Multichannel Systems STG4004+STG4008 Manual - Manual (Page 82)

Stimulus Generator 4000 Series Manual
78
Amplitude dependency of rise time
The rise time is independent from the current amplitude in the common range of amplitudes..
The rise time (10 % /90 %) was measured with increasing current amplitudes (100 μA to 1600 μA)
and a constant load resistance of 10 k
. The output current is nearly constant up to amplitudes
of 1100 μA, but increases about 0.3 μs until the maximum of 1600 μA amplitude is reached.
The relationship is not linear as shown by the following curve.
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.