The typical transfer characteristics of a transistor in CE configuration is shown in figure. A load resistor of \(2\) \(kΩ\) is connected in the collector branch of the circuit used. The input resistance of the transistor is \(0.50\) \(kΩ\). The voltage gain of the transistor is ________.
Correct Answer: 200
Solution and Explanation
\(V_{gain} = \text{Current gain} \times \frac{R_L}{R_t}\)
= \(\frac{ΔI_c}{ΔI_B} \times \frac{R_L}{R_t}\)
= \(\frac{5 \times 10^{-3}}{100 \times 10^{-6}} \times\frac{ 2 \times 10^3}{0.5 \times 10^3}\)
= \(\frac{10}{0.5} \times 10 \)
= \(200\)
Top Questions on Transistors
In the circuit shown, the identical transistors Q1 and Q2 are biased in the active region with \( \beta = 120 \). The Zener diode is in the breakdown region with \( V_Z = 5 \, V \) and \( I_Z = 25 \, mA \). If \( I_L = 12 \, mA \) and \( V_{EB1} = V_{EB2} = 0.7 \, V \), then the values of \( R_1 \) and \( R_2 \) (in \( k\Omega \), rounded off to one decimal place) are _________, respectively.
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- The electron mobility \( \mu_n \) in a non-degenerate germanium semiconductor at 300 K is 0.38 m$^2$/Vs. The electron diffusivity \( D_n \) at 300 K (in cm$^2$/s, rounded off to the nearest integer) is _________.
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Concepts Used:
Transistors
Transistor
A transistor is a type of semiconductor device that can be used to both conduct and insulate electric current or voltage. A transistor basically acts as a switch and an amplifier. In simple words, we can say that a transistor is a miniature device that is used to control or regulate the flow of electronic signals.
Parts of a Transistor:
A transistor is a combination of three terminals made of semiconducting materials that help in making a connection to an external circuit and allow current to flow. The three terminals are:
- Base: The base activates the transistor. It is thin and lightly doped. It is put in the centre of the transistor.
- Emitter: The emitter is the negative terminal of the transistor. It is heavily doped and is moderately sized.
- Collector: The collector is the negative terminal of the transistor. It is located on the right side of a transistor and is moderately doped. It is larger than the emitter.
Read More: Difference Between NPN and PNP Transistor
Types of Transistors:
A transistor is a type of electronic device which is formed by p-type and n-type semiconductors.
NPN Transistor
- NPN transistor is a type of Bipolar Junction Transistor.
- In this, electrons are major current carriers, and minor ones are holes.
- Their arrangement is in such a way that N-type doped semiconductors are separated by the layer of P-type doped semiconductors which is a thin layer of material embedded between them.
- Emitter Current = Collector Current + Base Current
PNP Transistor
- PNP transistor is also a type of Bipolar Junction Transistor.
- In these, holes are the major source that carries current, and electrons are minor.
- Their arrangement is in a way that P-type doped semiconductor is separated by N-type doped semiconductor material which is a thin layer.
- Emitter Current = Collector Current + Base Current
Read More: Characteristics of a Transistor
Configurations of a Transistor:
Using the three types of configuration can be used to design any transistor circuit. The three types of configuration of a transistor are:
- Common Emitter Transistor
- Common Base Transistor
- Common Collector Transistor
Common Emitter (CE) Configuration of a Transistor
In Common Emitter Configuration, the transistor’s emitter terminal will be connected common between the output terminal and the input terminal.
Input Characteristics
- Variation of emitter current (IB) with Base-Emitter voltage (VBE) when Collector-Emitter voltage (VCE) is held constant.
- Rin = ΔVBE/ΔIB | VCE = Constant
Output Characteristics
- Variation of collector current (IC) with Collector-Emitter voltage (VCE) when the base current (IB) is held constant.
- Rout = ΔVCE/ΔIC | IB = Constant
Current Transfer Characteristics
- The variation of the collector current (IC) with the base current (IB) when the collector-emitter voltage (VCE) is constant.
- α = ΔIC/ΔIB | VCB = Constant
Common Base (CB) Configuration of a Transistor
In Common Base Configuration, the transistor’s base terminal will be connected common between the output terminal and the input terminal.
Input Characteristics
- Variation of emitter current (IE) with Base-Emitter voltage (VBE) when the Collector Base voltage (VCB) is held constant.
- Rin = ΔVBE/ΔIE | VCB = Constant
Output Characteristics
- Variation of collector current (IC) with Collector-Base voltage (VCB) when the emitter current (IE) is held constant.
- Rout = ΔVCB/ΔIB | IE = Constant
Current Transfer Characteristics
- The variation of the collector current (IC) with the emitter current (IE) when the Collector Base voltage (VCB) is constant.
- α = ΔIC/ΔIE | VCB = Constant
Common Collector Configuration of a Transistor
In Common Collector Configuration, the transistor’s collector terminal will be connected common between the output terminal and the input terminal.
Input Characteristics
- Variation of emitter current (IB) with Collector-Base voltage (VCB) when the Collector Base voltage (VCB) is held constant.
Output Characteristics
- Variation of emitter current (IE) with Collector-Emitter voltage (VCE) when the base current (IB) is held constant.
Current Transfer Characteristics
- The variation of the collector current (IE) with the base current (IB) when the Collector-Emitter voltage (VCE) is constant.