1 mgpa linearity mark raymond (dec.2004) non-linearity measurements in the lab hardware description...
Post on 19-Jan-2018
229 Views
Preview:
DESCRIPTION
TRANSCRIPT
1
MGPA Linearity
Mark Raymond (Dec.2004)
Non-linearity measurements in the lab
hardware description method results
2
Linearity test bench
Digital Sequencer
AWG(AG33250)
programmableattenuator
(HP8494+HP8495)1 db steps
MGPA 14-bit ADC(SIS3301)
prog. delay(0 – 250 ns1 ns steps)
trig.
trig.10ns
AWG
prog.attenuator
14-bitVMEADC
MGPAtest
board
prog.delay
levelshift
LabView automated
use prog. attenuator, ratherthan changing amp. of AWG O/Pto avoid contribution from AWGO/P stage linearity
14-bit ADC -> negligible INLand DNL contribution tomeasurement
for MGPA test board use either RAL PCB with socket easy chip exchangeor VFE card verify performance in final configuration
40 MHz clock and ADC trig.
Cinj
3
MGPA test board photosRAL board with socket
modified VFE card (latest version)
APD inlight tightenclosure diff. to s.e.
conversion
differentialMGPA O/Psignals accessedbetween MGPAand ADC
chargeinjection
4
Linearity measurement procedure
Digital Sequencer
AWG(AG33250)
programmableattenuator
(HP8494+HP8495)1 db steps
14-bit ADC(SIS3301)
prog. delay(0 – 250 ns1 ns steps)
trig.
trig.
levelshift
Digital Sequencer
AWG(AG33250)
programmableattenuator
(HP8494+HP8495)1 db steps
MGPA 14-bit ADC(SIS3301)
prog. delay(0 – 250 ns1 ns steps)
trig.
trig.40
MHz10ns
levelshift
1) remove MGPA test board and characterise system => make precision measurement of attenuator steps
50ns CR-RC shape
2) replace MGPA and measure pulse shapes for different signal sizes
pulse shapes measured with 1ns resolution by sweeping time of charge injection using prog. delay
40 MHz clock and ADC trig.
40 MHz clock and ADC trig.
Cinj
5
Typical non-linearity measurement (1)
-1.0
-0.5
0.0
0.5
1.0
[Vol
ts]
200150100500
time [1 nsec. steps]
1.5
1.0
0.5
0.0
200150100500
time [1 nsec. steps]
subtractpedestals
high gain channel (VFE card)180 pF Cin addedfullscale signal = 5.8 pCsignal sizes not linearly spaced becauseof logarithmic attenuator steps
AD
C ra
nge
5.8 pC
6
1.5
1.0
0.5
0.0
200150100500
time [1 nsec. steps]
2.0
1.5
1.0
0.5
0.0pe
ak s
ampl
e va
lue
[vol
ts]
1.00.80.60.40.20.0
attenuator steps
peak samples fit to peak samples
take peaksamples
and fit
Typical non-linearity measurement (2)pedestal subtracted pulse shapes peak sample vs. attenuator value
1.0 correspondsto 5.8 pC here
7
2.0
1.5
1.0
0.5
0.0
peak
sam
ple
valu
e [v
olts
]
1.00.80.60.40.20.0
attenuator steps
-0.2
-0.1
0.0
0.1
0.2
non-linearity [% fullscale]
peak samples fit to peak samples non-linearity
finally calculate linearity
Non-linearity [% fullscale] =
peak pulse ht. – fit (to pk pulse ht) x 100 fullscale signal (1.8 V)
Typical non-linearity measurement (3)
8
Pulse shape matching
Pulse Shape Matching = (PSMF – Average PSMF) Average PSMF
Average PSMF = average over all pulse shapes
-1.0
-0.5
0.0
0.5
1.0
[Vol
ts]
200150100500
time [1 nsec. steps]
can also calculate pulse shape matching forsame data
PSMF = peak sample value / sample 25ns before
-2
-1
0
1
2
PS
M [%
]
1.00.80.60.40.20.0attenuator steps
9
Some non-linearity results (old)
-0.2
0.0
0.2
6040200
-0.2
0.0
0.2
12840
-0.2
0.0
0.2
6543210
-0.2
0.0
0.2
6040200
-0.2
0.0
0.2
1086420
-0.2
0.0
0.2
6543210
MGPA Version 1 MGPA Version 2
10 chips measured for eachMGPA version
v. similar results V1 cf. V2
nonlinearity within (or close to)± 0.1% specification
these measurements madeon RAL card using simulatedAPD capacitance
Non
linea
rity
[% fu
llsca
le]
Non
linea
rity
[% fu
llsca
le]
charge injected [pC] charge injected [pC]
high gain range
mid
low
mid
low
high
10
-0.2
-0.1
0.0
0.1
0.2
non-
linea
rity
[% fu
llsca
le]
1.00.80.60.40.20.0
attenuator steps
180 pF APD 180 pF, 5 ns risetime
New results
Why is non-linearity worse in H4 beam? (noticeable fall-off for small signals on high gain channel)
Could there be an APD effect?
No – no significant difference between180 pF and APD biased at 350 V
Could signal risetime be shorter than expected?
No - changing charge injection 10ns -> 5ns doesn’t make much difference (at least for high gain channel)
Hi gain channel non-linearity measured on VFE card
11
Final thoughts
non-linearity measured using procedure described here does not explain test beam results results here within or very close to +/- 0.1% spec.
method used here will not include any contribution from ADC, but don’t expect to be significant
could test beam linearity studies be more sensitive to pulse shape?
PSM within design spec. but does tend to show similar trend to test beam linearity plots
-2
-1
0
1
2
PS
M [%
]
1.00.80.60.40.20.0attenuator steps
top related