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Examples
Transient Noise Analysis Example 1—High-Rate Particle Detector
Figure 21-43. High-Rate Particle Detector Circuit
Description of the Particle Detector Behavior
The pre-amplifier has a rise time of less than 20ns and a large fall time constant compared to the
rise time. Therefore, for this application it can be considered as an integrator. The function of
the analog memory port is signal storage and noise shaping. It takes successive samples of the
signal into the different feedback capacitors. The complete system of analog memories acts as a
charge sampler and is equivalent, from a signal processing point of view, to a discrete
differentiator.
Figure 21-44 shows the signal at the input, the voltage at the amplifier output, and the signal at
the output of the complete system. The simulation was performed for an input charge of 2.5 fC
across a 5pF input capacitor and with a 15ns clock period.
The clock of the analog memory port is synchronized with the input signal to store the
maximum amount of charge in the first feedback capacitor. Note that most of the charge is
deposited in one storage capacitor within the 15ns clock period.
Eldo® User's Manual, 15.3 1369