Surface Concept Preamplifier-CFD, Manual

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The Asymmetry between the inverted input signal and the original input signal can be adjusted by turning 

the corresponding potentiometer (marked “Asy” on the front panel). The fraction of the positive pulse is 

getting larger, when turning the potentiometer counterclockwise.

4.3.3 Adjustment of the Asymmetry

4.3.4 Procedure for Walk Minimization

The following description gives a procedure of how to minimize the walk for a given amplitude range:

1.  Select the amplitude range of pulses, which should be measured (e.g. -60mV to -600mV).
2.  Apply pulses of max. Amplitude (within the amplitude range) to the Input of the CFD (e.g. -600mV).
3.  Observe the CFD output signal with an oscilloscope and trigger on the falling edge of the output signal.
4.  Check the CFD walk by changing the amplitude of the input signal by around 50% (e.g. changing     

between -300 and -600mV) and minimize the CFD walk by adjusting the asymmetry.

5.  Decrease the amplitude of the input signal by at least 50% (e.g. down to -300mV) and check the CFD 

walk for small pulse amplitudes by changing the amplitude of the input signal again (e.g. changing 

between -50 and -300mV).

6.  Minimize the CFD walk for small pulses by adjusting the zero offset.

4.4  Power Requirements

The 1-Channel Preamplifier-CFD is supplied by a wall power supply (input: 100 – 240V, 50 – 60Hz, 1.0A 

max) with a maximum output of 15W (+5V, 3A).

Figure 4: View of 5 Pin housing connector of 1-Channel Preamplifier-CFD 

from outside.