Glossary
A/D converter – Analog to Digital converter. Computers are inherently digital while the voltage or current
output from an amplifier is analog. Therefore, a signal must be first converted to a digitized form before
a computer or its software can accept it. Desirable features in an A/D converter include rapid signal
conversion, small-step resolution and low noise.
analog – Continuous or non-discrete. Often dynamically varying. Compare to: digital.
bandwidth – The range of frequencies a device is capable of processing with minimal distortion. A
bandwidth of 1 Hz indicates that the device can faithfully process a signal occurring once per second
(1 Hz). The larger the bandwidth, the faster the device.
Bessel filter – A device used to attenuate the high frequency components of a signal. The cutoff frequency
of a filter is normally defined as the frequency at which the amplitude of the signal is attenuated by 3
dB. A higher order filter (i.e., 8-pole vs. 4-pole) will attenuate the high frequency components more
rapidly. An 8-pole Bessel filter attenuates at 14 dB per octive.
BNC connector – A type of connector used to connect coaxial cables to high frequency electronic
equipment.
CAP COMP – See: capacity compensation.
capacitance – A capacitor can be represented by a small break in a conducting pathway bounded by two
parallel plates. The electric field generated across the space between the plates in the presence of an
applied voltage maintains a charge density on each plate. The numerical measure of a capacitor’s
ability to maintain charge separation at a given potential is its capacitance. Capacitors effectively block
DC currents while passing AC currents. Has units of Farad (F).
capacity compensation – The process wherein the current generated when charging a capacitor is
subtracted (or compensated) from the output signal.
channel conductance – See: unitary channel conductance
chassis ground – A connection used to link the amplifier chassis to an external potential.
circuit ground – The potential to which all other potentials within the circuit are referenced. Also, a
connection used to link the reference potential of the amplifier circuit to an externally defined potential.
CMD IN – Command Input. An external input into the amplifier allowing the application of user defined
command voltages to the headstage. Connection is usually via BNC.
command sensitivity – Selectable scaling of CMD IN input. Attenuation values of CMD IN are x0.1, x0.01,
and x0.001.
command voltage – The voltage applied to the headstage resulting in a desired transmembrane potential
in the system under study.
control blocks – Organization of controls on the amplifier into functional groups. Blocks are delineated by
titled blue boundaries.
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