CR-200 Datasheet, PDF (1/2 Pages) List of Unclassifed Manufacturers – Gaussian shaping amplifier

CR-200 Gaussian shaping amplifier (Rev. 2):
application guide
General Description
The CR-200 is a single channel shaping amplifier, intended to be used
to read out the signals from charge sensitive preamplifiers (e.g. Cremat
CR-110 or equivalent). Gaussian shaping amplifiers (also known as
pulse amplifiers, linear amplifiers, or spectroscopy amplifiers) accept a
step-like input pulse and produce an output pulse shaped like a
Gaussian function. The purposes of this are to filter much of the noise
from the signal of interest and to provide a quickly restored baseline to
allow high counting rates. The CR-200 is available in 4 different
shaping times: 100 ns, 250 ns, 1 s, and 4 s. Each has a fixed gain of
10. If additional gain is desired, it is recommended that this be done
with the application of an additional amplifier between the preamplifier
and the CR-200 shaping amplifier. Cremat offers an evaluation board
(CR-160) which includes a variable gain amplifier of appropriate
bandwidth, as well as all necessary connectors.
100 mV
input pulse shape
output pulse shape
1.0 V
Figure 1. Comparison of sample input and output pulse shapes
Improvements in Revision 2
The new CR-200 'Revision 2' has been improved with a significant
reduction in power consumption, reduced output offset, and an
improved thermal coefficient of output offset. Revision 2 is pin-for-pin
compatible with the previous revision of CR-200, however it should be
noted that the labeling has been changed so that pin 1 appears on the
left side of the label.
Definition of "Shaping Time"
The shaping time is defined as the time-equivalent of the "standard
deviation" of the Gaussian output pulse. A simpler measurement to
make in the laboratory is the full width of the pulse at half of it's
maximum value (FWHM). This value is greater than the shaping time
by a factor of 2.35. For example, a Gaussian shaping amplifier with a
shaping time of 1.0 s would have a FWHM of 2.35 s.
Pole/Zero Correction
The decay time of the input pulse creates an offset in the baseline of
the output pulse unless a pole/zero correction is utilized. This can be
done by connecting a resistor between pin 1 (input) and pin 2 (P/Z). If
the CR-200 is used to read out the Cremat CR-110 preamplifier, then
this resistor value should be 300 k (CR-200-100ns), 130 k (CR-200-
250ns and CR-200-1 s), and 43 k (CR-200-4 s). If a different
preamplifier is used, then the resistor value should be chosen so that it
is equal to the decay constant (RC) of the preamplifier pulse divided by
the CR-200 shaping amplifier input capacitor Cin (see table).
Package Specifications
The CR-200 circuit is contacted via an 8-pin SIP connection (0.100"
spacing). Pin 1 is marked with a white dot for identification.
0.88"
0.14"
0.85"
Cremat, Inc.
CR-200
Rev.2
1 2 34 5 6 7 8
Figure 2.
Equivalent circuit diagram
Figure 3 shows an equivalent circuit. Pin numbers corresponding with the CR-200
preamplifier are shown. Input components Cin and Rin form a differentiating circuit. The
following circuitry consists of two Sallen and Key filters, providing 4 poles of integration
and signal gain. The numerous integration stages produce an output pulse that
approximates a Gaussian function.
Cin
1
8
2
Rin
3, 6, 7
Figure 3.
part number
CR-200-100ns
CR-200-250ns
CR-200-1 s
CR-200-4 s
Cin
470 pF
1000 pF
1000 pF
3300 pF
Rin
220
240
1.0 k
1.2 k
shaping time
100 ns
250 ns
1.0 s
4.0 s
Typical Application
Figure 4 shows the CR-200 in a typical application, coupled to a detector via a CR-110
charge sensitive preamplifier. Depending on the requirements of your application, an AC-
coupled amplifier may be added between the preamplifier and shaping amplifier to further
increase the signal size.
Det bias
filtered bias
detector
input
charge preamplifier
CR-110
12345678
shaping amplifier
broadband amplifier
CR-200
12345678
+Vpower
P/Z
-Vpower
Figure 4.
output
+Vpower
-Vpower
Assume temp =20˚C, Vs = 9V, unloaded output
CR-200
units
amplification channels
gain
polarity
operating temperature range
input noise voltage
CR-200-100ns
CR-200-250ns
CR-200-1 s
CR-200-4 s
output impedance
output offset
output temperature coefficient
power supply voltage (Vs)
maximum
minimum
power supply current
maximum output current (with loaded output)
maximum output swing
1
10
non-inverting
-40 C to 85 C
90
90
45
30
<5
-20 to +20
-60 to +60
V RMS
V RMS
V RMS
V RMS
mV
V/ C
V_s = 12
Vs = 6
7
10
8.5
volts
volts
mA
mA
volts