BC-535 Preliminary, Rev. 060126
38
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 strength of the signal is
attenuated by 3 dB (10-fold decrease in power). 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 octave.
BLM
– Historically, Black Lipid Membrane from the effect of interference at the upper and lower faces
of the thin film formed resulting in cancellation of all visible wavelengths. When the membrane
thinned appropriately, it would ‘disappear’ or become black. Alternatively, Bilayer Lipid
Membrane. Many researchers now observe membrane formation electrically and have altered the
acronym to mean the molecular bilayer formed from the orientation of lipids such that their polar
heads and hydrophobic fatty acid tails are in register. In an aqueous environment, the polar
heads face away from the membrane leaving the hydrophobic domains within the bilayer.
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.
Warner
Instruments
A Harvard Apparatus Company .