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ral109gain.txt
Edinburgh/RAL RAL109 Shaping Amplifier Module
---------------------------------------------
Gain
----
The gain of the RAL109 shaping amplifier modules is adjusted by
attenuating the input signal.
The `gain resistors' are two dual inline (DIL) 16-pin packages. Each DIL
package contains eight individual resistors. The DIL packages are located
between the power and input signal connectors at the back of the RAL109
PCB motherboard.
The `termination resistors' are two single inline (SIL) 8-pin packages.
Each SIL package contains four individual resistors. The SIL packages
are located adjacent to the `gain resistors'. Input signals are typically
terminated in 100 Ohm. Because the output impedance of the RAL108 charge
sensitive preamplifiers is 100 Ohm, removal of the `termination resistors'
results in an effective x2 increase in gain. It should be noted that n+n
ohmic strip channels _require_ the 100 Ohm `termination resistors' to
be replaced by 1 kOhm `termination resistors' - p+n junction strip
channels do _not_ require any `termination resistors'.
Examples of gain settings for the RAL109 shaping amplifier module are
shown in the table below.
With (100 Ohm) input termination
--------------------------------
gain [V/MeV] = 0.45 / ( 1 + R [kOhm] )
R gain 9.375V FSR 7.500V FSR 3.840V FSR min. LLD
[kOhm] [V/MeV] [MeV] [MeV] [MeV] [keV]
0.022 0.440 21.3 17.1 8.7 300
1 0.225 41.7 33.3 17.1 600
2.2 0.141 66.5 53.2 27.2 1000
3.3 0.105 89.3 71.4 36.6 1300
4.7 0.079 119 94.9 48.6 1800
5.6 0.068 138 110 56.5 2100
6.8 0.058 162 129 66.2 2400
8.2 0.049 191 153 78.4 2900
10 0.041 229 183 93.7 3400
Without (100 Ohm) input termination
-----------------------------------
gain [V/MeV] = 0.9 / ( 1 + R [kOhm] )
R gain 9.375V FSR 7.500V FSR 3.840V FSR min. LLD
[kOhm] [V/MeV] [MeV] [MeV] [MeV] [keV]
0.022 0.880 10.7 8.5 4.4 150
1 0.450 20.9 16.7 8.6 300
2.2 0.282 33.2 26.6 13.6 500
3.3 0.210 44.6 35.7 18.3 650
4.7 0.158 59.3 47.5 24.3 900
5.6 0.136 68.9 55.2 28.3 1050
6.8 0.116 80.8 64.7 33.1 1200
8.2 0.098 95.7 76.5 39.2 1450
10 0.082 114 91.5 46.9 1700
Notes:
------
1) minimum LLD corresponds to c. 10mV (front panel monitor) for RAL109s
with 100 Ohm input termination.
2) minimum LLD corresponds to c. 20mV (front panel monitor) for RAL109s
without 100 Ohm input termination.
3) 9.375V FSR corresponds to the maximum input signal amplitude of the
Silena 4418/V CAMAC ADC.
3) 7.500V FSR corresponds to the maximum input signal amplitude of the
Silena 9418/6V VME ADC.
4) 3.840V FSR corresponds to the maximum input signal amplitude of the
CAEN V785 A[A-D] VME multievent ADC with sliding scale enabled.
5) The gain values quoted are nominal. Typical variation of overall
gain of RAL108 charge-sensitive preamplifier and RAL109 shaping
amplifier is +/-10%.
Gain Adjustment
---------------
N.B. SWITCH OFF POWER TO THE KM-6 SUB-RACK BEFORE INSERTION OR REMOVAL
OF RA1L09 SHAPING AMPLIFIER MODULES
1) Determine appropriate value for `gain resistors' using the tables
and the information above.
The resistance value of the DIL/SIL packages is usually presented
as follows: R22, R4K7 etc. or 220 (i.e. 22 x 10^0), 472 (i.e. 47 x
10^2) etc. for 22 ohm and 4.7 kohm respectively.
2) Determine whether you wish to terminate the input signals.
3) Switch off power to the KM-6 sub-rack containing the RAL109 shaping
amplifier module.
4) Remove RAL109 shaping amplifier module.
5) Using a fine screwdriver (or similar) _gently_ lever the DIL packages
at each end until free of their DIL sockets.
6) Remove `termination resistors' if required.
6) Insert `termination resistors' if required.
Note that the SIL packages have no particular orientation.
7) Insert new DIL packages into their DIL sockets
Note that the DIL packages have no particular orientation.
8) Visual check for bent pins or incorrectly seated DIL/SIL packages.
9) Insert RAL109 shaping amplifier module.
10) Switch on power to KM-6 sub-rack.
T.Davinson - April 2004
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