Leon Mualem
Univ. of Minnesota
October 2, 2003
From Concept…
To Reality
Test Cooling Circuitry, Components, and Capacity
Actual board, powered and
cooled to –25C
Higher Value Resistors
Filter on voltage Regulator
Bypassing on Vref and Vcc
Fix Some Issues on Rev. A
Initial Noise msmt at FNAL with new board•MASDA noise best case expected 330 e-
•15 Channels with reduced noise after fixes.•4 @ 390e-
•6 @ 420e-
•3 @ 450e-
•2 @ 480e-
•Reminder: This is an interim solution, a properly matched front end should get ~250e- according to Tom Zimmerman
Channel Noise (RMS e-)
1 390
2 390
3 390
4 420
5 390
6 420
7 420
8 420
9 420
10 450
11 420
12 450
13 480
14 450
15 480
18 M
eg O
hms
9 M
eg O
hms
Noise testing parameters
• Maximum bandwidth setting
• 21mV/fC gain 300e-/mV
• 1mV=1ADC count
• Integration Time (SAFT-SBEF) = 2s
Noise Levels on Bare Board
W/10pF
W/18M W/9M
Fit to noise showing Tails…there aren’t any
Breakdown Voltage vs. TempVbr I=15uA
375
380
385
390
395
400
405
410
415
-25 -15 -5 5 15 25 35
Temperature (C)
Bre
ak
do
wn
vo
lta
ge
Current vs. Voltage by temp.
0.1
1
10
100
1000
10000
300 320 340 360 380 400
Voltage
Cu
rren
t (n
A)
25
20
15
10
5
0
-5
-10
-15
-19
Noise vs. Voltage by temp.
100
1000
10000
100000
300 320 340 360 380 400
Voltage
RM
S n
ois
e (
ele
ctr
on
s) 25
20151050-5-10-15-19
Issues …
• Cooler plate must not be left floating – Electrically connect to
board
Future Plans
• Measure noise with powered APD
• Measure noise with APD vs. Temperature • Gain measurement with Temperature
• Measure noise as a function of Tint
• Measure LED generated signal
• Measure signal from scintillator with trigger
• …
