Multichannel Systems STG4002 Manual - Manual (Page 81)

Analog Output Signals
77
Resistance dependency of rise time
The higher the load resistance, the higher will be the rise time. The rise time (10 % / 90 %)
was measured with increasing load resistances and a constant current amplitude of 50 μA.
For 50 μA pulses, the relationship is linear up to the maximum load resistance (Please see
"Current Mode") as shown by the following curve. Not shown are the results of the same
measurement under the same conditions, except of the amplitude with a constant current
amplitude of 100 μA. Up to a load resistance of 450 k
, the results are congruent with
50 μA amplitude.

Stimulus output comparison
The following figures are examples for demonstrating how the amplitude and resistance
will affect the kinetics of a current pulse. These images document also that in contrast to
the current mode, in voltage mode, the rise time is constant and not dependent on the
amplitude or load resistance.
The graphs were generated by a standard oscilloscope. The devices were set up according to
the recommendations under "Voltage Mode" and "Current Mode". The same pulse protocol
and the same channel number of the STG outputs were used for measuring the voltage and
the current output.