Reference Section
•
67
Chapter 5
Capacitance Compensation
•
Used to compensate electrode and cell capacitance when in V-Clamp mode.
•
Electrode capacitance is compensated using the
controls in the V-Clamp
pane.
•
Cell capacitance is compensated by checking the
checkbox and
using the associated controls in the V-Clamp pane.
•
See also
External Command Inputs, Series Resistance Compensation.
Electrode Capacitance Compensation
When a voltage-clamp step is applied to an electrode, the clamp must provide a spike
of current at the start (and finish) of the step to charge (and discharge) the capacitance
of the electrode (C
p
). The main problem with these spikes is that they may saturate the
headstage circuit or later circuits, leading to distortion of the signals of interest.
Injecting into the input of the headstage a current that directly charges the electrode
capacitance, bypassing the normal voltage clamp circuitry, solves this problem. Thus,
when the compensation is correctly adjusted, the charge and discharge of the electrode
capacitance is invisible to the user.
