G2 Exam Prep Test Review Questions with
Correct Answers 2025/2026 Rated A+
Differential Amplifier
G1 (Gate1) =
G2 (Gate2) =
G1 - G2 = - CORRECT ANSWER -____ = *Exploring* electrode
____ = *Reference* electrode
____________ = *Output signal* (calculation)
Common Mode Rejection - CORRECT ANSWER -Ability of a *differential amplifier* to minimize
signals common at both inputs
*Eliminates like components* of an artifact signal common to both inputs
Minimizes artifacts
CMRR =
What does it do? - CORRECT ANSWER -Common mode rejection ratio (CMRR) = *Differential
gain / common mode gain*
-*Higher the CMRR, more efficient the amplifier* (less common mode signal reaches the
output)
-*Minimizes artifact*
, (Not having a patient ground can reduce the effectiveness of CMR; Ground electrode creates
*universal reference* for all scalp) potentials
Signal Pathway - CORRECT ANSWER -1) Electrical signal from patient's body
2) Signal travels from *skin to electrode*
3) Signal transmits from *electrode through lead wire to head box*
4) Signal passes from *head box to differential amplifier* through shielded cable
5) Differential amplifier *subtracts reference signal and ground signal from original signal* using
Common Mode Rejection (set 5K to 10K)
6) New signal to PSG via CAT-5
Filters can be applied; Max electrical leakage allowed is 100 uA
What is recording polarity?
- How calculated?
- Reverse polarity: How? Normally for which channels? - CORRECT ANSWER -- 2 dedicated rows
of inputs (grids): G1 and G2
- G1 - G2 to get the potential difference between 2 input signals
To reverse polarity: reverse inputs *or* change on the PSG software
- Usually only have to do this for EKG or respiratory channels
What does *differential* amplifier do?
What are the common *amplifier controls*, and what do they do? - CORRECT ANSWER --
Multiplies difference between 2 inputs by a common factor called *differential gain*
-Retains difference between two input signals while *subtracting* components simultaneously
*common* to both (*eliminates unwanted signals*)
Correct Answers 2025/2026 Rated A+
Differential Amplifier
G1 (Gate1) =
G2 (Gate2) =
G1 - G2 = - CORRECT ANSWER -____ = *Exploring* electrode
____ = *Reference* electrode
____________ = *Output signal* (calculation)
Common Mode Rejection - CORRECT ANSWER -Ability of a *differential amplifier* to minimize
signals common at both inputs
*Eliminates like components* of an artifact signal common to both inputs
Minimizes artifacts
CMRR =
What does it do? - CORRECT ANSWER -Common mode rejection ratio (CMRR) = *Differential
gain / common mode gain*
-*Higher the CMRR, more efficient the amplifier* (less common mode signal reaches the
output)
-*Minimizes artifact*
, (Not having a patient ground can reduce the effectiveness of CMR; Ground electrode creates
*universal reference* for all scalp) potentials
Signal Pathway - CORRECT ANSWER -1) Electrical signal from patient's body
2) Signal travels from *skin to electrode*
3) Signal transmits from *electrode through lead wire to head box*
4) Signal passes from *head box to differential amplifier* through shielded cable
5) Differential amplifier *subtracts reference signal and ground signal from original signal* using
Common Mode Rejection (set 5K to 10K)
6) New signal to PSG via CAT-5
Filters can be applied; Max electrical leakage allowed is 100 uA
What is recording polarity?
- How calculated?
- Reverse polarity: How? Normally for which channels? - CORRECT ANSWER -- 2 dedicated rows
of inputs (grids): G1 and G2
- G1 - G2 to get the potential difference between 2 input signals
To reverse polarity: reverse inputs *or* change on the PSG software
- Usually only have to do this for EKG or respiratory channels
What does *differential* amplifier do?
What are the common *amplifier controls*, and what do they do? - CORRECT ANSWER --
Multiplies difference between 2 inputs by a common factor called *differential gain*
-Retains difference between two input signals while *subtracting* components simultaneously
*common* to both (*eliminates unwanted signals*)
