The core of the LMP91000 is a potentiostat circuit. It consists
of a differential input amplifier used to compare the potential
between the working and reference electrodes to a required
working bias potential (set by the Variable Bias circuitry).
The error signal is amplified and applied to the counter electrode
(through the Control Amplifier - A1). Any changes in
the impedance between the working and reference electrodes
will cause a change in the voltage applied to the
counter electrode, in order to maintain the constant voltage
between working and reference electrodes. A Transimpedance
Amplifier connected to the working electrode,
is used to provide an output voltage that is proportional to the
cell current. The working electrode is held at virtual ground
(Internal ground) by the transimpedance amplifier. The potentiostat
will compare the reference voltage to the desired
bias potential and adjust the voltage at the counter electrode
to maintain the proper working-to-reference voltage.