1 Exampromax - Stuvia US 2025/2026
Small Signal Analysis in Transistor Amplifiers
Questions and Answers (100% Correct
Answers) Already Graded A+
Transistor small-signal amplifiers
Ans: Can be considered to operate linear for most applications, permitting the use
of the superposition theorem to isolate the dc analysis from the ac analysis.
Model (ac-modelling)
Ans: A combination of circuit elements, properly chosen, that best approximates
the actual behaviour of a semiconductor device under specific operating
conditions.
© 2025 Assignment Expert
Exampromax - Stuvia US
Two-port model
Ans: Used to define the equivalent circuit for BJT's or FET's, consisting of two
pairs of terminals: an input side for the signal and an output side for the load.
Input impedance (Zi)
Ans: Defined as Zi = Vi / Ii, and can vary from a few ohms to megohms
depending on the transistor usage.
Output impedance (Zo)
Ans: Determined at the output terminals looking back into the system with the
applied voltage set to zero, defined as Zo = Vo / Io.
No-load voltage gain (Av(NL))
Ans: Defined by Av(NL) = Vo / Vi when no load is connected to the output
terminals.
Voltage Gain (Av)
Ans: Defined as Av = Vo / Vi.
Current Gain (Ai)
Ans: Defined as Ai = Io / Ii, typically ranging from just less than 1 to exceeding
100 for BJT amplifiers.
, 2 Exampromax - Stuvia US 2025/2026
Voltage ratio in decibel
Ans: The voltage ratio in decibel between points A and B with no load connected
is -6.02 dB.
RMS voltage between A and B
Ans: 80mV RMS when R1 is 200 Ω, changes to 120 mV RMS when R1 is an
open circuit.
Peak voltage of Vs1
Ans: Determined to be 169.7 mV.
RMS voltage with R1 equal to 400 Ω
© 2025 Assignment Expert
Ans: The voltage between A and B with R1 as 400 Ω is to be determined, with
Vs1 and rs unchanged.
Exampromax - Stuvia US
Output voltage (Vo)
Ans: In the context of Ai, defined as Io = -Vo / RL.
Input voltage (Vi)
Ans: In the context of Ai, defined as Ii = Vi / Zi.
Resistance (Rsource)
Ans: The effect of the source resistance in the voltage gain equation is determined
by Vi = Zi.Vs / (Zi + Rs).
Resistance (rs)
Ans: Given as 100Ω.
Load resistor (RL)
Ans: Given as 500 Ω.
Internal resistance (rs)
Ans: Given as 1000 Ω.
Voltage between C and D
Small Signal Analysis in Transistor Amplifiers
Questions and Answers (100% Correct
Answers) Already Graded A+
Transistor small-signal amplifiers
Ans: Can be considered to operate linear for most applications, permitting the use
of the superposition theorem to isolate the dc analysis from the ac analysis.
Model (ac-modelling)
Ans: A combination of circuit elements, properly chosen, that best approximates
the actual behaviour of a semiconductor device under specific operating
conditions.
© 2025 Assignment Expert
Exampromax - Stuvia US
Two-port model
Ans: Used to define the equivalent circuit for BJT's or FET's, consisting of two
pairs of terminals: an input side for the signal and an output side for the load.
Input impedance (Zi)
Ans: Defined as Zi = Vi / Ii, and can vary from a few ohms to megohms
depending on the transistor usage.
Output impedance (Zo)
Ans: Determined at the output terminals looking back into the system with the
applied voltage set to zero, defined as Zo = Vo / Io.
No-load voltage gain (Av(NL))
Ans: Defined by Av(NL) = Vo / Vi when no load is connected to the output
terminals.
Voltage Gain (Av)
Ans: Defined as Av = Vo / Vi.
Current Gain (Ai)
Ans: Defined as Ai = Io / Ii, typically ranging from just less than 1 to exceeding
100 for BJT amplifiers.
, 2 Exampromax - Stuvia US 2025/2026
Voltage ratio in decibel
Ans: The voltage ratio in decibel between points A and B with no load connected
is -6.02 dB.
RMS voltage between A and B
Ans: 80mV RMS when R1 is 200 Ω, changes to 120 mV RMS when R1 is an
open circuit.
Peak voltage of Vs1
Ans: Determined to be 169.7 mV.
RMS voltage with R1 equal to 400 Ω
© 2025 Assignment Expert
Ans: The voltage between A and B with R1 as 400 Ω is to be determined, with
Vs1 and rs unchanged.
Exampromax - Stuvia US
Output voltage (Vo)
Ans: In the context of Ai, defined as Io = -Vo / RL.
Input voltage (Vi)
Ans: In the context of Ai, defined as Ii = Vi / Zi.
Resistance (Rsource)
Ans: The effect of the source resistance in the voltage gain equation is determined
by Vi = Zi.Vs / (Zi + Rs).
Resistance (rs)
Ans: Given as 100Ω.
Load resistor (RL)
Ans: Given as 500 Ω.
Internal resistance (rs)
Ans: Given as 1000 Ω.
Voltage between C and D
