All Exams Test series for 1 year @ ₹349 only
Question

For a single stage transistor amplifier, the collector load R c= 2 kΩ and the input resistance R i= 1 kΩ. If the current gain is 50, calculate the voltage gain of the amplifier.

The correct answer is

100

This question asks us to calculate the voltage gain ($A_v$) of a single-stage transistor amplifier given specific parameters: the collector load resistance ($R_C$), the input resistance ($R_i$), and the current gain ($A_i$).

Understanding Amplifier Parameters

  • Collector Load ($R_C$): This is the resistance connected in the collector circuit of the transistor, which determines the output voltage swing. Given as $R_C = 2 \text{ k}\Omega$.
  • Input Resistance ($R_i$): This is the effective resistance seen at the input terminals of the amplifier stage. Given as $R_i = 1 \text{ k}\Omega$.
  • Current Gain ($A_i$): This is the ratio of the output current to the input current. Given as $A_i = 50$.
  • Voltage Gain ($A_v$): This is the ratio of the output voltage to the input voltage. This is what we need to calculate.

Calculating Voltage Gain

The voltage gain ($A_v$) of a common-emitter transistor amplifier (or a similar single-stage amplifier) can be calculated using the following formula:

$$A_v = A_i \times \frac{R_L}{R_i}$$

Where:

  • $A_v$ is the voltage gain.
  • $A_i$ is the current gain.
  • $R_L$ is the load resistance. In this case, the collector load $R_C$ acts as the load resistance, so $R_L = R_C$.
  • $R_i$ is the input resistance.

Applying the Formula

Let's substitute the given values into the formula:

  • $A_i = 50$
  • $R_L = R_C = 2 \text{ k}\Omega$
  • $R_i = 1 \text{ k}\Omega$

Now, we calculate the voltage gain:

$$A_v = 50 \times \frac{2 \text{ k}\Omega}{1 \text{ k}\Omega}$$ $$A_v = 50 \times 2$$ $$A_v = 100$$

Result

The calculated voltage gain of the single-stage transistor amplifier is 100. This corresponds to the first option.

Was this answer helpful?

Important Questions from Bipolar Junction Transistors

  1. For a common emitter connection of BJT, find the value of β if α = 0.995

  2. Which represents the Transport Factor of BJT?
  3. For a bipolar junction transistor in common emitter mode, IC = maximum and VC (collector voltage) = VE (emitter voltage), the transistor operates in _____ mode.

  4. High frequency transistors are designed especially for:

  5. For an ideal transistor, the reverse parameters (h o& h r) are
Need Expert Advice?

Start Your Preparation with Prepp Mobile App

Download the app from Google Play & App Store
Download the app from Google Play & App Store
Prepp Mobile App