S. L. Arora Solutions for Chapter: Semiconductor Devices and Digital Circuits, Exercise 4: Problems For Practice

The power gain for $\mathrm{C}\mathrm{B}$ amplifier is $800,$ and the voltage amplification factor is $840.$ Find the collector current when the base current is $1.2 \mathrm{m}\mathrm{A}$.

The current gain of a transistor in CB configuration is $0.98.$ Find the change in collector current corresponding to a change of $5.0 \mathrm{m}\mathrm{A}$ in the emitter current. What would be the change in base current?

In common‐emitter transistor amplifier, the load resistance of the output circuit is $1000$ times the load resistance of the input circuit. If $\mathrm{\alpha }=0.98$, then calculate the voltage gain.

In common‐emitter transistor amplifier, an increase of $50 \mathrm{\mu }\mathrm{A}$ in the base current causes an increase of $1.0 \mathrm{m}\mathrm{A}$ in the collector current. Calculate gain $\mathrm{\beta }$. What will be the change in emitter current? Also calculate current gain $\mathrm{\alpha }.$

The base current of a transistor is $105 \mathrm{\mu }\mathrm{A}$ and collector current is $2.05 \mathrm{m}\mathrm{A}.$ (i) Determine the value of $\mathrm{\beta },$ ${\mathrm{I}}_{\mathrm{E}}$ and $\mathrm{\alpha }.$ $\left(\mathrm{i}\mathrm{i}\right)$ A change of $27 \mathrm{\mu }\mathrm{A}$ in the base current produces a change of $0.6 \mathrm{m}\mathrm{A}$ in the collector current. Find ${\beta }_{ac}$.

A transistor is used in common emitter mode in an amplifier circuit. When a signal of $30 \mathrm{m}\mathrm{V}$ is added to the base‐emitter voltage, the base current changes by $30 \mathrm{\mu }\mathrm{A}$ and collector current by $3 \mathrm{m}\mathrm{A}.$ The load resistance is $5 \mathrm{k}\mathrm{\Omega }$. Calculate (i) the current gain $\mathrm{\beta }$ (ii) the input resistance $R_{BE}$ (iii) transconductance and (iv) voltage gain.

In the circuit shown in figure, the base current $I_B=5.0 \mathrm{\mu }\mathrm{A}$, base resistor $R_B=1.0 \mathrm{M}\mathrm{\Omega }$, collector resistor $R_C=1.1 \mathrm{k\Omega }$, the collector current $I_C=5.0 \mathrm{m}\mathrm{A}$ and the $\mathrm{d}.\mathrm{c}$. voltage in the collector circuit ${\mathrm{V}}_{\mathrm{C}\mathrm{C}}=6.0 \mathrm{V}$. (i) Can this circuit be used as an amplifier? (ii) What happens if the resistance $R_C$ is $400 \mathrm{\Omega }$ and $I_B,$ $I_C$ and $R_B$ remains same as above?

As shown in figure, an amplifier of no-load gain $400$ and input resistance $100 \mathrm{\Omega }$ is connected to external signal via a series resistance of $300 \mathrm{\Omega }$. What is the apparent voltage gain?