ABRET R.EEG.T Study Guide - EEG
Instrumentation
What is the definition of a differential amplifier? - answer Amplifies only the difference in
voltage between two inputs. Does not amplify equal voltages at two inputs. The more
the inputs are different the more there is to amplify.
What is the definition of Input Impedance? - answer NOT the impedance between the
scalp and the electrodes
An impedance between components of the differential amplifier. It must be HIGH for
optimal functioning of the amplifier. Must be at lease 10 mega ohms
What is the definition of of common mode rejection? - answer A metric used to quantify
the ability of the device to reject common-mode signals, i.e. those that appear
simultaneously and in-phase on both inputs.
Rejects external interference such as 60 Hz and radio frequencies by canceling signals
common to both inputs.
The CMRR should be at least 80dB or 10,000:1
The rule in the design of EEG instruments is that if input 1 is positive with respect to
input 2 the deflection of the channel will be? - answerDown
The rule in the design of EEG instruments is that if input 1 is negative with respect to
input 2 the deflection of the channel will be? - answerUp
What is the definition of gain? - answerGain is the ratio of the output signal.
Gain has no unit of measure.
What is the definition of Sensitivity? - answerThe ratio of input voltage to output
deflection.
Equation: S-V/A
What is the definition of filter? - answerUsed to exclude waveforms that are out of range
so that the waveforms of most importance (1-30 Hz) can be recorded without distortion
What is the definition of amplifier? - answerA differential amplifier amplifies only the
difference in voltage between two inputs.
It does not amplify equal common voltages at the two inputs. The differential amplifier
rejects external interference such as 60 hz and radio frequencies by canceling signals
common to both inputs
Instrumentation
What is the definition of a differential amplifier? - answer Amplifies only the difference in
voltage between two inputs. Does not amplify equal voltages at two inputs. The more
the inputs are different the more there is to amplify.
What is the definition of Input Impedance? - answer NOT the impedance between the
scalp and the electrodes
An impedance between components of the differential amplifier. It must be HIGH for
optimal functioning of the amplifier. Must be at lease 10 mega ohms
What is the definition of of common mode rejection? - answer A metric used to quantify
the ability of the device to reject common-mode signals, i.e. those that appear
simultaneously and in-phase on both inputs.
Rejects external interference such as 60 Hz and radio frequencies by canceling signals
common to both inputs.
The CMRR should be at least 80dB or 10,000:1
The rule in the design of EEG instruments is that if input 1 is positive with respect to
input 2 the deflection of the channel will be? - answerDown
The rule in the design of EEG instruments is that if input 1 is negative with respect to
input 2 the deflection of the channel will be? - answerUp
What is the definition of gain? - answerGain is the ratio of the output signal.
Gain has no unit of measure.
What is the definition of Sensitivity? - answerThe ratio of input voltage to output
deflection.
Equation: S-V/A
What is the definition of filter? - answerUsed to exclude waveforms that are out of range
so that the waveforms of most importance (1-30 Hz) can be recorded without distortion
What is the definition of amplifier? - answerA differential amplifier amplifies only the
difference in voltage between two inputs.
It does not amplify equal common voltages at the two inputs. The differential amplifier
rejects external interference such as 60 hz and radio frequencies by canceling signals
common to both inputs
