Advertisements
Advertisements
प्रश्न
With the help of a neat circuit diagram, explain the transistor as an amplifier?
Advertisements
उत्तर
Working of an amplifier:
- The circuit of an amplifier using an n-p-n transistor in CE configuration is shown in the figure.
- When the input voltage Vin is not applied, applying the Kirchhoff’s law to the output loop, we can write, VCC = VCE + ICRL
- Similarly, for input loop,
VBB = VBE + IBRB - When the input AC signal is applied, Vin is not zero. Thus, the voltage drop across the input loop will now be,
VBB + Vin = VBE + IBRB + ΔIB (RB + ri) ....(1) - The AC signal applied adds the current of ΔIB to the original current flowing through the circuit. Therefore, the additional voltage drop in the input loop will be across resistor RB (= ΔIBRB) and across the input dynamic resistance of the transistor (= ΔIBri).
- From equation (1),
Vin = ΔIB (RB + ri)
As, RB is very small, we can consider,
Vin = ΔIBri - The changes in the base current IB cause changes in the collector current IC. This changes the voltage drop across the load resistance because VCC is constant. We can write,
ΔVCC = ΔVCE + RLIC = 0
∴ ΔVCE = -RLIC - The change in the output voltage ΔVCE is the output voltage Vo hence we can write,
Vo = ΔVCE = `beta`ACRLΔIB
APPEARS IN
संबंधित प्रश्न
In a BJT, the largest current flow occurs ______.
Derive the relation between α and β.
Which method of biasing is used for operating a transistor as an amplifier?
In a common base configuration, the transistor has an emitter current of 10 mA and a collector current of 9.8 mA. The value of base current is ______
In a transistor amplifier, IC = 5.5 mA , IE = 5.6 mA. The current amplification factor β is ______
With the help of a neat diagram, explain the working of the npn transistor?
The principle based on which a solar cell operates is ____________.
The light emitted in an LED is due to
The output of the following circuit is 1 when the input ABC is
Explain the need for a feedback circuit in a transistor oscillator.
What is rectification?
A transistor of α = 0.99 and VBE = 0.7 V is connected in the common-emitter configuration as shown in the figure. If the transistor is in the saturation region, find the value of collector current.
Least doped region in a transistor ____________.
In the study of transistor as an amplifier, the ratio of collector current to emitter current is 0.98 then the ratio of collector current to base current will be ______.
Ve, Vb, and Ve are emitter, base, and collector voltage respectively for npn transistor in CE mode. Amplifier works for the combination of biasing voltage equal to ______.
If `alpha`-current gain of a transistor is 0.98. What is the value of `beta`- current gain of the transistor?
In an npn transistor, the collector current is 24 mA. If 80% of electrons reach collector, its base current in mA is ______.
In a transistor in CE configuration, the ratio of power gain to voltage gain is ____________.
Which of the following regions of a transistors are, respectively, heavily dopped and lightly dopped?
In a common emitter amplifier circuit using an n-p-n transistor, the phase difference between the input and the output voltages will be: ____________.
In a silicon transistor, a change of 7.89 mA in the emitter current if produces a change of 7.8 mA in the collector current, then the base current must change by ____________.
In a transistor, the thickness of the base region ____________.
For an ideal diode, the current in the following arrangement is ______.
A conducting wire has length 'L1' and diameter 'd1'. After stretching the same wire length becomes 'L2' and diameter 'd2' The ratio of resistances before and after stretching is ______.
The reverse bias in a junction diode is changed from 8V to 13V, then the value of the current changes from 40μA to 60μA. The resistance of junction diode will be ______.
In a CE amplifier, the current gain is 80 and the emitter current is 9 mA. The base current is ______.
Define peak value of alternating signal.
