Multichannel Systems STG4002 Manual - Manual (Page 80)

Stimulus Generator 4002 Manual
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11.5
Rise Time
The rise time of the voltage output is constant and independent from the stimulus protocol.
The rise time of the current output is no fixed hardware property. The kinetics depend on
the amplitude of the current pulse and the load resistance, that is, generally the electrode
impedance. The resistance affects the kinetics much stronger than the amplitude.
Generally, this does not make much difference for biological applications. If you have very
time-critical applications, or if you use very short pulses, you should check the output
of the STG with an oscilloscope before starting the experiment.
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.